Tutorial Completo Ansys

TUTORIAL ANSYS

|

TÓPICOS

_______________________________________________________________________________________ Introduction

Starting up ANSYS

ANSYS Interface

FEM Convergence Testing

ANSYS Saving an Restoring

jobs

ANSYS Files

Printing and Plotting ANSYS

Results to a File

Finite Element Method Using

Pro-ENGINEER and ANSYS

Two Dimensional Truss

Space Frame Example

Plane Stress Bracket

Modeling Tools in ANSYS

Solid Model Creation

Effect of Self Weight on a

Cantilever Beam

Application of Distributed

Loads

Non Linear Analysis of a

Cantilever Beam

Graphical Solution Tracking

Buckling

Non Linear Materials

Modal Analysis of a

Cantilever Beam

Harmonic Analysis of a

Cantilever Beam

Transient Analysis of a

Cantilever Beam

Simple Conduction example

Thermal – Mixed Boundary

Example

Transient Thermal

Conduction example

Modelling Using

Axisymmetry

Application of Joints and

Springs in ANSYS

Design Optimization

Substructuring

Coupled Structural –

Thermal Analysis

Using P-Elements

Melting Using Elements

Death

Contact Elements

ANSYS Parametric Design

Language (APDL)

Viewing X-Sectional Results

Advanced X-Sectional

Results

Data Plotting

Changing Graphical

Properties

ANSYS Command File

Creation and Execution

ANSYS Command File

Programming Features

CLT – Two Dimensional

Truss

CLT – Bicycle Space Frame

CLT – Plane Stress Bracket

CLT – Solid Modeling

CLT – Effect of Self Weight

CLT – Non Linear Analysis

CLT – Buckling

CLT – Dynamic Analysis –

Modal


Harmonic


Transient

CLT – Thermal Examples –

Transient Heat Conduction

CLT – Modelling Using

Axisymmetry

CLT – Springs and Joints

CLT – Design Optimization

CLT – Substructuring

CLT – Coupled Structural –

Thermal Analysis

CLT – Using P – Elements

CLT – Melting Using

Elements Death

CLT - Contact Elements

CLT – ANSYS Parametric

Design Language

CLT – Viewing Cross

Sectional Results

CLT – Advanced X-Sectional

Results

CLT – Data Plotting

Radiation Example

ANSYS Utilities

Basic Tutorials

Intermediate Tutorials

Advanced Tutorials

PostProc Tutorials

Command Line Files

Introduction ANSYS is a general purpose finite element modeling package for numerically solving a wide variety of mechanical problems. These problems include: static/dynamic structural analysis (both linear and non-linear), heat transfer and fluid problems, as well as acoustic and electro-magnetic problems.

In general, a finite element solution may be broken into the following three stages. This is a general guideline that can be used for setting up any finite element analysis.

1. Preprocessing: defining the problem; the major steps in preprocessing are given below: Define keypoints/lines/areas/volumes Define element type and material/geometric properties Mesh lines/areas/volumes as required

The amount of detail required will depend on the dimensionality of the analysis (i.e. 1D, 2D, axi-symmetric, 3D).

2. Solution: assigning loads, constraints and solving; here we specify the loads (point or pressure), contraints (translational and rotational) and finally solve the resulting set of equations.

3. Postprocessing: further processing and viewing of the results; in this stage one may wish to see: Lists of nodal displacements Element forces and moments Deflection plots Stress contour diagrams

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/GS/Intro/Print.html

Copyright © 2001 University of Alberta

Starting up ANSYS

Starting up ANSYS

Large File Sizes

ANSYS can create rather large files when running and saving; be sure that your local drive has space for it.

Getting the Program Started

In the Mec E 3-3 lab, there are two ways that you can start up ANSYS:

1. Windows NT application 2. Unix X-Windows application

Windows NT Start Up

Starting up ANSYS in Windows NT is simple:

Start Menu Programs ANSYS 5.7 Run Interactive Now

Unix X-Windows Start Up

Starting the Unix version of ANSYS involves a few more steps:

in the task bar at the bottom of the screen, you should see something labeled X-Win32. If you don't see this minimized program, you can may want to reboot the computer, as it automatically starts this application when booting. right click on this menu and selection Sessions and then select Mece. you will now be prompted to login to GPU... do this. once the Xwindows emulator has started, you will see an icon at the bottom of the screen that looks like a paper and pencil; don't select this icon, but rather, click on the up arrow above it and select Terminal a terminal command window will now start up in that window, type xansys57 at the UNIX prompt and a small launcher menu will appear.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/GS/Starting/Print.html


select the Run Interactive Now menu item.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/GS/Starting/Print.html


ANSYS 7.0 Environment The ANSYS Environment for ANSYS 7.0 contains 2 windows: the Main Window and an Output Window. Note that this is somewhat different from the previous version of ANSYS which made use of 6 different windows.

1. Main Window

Within the Main Window are 5 divisions:

a. Utility Menu

The Utility Menu contains functions that are available throughout the ANSYS session, such as file controls, selections, graphic controls and parameters.

b. Input Lindow

The Input Line shows program prompt messages and allows you to type in commands directly.

c. Toolbar

The Toolbar contains push buttons that execute commonly used ANSYS commands. More push buttons can be added if desired.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/GS/Environ/Print.html


d. Main Menu

The Main Menu contains the primary ANSYS functions, organized by preprocessor, solution, general postprocessor, design optimizer. It is from this menu that the vast majority of modelling commands are issued. This is where you will note the greatest change between previous versions of ANSYS and version 7.0. However, while the versions appear different, the menu structure has not changed.

e. Graphics Window

The Graphic Window is where graphics are shown and graphical picking can be made. It is here where you will graphically view the model in its various stages of construction and the ensuing results from the analysis.

2. Output Window

The Output Window shows text output from the program, such as listing of data etc. It is usually positioned behind the main window and can de put to the front if necessary.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/GS/Environ/Print.html


ANSYS Interface Graphical Interface vs. Command File Coding

There are two methods to use ANSYS. The first is by means of the graphical user interface or GUI. This method follows the conventions of popular Windows and X-Windows based programs.

The second is by means of command files. The command file approach has a steeper learning curve for many, but it has the advantage that an entire analysis can be described in a small text file, typically in less than 50 lines of commands. This approach enables easy model modifications and minimal file space requirements.

The tutorials in this website are designed to teach both the GUI and the command file approach, however, many of you will find the command file simple and more efficient to use once you have invested a small amount of time into learning the code.

For information and details on the full ANSYS command language, consult:

Help > Table of Contents > Commands Manual.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/GS/Interface/Print.html


FEM Convergence Testing

Introduction

A fundamental premise of using the finite element procedure is that the body is sub-divided up into small discrete regions known as finite elements. These elements defined by nodes and interpolation functions. Governing equations are written for each element and these elements are assembled into a global matrix. Loads and constraints are applied and the solution is then determined.

The Problem

The question that always arises is: How small do I need to make the elements before I can trust the solution?

What to do about it...

In general there are no real firm answers on this. It will be necessary to conduct convergence tests! By this we mean that you begin with a mesh discretization and then observe and record the solution. Now repeat the problem with a finer mesh (i.e. more elements) and then compare the results with the previous test. If the results are nearly similar, then the first mesh is probably good enough for that particular geometry, loading and constraints. If the results differ by a large amount however, it will be necessary to try a finer mesh yet.

The Consequences

Finer meshes come with a cost however: more calculational time and large memory requirements (both disk and RAM)! It is desired to find the minimum number of elements that give you a converged solution.

Beam Models

For beam models, we actually only need to define a single element per line unless we are applying a distributed load on a given frame member. When point loads are used, specifying more that one element per line will not change the solution, it will only slow the calculations down. For simple models it is of no concern, but for a larger model, it is desired to minimize the number of elements, and thus calculation time and still obtain the desired accuracy.

General Models

In general however, it is necessary to conduct convergence tests on your finite element model to confirm that a fine enough element discretization has been used. In a solid mechanics problem, this would be done by creating several models with different mesh sizes and comparing the resulting deflections and stresses, for example. In general, the stresses will converge more slowly than the displacement, so it is not sufficient to examine the displacement convergence.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/UT/Converge/Print.html


ANSYS: Saving and Restoring Jobs

Saving Your Job

It is good practice to save your model at various points during its creation. Very often you will get to a point in the modeling where things have gone well and you like to save it at the point. In that way, if you make some mistakes later on, you will at least be able to come back to this point.

To save your model, select Utility Menu Bar -> File -> Save As Jobname.db. Your model will be saved in a file called jobname.db, where jobname is the name that you specified in the Launcher when you first started ANSYS.

It is a good idea to save your job at different times throughout the building and analysis of the model to backup your work incase of a system crash or other unforseen problems.

Recalling or Resuming a Previously Saved Job

Frequently you want to start up ANSYS and recall and continue a previous job. There are two methods to do this:

1. Using the Launcher... In the ANSYS Launcher, select Interactive... and specify the previously defined jobname. Then when you get ANSYS started, select Utility Menu -> File -> Resume Jobname.db . This will restore as much of your database (geometry, loads, solution, etc) that you previously saved.

2. Or, start ANSYS and select Utitily Menu -> File -> Resume from... and select your job from the list that appears.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/UT/Saving/Print.html


ANSYS Files

Introduction A large number of files are created when you run ANSYS. If you started ANSYS without specifying a jobname, the name of all the files created will be FILE.* where the * represents various extensions described below. If you specified a jobname, say Frame, then the created files will all have the file prefix, Frame again with various extensions:

frame.db Database file (binary). This file stores the geometry, boundary conditions and any solutions.

frame.dbb Backup of the database file (binary).

frame.err Error file (text). Listing of all error and warning messages.

frame.out Output of all ANSYS operations (text). This is what normally scrolls in the output window during an ANSYS session.

frame.log Logfile or listing of ANSYS commands (text). Listing of all equivalent ANSYS command line commands used during the current session.

etc... Depending on the operations carried out, other files may have been written. These files may contain results, etc.

What to save? When you want to clean up your directory, or move things from the /scratch directory, what files do you need to save?

If you will always be using the GUI, then you only require the .db file. This file stores the geometry, boundary conditions and any solutions. Once the ANSYS has started, and the jobname has been specified, you need only activate the resume command to proceed from where you last left off (see Saving and Restoring Jobs). If you plan on using ANSYS command files, then you need only store your command file and/or the log file. This file contains a complete listing of the ANSYS commands used to get you model to its current point. That file may be rerun as is, or edited and rerun as desired (Command File Creation and Execution).

If you plan to use the command mode of operation, starting with an existing log file, rename it first so that it does not get over-written or added to, from another ANSYS run.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/UT/Files/Print.html


Printing and Plotting ANSYS Results to a File

Printing Text Results to a File ANSYS produces lists and tables of many types of results that are normally displayed on the screen. However, it is often desired to save the results to a file to be later analyzed or included in a report.

1. Stresses: instead of using 'Plot Results' to plot the stresses, choose 'List Results'. Select 'Elem Table Data', and choose what you want to list from the menu. You can pick multiple items. When the list appears on the screen in its own window, Select 'File'/'Save As...' and give a file name to store the results.

2. Any other solutions can be done in the same way. For example select 'Nodal Solution' from the 'List Results' menu, to get displacements.

3. Preprocessing and Solution data can be listed and saved from the 'List' menu in the 'Utility Menu bar'. Save the resulting list in the same way described above.

Plotting of Figures There are two major routes to get hardcopies from ANSYS. The first is a quick a raster-based screen dump, while the second is a scalable vector plot.

1.0 Quick Image Save

When you want to quickly save an image of the entire screen or the current 'Graphics window', select:

'Utility menu bar'/'PlotCtrls'/'Hard Copy ...'. In the window that appears, you will normally want to select 'Graphics window', 'Monochrome', 'Reverse Video', 'Landscape' and 'Save to:'. Then enter the file name of your choice. Press 'OK'

This raster image file may now be printed on a PostScript printer or included in a document.

2.0 Better Quality Plots

The second method of saving a plot is much more flexible, but takes a lot more work to set up as you'll see...

Redirection

Normally all ANSYS plots are directed to the plot window on the screen. To save some plots to a file, to be later printed or included in a document or what have you, you must first 'redirect' the plots to a file by issuing:

'Utility menu bar'/'PlotCtrls'/'Redirect Plots'/'To File...'.

Type in a filename (e.g.: frame.pic) in the 'Selection' Window.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/UT/Printing/Print.html


Now issue whatever plot commands you want within ANSYS, remembering that the plots will not be displayed to the screen, but rather they will be written to the selected file. You can put as many plots as you want into the plot file. When you are finished plotting what you want to the file, redirect plots back to the screen using:

'Utility menu bar'/'PlotCtrls'/'Redirect Plots'/'To Screen'.

Display and Conversion

The plot file that has been saved is stored in a proprietary file format that must be converted into a more common graphic file format like PostScript, or HPGL for example. This is performed by running a separate program called display. To do this, you have a couple of options:

1. select display from the ANSYS launcher menu (if you started ANSYS that way) 2. shut down ANSYS or open up a new terminal window and then type display at the Unix prompt.

Either way, a large graphics window will appear. Decrease the size of this window, because it most likely covers the window in which you will enter the display plotting commands. Load your plot file with the following command:

file,frame,pic

if your plot file is 'plots.pic'. Note that although the file is 'plots.pic' (with a period), Display wants 'plots,pic'(with a comma). You can display your plots to the graphics window by issuing the command like

plot,n

where n is plot number. If you plotted 5 images to this file in ANSYS, then n could be any number from 1 to 5.

Now that the plots have been read in, they may be saved to printer files of various formats:

1. Colour PostScript: To save the images to a colour postscript file, enter the following commands in display:

pscr,color,2 /show,pscr plot,n

where n is the plot number, as above. You can plot as many images as you want to postscript files in this manner. For subsequent plots, you only require the plot,n command as the other options have now been set. Each image is plotted to a postscript file such as pscrxx.grph, where xx is a number, starting at 00.

Note: when you import a postscript file into a word processor, the postscript image will appear as blank box. The printer information is still present, but it can only be viewed when it's printed out to a postscript printer.

Printing it out: Now that you've got your color postscript file, what are you going to do with it? Take a look here for instructions on colour postscript printing at a couple of sites on campus where you can have your beautiful stress plot plotted to paper, overheads or even posters!

2. Black & White PostScript: The above mentioned colour postscript files can get very large in size and



may not even print out on the postscript printer in the lab because it takes so long to transfer the files to the printer and process them. A way around this is to print them out in a black and white postscript format instead of colour; besides the colour specifications don't do any good for the black and white lab printer anyways. To do this, you set the postscript color option to '3', i.e. and then issue the other commands as before

pscr,color,3 /show,pscr plot,n

Note: when you import a postscript file into a word processor, the postscript image will appear as blank box. The printer information is still present, but it can only be viewed when it's printed out to a postscript printer.

3. HPGL: The third commonly used printer format is HPGL, which stands for Hewlett Packard Graphics Language. This is a compact vector format that has the advantage that when you import a file of this type into a word processor, you can actually see the image in the word processor! To use the HPGL format, issue the following commands:

/show,hpgl plot,n

Final Steps

It is wise to rename these plot files as soon as you leave display, for display will overwrite the files the next time it is run. You may want to rename the postscript files with an '.eps' extension to indicate that they are encapsulated postscript images. In a similar way, the HPGL printer files could be given an '.hpgl' extension. This renaming is done at the Unix commmand line (the 'mv' command).

A list of all available display commands and their options may be obtained by typing:

help

When complete, exit display by entering

finish



Finite Element Method using Pro/ENGINEER and ANSYS Notes by R.W. Toogood

The transfer of a model from Pro/ENGINEER to ANSYS will be demonstrated here for a simple solid model. Model idealizations such as shells and beams will not be treated. Also, many modeling options for constraints, loads, mesh control, analysis types will not be covered. These are fairly easy to figure out once you know the general procedures presented here.

Step 1. Make the part

Use Pro/E to make the part. Things to note are:

be aware of your model units note the orientation of the model (default coordinate system in ANSYS will be the same as in Pro/E) IMPORTANT: remove all unnecessary and/or cosmetic features like rounds, chamfers, holes, etc., by suppressing them in Pro/E. Too much small geometry will cause the mesh generator to create a very fine mesh with many elements which will greatly increase your solver time. Of course, if the feature is critical to your design, you will want to leave it. You must compromise between accuracy and available CPU resources.

The figure above shows the original model for this demonstration. This is a model of a short cantilevered bracket that bolts to the wall via the thick plate on the left end. Model units are inches. A load is applied at the hole in the right end. Some cosmetic features are located on the top surface and the two sides. Several edges are rounded. For this model, the interest is in the stress distribution around the vertical slot. So, the plate and the loading hole are removed, as are the cosmetic features and rounds resulting in the "de-featured" geometry shown below. The model will be constrained on the left face and a uniform load will be applied to the right face.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AU/ProE/ProE.html


Step 2. Create the FEM model

In the pull-down menu at the top of the Pro/E window, select

Applications > Mechanica

An information window opens up to remind you about the units you are using. Press Continue

In the MECHANICA menu at the right, check the box beside FEM Mode and select the command Structure.

A new toolbar appears on the right of the screen that contains icons for creating all the common modeling entities (constraints, loads, idealizations). All these commands are also available using the command windows that will open on the right side of the screen or in dialog windows that will open when appropriate.

Notice that a small green coordinate system WCS has appeared. This is how you will specify the directions of constraints and forces. Other coordinate systems (eg cylindrical) can be created as required and used for the same purpose.

The MEC STRUCT menu appears on the right. Basically, to define the model we proceed down this menu in a top-down manner. Model is already selected for you which opens the STRC MODEL menu. This is where we specify modeling information. We proceed in a top-down manner. The Features command allows you to create additional simulation features like datum points, curves, surface regions, and so on. Idealizations lets you create special modeling entities like shells and beams. The Current CSYS command lets you create or select an alternate coordinate system for specifying directions of constraints and loads.

Defining Constraints

For our simple model, all we need are constraints, loads, and a specified material. Select

Constraints > New

We can specify constraints on four entity types (basically points, edges, and surfaces). Constraints are organized into constraint sets. Each constraint set has a unique name (default of the first one is ConstraintSet1) and can contain any number of individual constraints of different types. Each individual constraint also has a unique name (default of the first one is Constraint1). In the final computed model, only one set can be included, but this can contain numerous individual constraints.



Select Surface. We are going to fully constrain the left face of the cantilever. A dialog window opens as shown above. Here you can give a name to the constraint and identify which constraint set it belongs to. Since we elected to create a surface constraint, we now select the surface we want constrained (push the Surface selection button in the window and then click on the desired surface of the model). The constraints to be applied are selected using the buttons at the bottom of the window. In general we specify constraints on translation and rotation for any mesh node that will appear on the selected entity. For each direction X, Y, and Z, we can select one of the four buttons (Free, Fixed, Prescribed, and Function of Coordinates). For our solid model, the rotation constraints are irrelevant (since nodes of solid elements do not have this degree of freedom anyway). For beams and shells, rotational constraints are active if specified.

For our model, leave all the translation constraints as FIXED, and select the OK button. You should now see some orange symbols on the left face of the model, along with some text labels that summarize the constraint settings.

Defining Loads

In the STRC MODEL menu select

Loads > New > Surface



The FORCE/MOMENT window opens as shown above. Loads are also organized into named load sets. A load set can contain any number of individual loads of different types. A FEM model can contain any number of different load sets. For example, in the analysis of a pressurized tank on a support system with a number of nozzle connections to other pipes, one load set might contain only the internal pressure, another might contain the support forces, another a temperature load, and more might contain the forces applied at each nozzle location. These can be solved at the same time, and the principle of superposition used to combine them in numerous ways.

Create a load called "end_load" in the default load set (LoadSet1)

Click on the Surfaces button, then select the right face of the model and middle click to return to this dialog. Leave the defaults for the load distribution. Enter the force components at the bottom. Note these are relative to the WCS. Then select OK. The load should be displayed symbolically as shown in the figure below.

Note that constraint and load sets appear in the model tree. You can select and edit these in the usual way using the right mouse button.



Assigning Materials

Our last job to define the model is to specify the part material. In the STRC MODEL menu, select

Materials > Whole Part

In the library dialog window, select a material and move it to the right pane using the triple arrow button in the center of the window. In an assembly, you could now assign this material to individual parts. If you select the Edit button, you will see the properties of the chosen material.

At this point, our model has the necessary information for solution (constraints, loads, material).

Step 3. Define the analysis

Select

Analyses > New

Specify a name for the analysis, like "ansystest". Select the type (Structural or Modal). Enter a short description. Now select the Add buttons beside the Constraints and Loads panes to add ConstraintSet1 and LoadSet1 to the analysis. Now select OK.

Step 4. Creating the mesh

We are going to use defaults for all operations here. The MEC STRUCT window, select

Mesh > Create > Solid > Start

Accept the default for the global minimum. The mesh is created and another dialog window opens (Element Quality Checks).



This indicates some aspects of mesh quality that may be specified and then, by selecting the Check button at the bottom, evaluated for the model. The results are indicated in columns on the right. If the mesh does not pass these quality checks, you may want to go back to specify mesh controls (discussed below). Select Close. Here is an image of the default mesh, shown in wire frame.

Improving the Mesh

In the mesh command, you can select the Controls option. This will allow you to select points, edges, and surfaces where you want to specify mesh geometry such as hard points, maximum mesh size, and so on. Beware that excessively tight mesh controls can result in meshes with many elements.



For example, setting a maximum mesh size along the curved ends of the slot results in the following mesh. Notice the better representation of the curved edges than in the previous figure. This is at the expense of more than double the number of elements. Note that mesh controls are also added to the model tree.

Step 5. Creating the Output file

All necessary aspects of the model are now created (constraints, loads, materials, mesh). In the MEC STRUCT menu, select

Run



This opens the Run FEM Analysis dialog window shown here. In the Solver pull-down list at the top, select ANSYS. In the Analysis list, select Structural. You pick either Linear or Parabolic elements. The analysis we defined (containing constraints, loads, mesh, and material) is listed. Select the Output to File radio button at the bottom and specify the output file name (default is the analysis name with extension .ans). Select OK and read the message window.

We are now finished with Pro/E. Go to the top pull-down menus and select

Applications > Standard

Save the model file and leave the program.

Copy the .ans file from your Pro/E working directory to the directory you will use for running ANSYS.

Step 6. Importing into ANSYS

Launch ANSYS Interactive and select

File > Read Input From...

Select the .ans file you created previously. This will read in the entire model. You can display the model using (in the pull down menus) Plot > Elements.

Step 7. Running the ANSYS solver

In the ANSYS Main Menu on the left, select

Solution > Solve > Current LS > OK



After a few seconds, you will be informed that the solution is complete.

Step 8. Viewing the results

There are myriad possibilities for viewing FEM results. A common one is the following:

General Postproc > Plot Results > Contour Plot > Nodal Solu

Pick the Von Mises stress values, and select Apply. You should now have a color fringe plot of the Von Mises stress displayed on the model.

Updated: 8 November 2002 using Pro/ENGINEER 2001 RWT Please report errors or omissions to Roger Toogood




Introduction This tutorial was created using ANSYS 7.0 to solve a simple 2D Truss problem. This is the first of four introductory ANSYS tutorials.

Problem Description

Determine the nodal deflections, reaction forces, and stress for the truss system shown below (E = 200GPa, A = 3250mm2).

(Modified from Chandrupatla & Belegunda, Introduction to Finite Elements in Engineering, p.123)

Preprocessing: Defining the Problem 1. Give the Simplified Version a Title (such as 'Bridge Truss Tutorial').

In the Utility menu bar select File > Change Title:

The following window will appear:

Enter the title and click 'OK'. This title will appear in the bottom left corner of the 'Graphics' Window once you begin. Note: to get the title to appear immediately, select Utility Menu > Plot > Replot

2. Enter Keypoints

The overall geometry is defined in ANSYS using keypoints which specify various principal coordinates

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/BT/Truss/Truss.html


to define the body. For this example, these keypoints are the ends of each truss.

We are going to define 7 keypoints for the simplified structure as given in the following table

(these keypoints are depicted by numbers in the above figure)

From the 'ANSYS Main Menu' select: Preprocessor > Modeling > Create > Keypoints > In Active CS

The following window will then appear:

To define the first keypoint which has the coordinates x = 0 and y = 0:

keypointcoordinatex y

1 0 0 2 1800 31183 3600 04 5400 31185 7200 06 9000 31187 10800 0



Enter keypoint number 1 in the appropriate box, and enter the x,y coordinates: 0, 0 in their appropriate boxes (as shown above). Click 'Apply' to accept what you have typed.

Enter the remaining keypoints using the same method.

Note: When entering the final data point, click on 'OK' to indicate that you are finished entering keypoints. If you first press 'Apply' and then 'OK' for the final keypoint, you will have defined it twice! If you did press 'Apply' for the final point, simply press 'Cancel' to close this dialog box.

Units Note the units of measure (ie mm) were not specified. It is the responsibility of the user to ensure that a consistent set of units are used for the problem; thus making any conversions where necessary.

Correcting Mistakes When defining keypoints, lines, areas, volumes, elements, constraints and loads you are bound to make mistakes. Fortunately these are easily corrected so that you don't need to begin from scratch every time an error is made! Every 'Create' menu for generating these various entities also has a corresponding 'Delete' menu for fixing things up.

3. Form Lines

The keypoints must now be connected

We will use the mouse to select the keypoints to form the lines.

In the main menu select: Preprocessor > Modeling > Create > Lines > Lines > In Active Coord. The following window will then appear:

Use the mouse to pick keypoint #1 (i.e. click on it). It will now be marked by a small yellow box.



Now move the mouse toward keypoint #2. A line will now show on the screen joining these two points. Left click and a permanent line will appear.

Connect the remaining keypoints using the same method.

When you're done, click on 'OK' in the 'Lines in Active Coord' window, minimize the 'Lines' menu and the 'Create' menu. Your ANSYS Graphics window should look similar to the following figure.

Disappearing Lines Please note that any lines you have created may 'disappear' throughout your analysis. However, they have most likely NOT been deleted. If this occurs at any time from the Utility Menu select:

Plot > Lines

4. Define the Type of Element

It is now necessary to create elements. This is called 'meshing'. ANSYS first needs to know what kind of elements to use for our problem:

From the Preprocessor Menu, select: Element Type > Add/Edit/Delete. The following window will then appear:



Click on the 'Add...' button. The following window will appear:

For this example, we will use the 2D spar element as selected in the above figure. Select the element shown and click 'OK'. You should see 'Type 1 LINK1' in the 'Element Types' window.

Click on 'Close' in the 'Element Types' dialog box.

5. Define Geometric Properties

We now need to specify geometric properties for our elements: In the Preprocessor menu, select Real Constants > Add/Edit/Delete



Click Add... and select 'Type 1 LINK1' (actually it is already selected). Click on 'OK'. The following window will appear:

As shown in the window above, enter the cross-sectional area (3250mm): Click on 'OK'. 'Set 1' now appears in the dialog box. Click on 'Close' in the 'Real Constants' window.

6. Element Material Properties

You then need to specify material properties: In the 'Preprocessor' menu select Material Props > Material Models



Double click on Structural > Linear > Elastic > Isotropic

We are going to give the properties of Steel. Enter the following field:

Set these properties and click on 'OK'. Note: You may obtain the note 'PRXY will be set to 0.0'. This is poisson's ratio and is not required for this element type. Click 'OK' on the window to continue. Close the "Define Material Model Behavior" by clicking on the 'X' box in the upper right hand corner.

7. Mesh Size

The last step before meshing is to tell ANSYS what size the elements should be. There are a variety of ways to do this but we will just deal with one method for now.

In the Preprocessor menu select Meshing > Size Cntrls > ManualSize > Lines > All Lines

EX 200000



In the size 'NDIV' field, enter the desired number of divisions per line. For this example we want only 1 division per line, therefore, enter '1' and then click 'OK'. Note that we have not yet meshed the geometry, we have simply defined the element sizes.

8. Mesh

Now the frame can be meshed. In the 'Preprocessor' menu select Meshing > Mesh > Lines and click 'Pick All' in the 'Mesh Lines' Window

Your model should now appear as shown in the following window

Plot Numbering To show the line numbers, keypoint numbers, node numbers...



From the Utility Menu (top of screen) select PlotCtrls > Numbering...

Fill in the Window as shown below and click 'OK'

Now you can turn numbering on or off at your discretion

Saving Your Work

Save the model at this time, so if you make some mistakes later on, you will at least be able to come back to this point. To do this, on the Utility Menu select File > Save as.... Select the name and location where you want to save your file.

It is a good idea to save your job at different times throughout the building and analysis of the model to backup your work in case of a system crash or what have you.

Solution Phase: Assigning Loads and Solving You have now defined your model. It is now time to apply the load(s) and constraint(s) and solve the the resulting system of equations.

Open up the 'Solution' menu (from the same 'ANSYS Main Menu').

1. Define Analysis Type

First you must tell ANSYS how you want it to solve this problem:

From the Solution Menu, select Analysis Type > New Analysis.



Ensure that 'Static' is selected; i.e. you are going to do a static analysis on the truss as opposed to a dynamic analysis, for example.

Click 'OK'.

2. Apply Constraints

It is necessary to apply constraints to the model otherwise the model is not tied down or grounded and a singular solution will result. In mechanical structures, these constraints will typically be fixed, pinned and roller-type connections. As shown above, the left end of the truss bridge is pinned while the right end has a roller connection.

In the Solution menu, select Define Loads > Apply > Structural > Displacement > On Keypoints

Select the left end of the bridge (Keypoint 1) by clicking on it in the Graphics Window and click on 'OK' in the 'Apply U,ROT on KPs' window.



This location is fixed which means that all translational and rotational degrees of freedom (DOFs) are constrained. Therefore, select 'All DOF' by clicking on it and enter '0' in the Value field and click 'OK'.

You will see some blue triangles in the graphics window indicating the displacement contraints.

Using the same method, apply the roller connection to the right end (UY constrained). Note that more than one DOF constraint can be selected at a time in the "Apply U,ROT on KPs" window. Therefore, you may need to 'deselect' the 'All DOF' option to select just the 'UY' option.

3. Apply Loads

As shown in the diagram, there are four downward loads of 280kN, 210kN, 280kN, and 360kN at keypoints 1, 3, 5, and 7 respectively.

Select Define Loads > Apply > Structural > Force/Moment > on Keypoints.

Select the first Keypoint (left end of the truss) and click 'OK' in the 'Apply F/M on KPs' window.

Select FY in the 'Direction of force/mom'. This indicate that we will be applying the load in the 'y' direction

Enter a value of -280000 in the 'Force/moment value' box and click 'OK'. Note that we are using units of N here, this is consistent with the previous values input.

The force will appear in the graphics window as a red arrow.



Apply the remaining loads in the same manner.

The applied loads and constraints should now appear as shown below.

4. Solving the System

We now tell ANSYS to find the solution:

In the 'Solution' menu select Solve > Current LS. This indicates that we desire the solution under the current Load Step (LS).

The above windows will appear. Ensure that your solution options are the same as shown above and click 'OK'.

Once the solution is done the following window will pop up. Click 'Close' and close the /STATUS



Command Window..

Postprocessing: Viewing the Results 1. Hand Calculations

We will first calculate the forces and stress in element 1 (as labeled in the problem description).

2. Results Using ANSYS

Reaction Forces

A list of the resulting reaction forces can be obtained for this element

from the Main Menu select General Postproc > List Results > Reaction Solu.



Select 'All struc forc F' as shown above and click 'OK'

These values agree with the reaction forces claculated by hand above.

Deformation

In the General Postproc menu, select Plot Results > Deformed Shape. The following window will appear.

Select 'Def + undef edge' and click 'OK' to view both the deformed and the undeformed object.



Observe the value of the maximum deflection in the upper left hand corner (DMX=7.409). One should also observe that the constrained degrees of freedom appear to have a deflection of 0 (as expected!)

Deflection

For a more detailed version of the deflection of the beam,

From the 'General Postproc' menu select Plot results > Contour Plot > Nodal Solution. The following window will appear.



Select 'DOF solution' and 'USUM' as shown in the above window. Leave the other selections as the default values. Click 'OK'.

Looking at the scale, you may want to use more useful intervals. From the Utility Menu select Plot Controls > Style > Contours > Uniform Contours...

Fill in the following window as shown and click 'OK'.



You should obtain the following.

The deflection can also be obtained as a list as shown below. General Postproc > List Results > Nodal Solution select 'DOF Solution' and 'ALL DOFs' from the lists in the 'List Nodal Solution' window and click 'OK'. This means that we want to see a listing of all degrees of freedom from the solution.



Are these results what you expected? Note that all the degrees of freedom were constrained to zero at node 1, while UY was constrained to zero at node 7.

If you wanted to save these results to a file, select 'File' within the results window (at the upper left-hand corner of this list window) and select 'Save as'.

Axial Stress

For line elements (ie links, beams, spars, and pipes) you will often need to use the Element Table to gain access to derived data (ie stresses, strains). For this example we should obtain axial stress to compare with the hand calculations. The Element Table is different for each element, therefore, we need to look at the help file for LINK1 (Type help link1 into the Input Line). From Table 1.2 in the Help file, we can see that SAXL can be obtained through the ETABLE, using the item 'LS,1'

From the General Postprocessor menu select Element Table > Define Table

Click on 'Add...'

As shown above, enter 'SAXL' in the 'Lab' box. This specifies the name of the item you are defining. Next, in the 'Item,Comp' boxes, select 'By sequence number' and 'LS,'. Then enter 1 after LS, in the selection box

Click on 'OK' and close the 'Element Table Data' window.



Plot the Stresses by selecting Element Table > Plot Elem Table

The following window will appear. Ensure that 'SAXL' is selected and click 'OK'

Because you changed the contour intervals for the Displacement plot to "User Specified" - you need to switch this back to "Auto calculated" to obtain new values for VMIN/VMAX.

Utility Menu > PlotCtrls > Style > Contours > Uniform Contours ...

Again, you may wish to select more appropriate intervals for the contour plot

List the Stresses From the 'Element Table' menu, select 'List Elem Table' From the 'List Element Table Data' window which appears ensure 'SAXL' is highlighted Click 'OK'



Note that the axial stress in Element 1 is 82.9MPa as predicted analytically.

Command File Mode of Solution The above example was solved using the Graphical User Interface (or GUI). This problem has also been solved using the ANSYS command language interface that you may want to browse. Open the file and save it to your computer. Now go to 'File > Read input from...' and select the file.

Quitting ANSYS To quit ANSYS, select 'QUIT' from the ANSYS Toolbar or select Utility Menu/File/Exit.... In the dialog box that appears, click on 'Save Everything' (assuming that you want to) and then click on 'OK'.



Space Frame Example

Introduction This tutorial was created using ANSYS 7.0 to solve a simple 3D space frame problem.

Problem Description

The problem to be solved in this example is the analysis of a bicycle frame. The problem to be modeled in this example is a simple bicycle frame shown in the following figure. The frame is to be built of hollow aluminum tubing having an outside diameter of 25mm and a wall thickness of 2mm.

Verification The first step is to simplify the problem. Whenever you are trying out a new analysis type, you need something (ie analytical solution or experimental data) to compare the results to. This way you can be sure that you've gotten the correct analysis type, units, scale factors, etc.

The simplified version that will be used for this problem is that of a cantilever beam shown in the following figure:

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/BT/Bike/Bike.html


Preprocessing: Defining the Problem

1. Give the Simplified Version a Title (such as 'Verification Model').

Utility Menu > File > Change Title

2. Enter Keypoints

For this simple example, these keypoints are the ends of the beam.

We are going to define 2 keypoints for the simplified structure as given in the following table

From the 'ANSYS Main Menu' select: Preprocessor > Modeling > Create > Keypoints > In Active CS

3. Form Lines

The two keypoints must now be connected to form a bar using a straight line.

Select: Preprocessor > Modeling> Create > Lines > Lines > Straight Line.

Pick keypoint #1 (i.e. click on it). It will now be marked by a small yellow box.

Now pick keypoint #2. A permanent line will appear.

When you're done, click on 'OK' in the 'Create Straight Line' window.


It is now necessary to create elements on this line.

keypointcoordinatex y z

1 0 0 0 2 500 0 0



From the Preprocessor Menu, select: Element Type > Add/Edit/Delete.

Click on the 'Add...' button. The following window will appear:

For this example, we will use the 3D elastic straight pipe element as selected in the above figure. Select the element shown and click 'OK'. You should see 'Type 1 PIPE16' in the 'Element Types' window.

Click on the 'Options...' button in the 'Element Types' dialog box. The following window will appear:

Click and hold the K6 button (second from the bottom), and select 'Include Output' and click 'OK'. This gives us extra force and moment output.

Click on 'Close' in the 'Element Types' dialog box and close the 'Element Type' menu.


We now need to specify geometric properties for our elements:

In the Preprocessor menu, select Real Constants > Add/Edit/Delete



Click Add... and select 'Type 1 PIPE16' (actually it is already selected). Click on 'OK'.

Enter the following geometric properties:

Outside diameter OD: 25 Wall thickness TKWALL: 2

This defines an outside pipe diameter of 25mm and a wall thickness of 2mm.

Click on 'OK'.

'Set 1' now appears in the dialog box. Click on 'Close' in the 'Real Constants' window.


You then need to specify material properties: In the 'Preprocessor' menu select Material Props > Material Models...

Double click Structural > Linear > Elastic and select 'Isotropic' (double click on it)

Close the 'Define Material Model Behavior' Window.

We are going to give the properties of Aluminum. Enter the following field:

Set these properties and click on 'OK'.

7. Mesh Size In the Preprocessor menu select Meshing > Size Cntrls > ManualSize > Lines > All Lines

In the size 'SIZE' field, enter the desired element length. For this example we want an element length of 2cm, therefore, enter '20' (i.e 20mm) and then click 'OK'. Note that we have not yet meshed the geometry, we have simply defined the element sizes.

(Alternatively, we could enter the number of divisions we want in the line. For an element length of 2cm, we would enter 25 [ie 25 divisions]).

NOTE It is not necessary to mesh beam elements to obtain the correct solution. However, meshing is done in this case so that we can obtain results (ie stress, displacement) at intermediate positions on the beam.

8. Mesh

Now the frame can be meshed. In the 'Preprocessor' menu select Meshing > Mesh > Lines and click 'Pick All' in the 'Mesh Lines' Window

9. Saving Your Work

Utility Menu > File > Save as.... Select the name and location where you want to save your file.

EX 70000PRXY 0.33



Solution Phase: Assigning Loads and Solving


From the Solution Menu, select 'Analysis Type > New Analysis'.

Ensure that 'Static' is selected and click 'OK'.


In the Solution menu, select Define Loads > Apply > Structural > Displacement > On Keypoints

Select the left end of the rod (Keypoint 1) by clicking on it in the Graphics Window and click on 'OK' in the 'Apply U,ROT on KPs' window.

This location is fixed which means that all translational and rotational degrees of freedom (DOFs) are constrained. Therefore, select 'All DOF' by clicking on it and enter '0' in the Value field and click 'OK'.

3. Apply Loads

As shown in the diagram, there is a vertically downward load of 100N at the end of the bar

In the Structural menu, select Force/Moment > on Keypoints.

Select the second Keypoint (right end of bar) and click 'OK' in the 'Apply F/M' window.

Click on the 'Direction of force/mom' at the top and select FY.

Enter a value of -100 in the 'Force/moment value' box and click 'OK'.

The force will appear in the graphics window as a red arrow.





We now tell ANSYS to find the solution:

Solution > Solve > Current LS

Postprocessing: Viewing the Results

1. Hand Calculations

Now, since the purpose of this exercise was to verify the results - we need to calculate what we should find.

Deflection:

The maximum deflection occurs at the end of the rod and was found to be 6.2mm as shown above.

Stress:

The maximum stress occurs at the base of the rod and was found to be 64.9MPa as shown above (pure bending stress).

2. Results Using ANSYS



Deformation

from the Main Menu select General Postproc from the 'ANSYS Main Menu'. In this menu you will find a variety of options, the two which we will deal with now are 'Plot Results' and 'List Results'

Select Plot Results > Deformed Shape.

Select 'Def + undef edge' and click 'OK' to view both the deformed and the undeformed object.

Observe the value of the maximum deflection in the upper left hand corner (shown here surrounded by a blue border for emphasis). This is identical to that obtained via hand calculations.

Deflection

For a more detailed version of the deflection of the beam,

From the 'General Postproc' menu select Plot results > Contour Plot > Nodal Solution.

Select 'DOF solution' and 'USUM'. Leave the other selections as the default values. Click 'OK'.



You may want to have a more useful scale, which can be accomplished by going to the Utility Menu and selecting Plot Controls > Style > Contours > Uniform Contours

The deflection can also be obtained as a list as shown below. General Postproc > List Results > Nodal Solution ... select 'DOF Solution' and 'ALL DOFs' from the lists in the 'List Nodal Solution' window and click 'OK'. This means that we want to see a listing of all translational and rotational degrees of freedom from the solution. If we had only wanted to see the displacements for example, we would have chosen 'ALL Us' instead of 'ALL DOFs'.



Are these results what you expected? Again, the maximum deflection occurs at node 2, the right end of the rod. Also note that all the rotational and translational degrees of freedom were constrained to zero at node 1.

If you wanted to save these results to a file, use the mouse to go to the 'File' menu (at the upper left-hand corner of this list window) and select 'Save as'.

Stresses

For line elements (ie beams, spars, and pipes) you will need to use the Element Table to gain access to derived data (ie stresses, strains).

From the General Postprocessor menu select Element Table > Define Table...

Click on 'Add...'



As shown above, in the 'Item,Comp' boxes in the above window, select 'Stress' and 'von Mises SEQV'

Click on 'OK' and close the 'Element Table Data' window.

Plot the Stresses by selecting Plot Elem Table in the Element Table Menu

The following window will appear. Ensure that 'SEQV' is selected and click 'OK'

If you changed the contour intervals for the Displacement plot to "User Specified" you may need to switch this back to "Auto calculated" to obtain new values for VMIN/VMAX.

Utility Menu > PlotCtrls > Style > Contours > Uniform Contours ...



Again, select more appropriate intervals for the contour plot

List the Stresses From the 'Element Table' menu, select 'List Elem Table' From the 'List Element Table Data' window which appears ensure 'SEQV' is highlighted Click 'OK'

Note that a maximum stress of 64.914 MPa occurs at the fixed end of the beam as predicted analytically.

Bending Moment Diagrams

To further verify the simplified model, a bending moment diagram can be created. First, let's look at how ANSYS defines each element. Pipe 16 has 2 nodes; I and J, as shown in the following image.

To obtain the bending moment for this element, the Element Table must be used. The Element Table contains most of the data for the element including the bending moment data for each element at Node I and Node J. First, we need to obtain obtain the bending moment data.

General Postproc > Element Table > Define Table... . Click 'Add...'.



In the window, A. Enter IMoment as the 'User label for item' - this will give a name to the data B. Select 'By sequence num' in the Item box C. Select 'SMISC' in the first Comp box D. Enter SMISC,6 in the second Comp box E. Click 'OK'

This will save all of the bending moment data at the left hand side (I side) of each element. Now we need to find the bending moment data at the right hand side (J side) of each element.

Again, click 'Add...' in the 'Element Table Data' window. A. Enter JMoment as the 'User label for item' - again, this will give a name to the data B. Same as above C. Same as above D. For step D, enter SMISC,12 in the second Comp box E. Click 'OK'

Click 'Close' in the 'Element Table Data' window and close the 'Element Table' Menu. Select Plot Results > Contour Plot > Line Elem Res...

From the 'Plot Line-Element Results' window, select 'IMOMENT' from the pull down menu for



LabI, and 'JMOMENT' from the pull down menu for LabJ. Click 'OK'. Note again that you can modify the intervals for the contour plot.

Now, you can double check these solutions analytically. Note that the line between the I and J point is a linear interpolation.

Before the explanation of the above steps, enter help pipe16 in the command line as shown below and then hit enter.

Briefly read the ANSYS documentation which appears, pay particular attention to the Tables near the end of the document (shown below).

Table 1. PIPE16 Item, Sequence Numbers, and Definitions for the ETABLE Commands

node I

name item e DefinitionMFORX SMISC 1 Member

forces at the node

MFORY SMISC 2MFORZ SMISC 3MMOMX SMISC 4 Member

moments at the node

MMOMY SMISC 5MMOMZ SMISC 6



Note that SMISC 6 (which we used to obtain the values at node I) correspond to MMOMZ - the Member moment for node I. The value of 'e' varies with different Element Types, therefore you must check the ANSYS Documentation files for each element to determine the appropriate SMISC corresponding to the plot you wish to generate.

Command File Mode of Solution

The above example was solved using the Graphical User Interface (or GUI) of ANSYS. This problem can also been solved using the ANSYS command language interface. To see the benefits of the command line clear your current file:

From the Utility menu select: File > Clear and Start New Ensure that 'Read File' is selected then click 'OK' select 'yes' in the following window.

Copy the following code into the command line, then hit enter. Note that the text following the "!" are comments.

/PREP7 ! Preprocessor K,1,0,0,0, ! Keypoint, 1, x, y, z K,2,500,0,0, ! Keypoint, 2, x, y, z L,1,2 ! Line from keypoint 1 to 2 !* ET,1,PIPE16 ! Element Type = pipe 16 KEYOPT,1,6,1 ! This is the changed option to give the extra force and moment ou!* R,1,25,2, ! Real Constant, Material 1, Outside Diameter, Wall thickness !* MP,EX,1,70000 ! Material Properties, Young's Modulus, Material 1, 70000 MPa MP,PRXY,1,0.33 ! Material Properties, Major Poisson's Ratio, Material 1, 0.33 !* LESIZE,ALL,20 ! Element sizes, all of the lines, 20 mm LMESH,1 ! Mesh the lines FINISH ! Exit preprocessor /SOLU ! Solution ANTYPE,0 ! The type of analysis (static) !* DK,1, ,0, ,0,ALL ! Apply a Displacement to Keypoint 1 to all DOF FK,2,FY,-100 ! Apply a Force to Keypoint 2 of -100 N in the y direction /STATUS,SOLU SOLVE ! Solve the problem FINISH

Note that you have now finished Postprocessing and the Solution Phase with just these few lines of code. There are codes to complete the Postprocessing but we will review these later.

Bicycle Example Now we will return to the analysis of the bike frame. The steps which you completed in the verification example will not be explained in great detail, therefore use the verification example as a reference as required. We will be combining the use of the Graphic User Interface (GUI) with the use of command lines.

Recall the geometry and dimensions of the bicycle frame:



Preprocessing: Defining the Problem 1. Clear any old ANSYS files and start a new file

Utility Menu > File > Clear and Start New

2. Give the Example a Title Utility menu > File > Change Title

3. Defining Some Variables

We are going to define the vertices of the frame using variables. These variables represent the various lengths of the bicycle members. Notice that by using variables like this, it is very easy to set up a parametric description of your model. This will enable us to quickly redefine the frame should changes be necessary. The quickest way to enter these variables is via the 'ANSYS Input' window which was used above to input the command line codes for the verification model. Type in each of the following lines followed by Enter.

x1 = 500 x2 = 825 y1 = 325 y2 = 400 z1 = 50

4. Enter Keypoints

For this space frame example, these keypoints are the frame vertices.

We are going to define 6 keypoints for this structure as given in the following table (these keypoints are depicted by the circled numbers in the above figure):

keypointcoordinate

x y z



Now instead of using the GUI window we are going to enter code into the 'command line'. First, open the 'Preprocessor Menu' from the 'ANSYS Main Menu'. The preprocessor menu has to be open in order for the preprocessor commands to be recognized. Alternatively, you can type /PREP7 into the command line. The command line format required to enter a keypoint is as follows:

K, NPT, X, Y, Z

where, each Abbreviation is representative of the following:

Keypoint, Reference number for the keypoint, coords x/y/z

For a more detailed explanation, type help k into the command line

For example, to enter the first keypoint type:

K,1,0,y1,0

into the command line followed by Enter.

As with any programming language, you may need to add comments. The exclamation mark indicates that anything following it is commented out. ie - for the second keypoint you might type:

K,2,0,y2,0 ! keypoint, #, x=0, y=y2, z=0

Enter the 4 remaining keypoints (listed in the table above) using the command line

Now you may want to check to ensure that you entered all of the keypoints correctly: Utility Menu > List > Keypoints > Coordinates only (Alternatively, type 'KLIST' into the command line)

If there are any keypoints which need to be re-entered, simply re-enter the code. A previously defined keypoint of the same number will be redefined. However, if there is one that needs to be deleted simply enter the following code:

1 0 y1 0

2 0 y2 0

3 x1 y2 0

4 x1 0 0

5 x2 0 z1

6 x2 0 -z1



KDELE,#

where # corresponds to the number of the keypoint.

In this example, we defined the keypoints by making use of previously defined variables like y1 = 325. This was simply used for convenience. To define keypoint #1, for example, we could have alternatively used the coordinates x = 0, y = 325, z = 0.

5. Changing Orientation of the Plot

To get a better view of our view of our model, we'll view it in an isometric view:

Select Utility menu bar > PlotCtrls > Pan, Zoom, Rotate...'

6. Create Lines

We will be joining the following keypoints together:

In the window that appears (shown left), you have many controls. Try experimenting with them. By turning on the dynamic mode (click on the checkbox beside 'Dynamic Mode') you can use the mouse to drag the image, translating and rotating it on all three axes.

To get an isometric view, click on 'Iso' (at the top right). You can either leave the 'Pan, Zoom, Rotate' window open and move it to an empty area on the screen, or close it if your screen is already cluttered.

linekeypoint

1st 2nd

1 1 2

2 2 3

3 3 4

Again, we will use the command line to create the lines. The command format to creastraight line looks like:

L, P1, P2 Line, Keypoint at the beginning of the line, Keypoint at the end o

For example, to obtain the first line, I would write: ' L,1,2 '



Enter the remaining lines until you get a picture like that shown below.

Again, check to ensure that you entered all of the lines correctly: type ' LLIST ' into the command line

If there are any lines which need to be changed, delete the line by typing the following code: ' LDELE,# ' where # corresponds to the reference number of the line. (This can be obtained from the list of lines). And then re-enter the line (note: a new reference number will be assigned)

You should obtain the following:

7. Define the Type of Element Preprocessor > Element Type > Add/Edit/Delete > Add

As in the verification model, define the type of element (pipe16). As in the verification model, don't forget to change Option K6 'Include Output' to obtain extra force and moment output.

8. Define Geometric Properties Preprocessor > Real Constants > Add/Edit/Delete

Now specify geometric properties for the elements

4 1 4

5 3 5

6 4 5

7 3 6

8 4 6

Note: unlike 'Keypoints', 'Lines' will automatically assign themselves the next availabreference number.



Outside diameter OD: 25 Wall thickness TKWALL: 2


To set Young's Modulus and Poisson's ratio, we will again use the command line. (ensure that the preprocessor menu is still open - if not open it by clicking Preprocessor in the Main Menu)

MP, LAB, MAT, C0 Material Property,Valid material property label, Material Reference Number, v

To enter the Elastic Modulus (LAB = EX) of 70000 MPa, type: ' MP,EX,1,70000 '

To set Poisson's ratio (PRXY), type ' MP,PRXY,1,0.33 '

10. Mesh Size

As in the verification model, set the element length to 20 mm Preprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines

11. Mesh

Now the frame can be meshed. In the 'Preprocessor' menu select 'Mesh' > 'Lines' and click 'Pick All' in the 'Mesh Lines' Window

Saving Your Job Utility Menu > File > Save as...

Solution Phase: Assigning Loads and Solving Close the 'Preprocessor' menu and open up the 'Solution' menu (from the same 'ANSYS Main Menu').

1. Define Analysis Type Solution > Analysis Type > New Analysis... > Static


Once again, we will use the command line. We are going to pin (translational DOFs will be fixed) the first keypoint and constrain the keypoints corresponding to the rear wheel attachment locations in both the y and z directions. The following is the command line format to apply constraints at keypoints.

DK, KPOI, Lab, VALUE, VALUE2, KEXPND, Lab2, Lab3, Lab4, Lab5, Lab6 Displacement on K, K #, DOF label, value, value2, Expansion key, other DOF la

Not all of the fields are required for this example, therefore when entering the code certain fields will be empty. For example, to pin the first keypoint enter:

DK,1,UX,0,,,UY,UZ

The DOF labels for translation motion are: UX, UY, UZ. Note that the 5th and 6th fields are empty. These



correspond to 'value2' and 'the Expansion key' which are not required for this constraint. Also note that all three of the translational DOFs were constrained to 0. The DOFs can only be contrained in 1 command line if the value is the same.

To apply the contraints to Keypoint 5, the command line code is:

DK,5,UY,0,,,UZ

Note that only UY and UZ are contrained to 0. UX is not constrained. Again, note that the 5th and 6th fields are empty because they are not required.

Apply the constraints to the other rear wheel location (Keypoint 6 - UY and UZ). Now list the constraints ('DKLIST') and verify them against the following:

If you need to delete any of the constraints use the following command: 'DKDELE, K, Lab' (ie 'DKDELE,1,UZ' would delete the constraint in the 'z' direction for Keypoint 1)

3. Apply Loads

We will apply vertical downward loads of 600N at the seat post location (keypoint 3) and 200N at the pedal crank location (keypoint 4). We will use the command line to define these loading conditions.

FK, KPOI, Lab, value, value2 Force loads at keypoints, K #, Force Label directions (FX, FY, FZ), value1, value2 (i

To apply a force of 600N downward at keypoint 3, the code should look like this: ' FK,3,FY,-600 '

Apply both the forces and list the forces to ensure they were inputted correctly (FKLIST).

If you need to delete one of the forces, the code looks like this: 'FKDELE, K, Lab' (ie 'FKDELE,3,FY' would delete the force in the 'y' direction for Keypoint 3)




4. Solving the System Solution > Solve > Current LS

Postprocessing: Viewing the Results To begin Postprocessing, open the 'General Postproc' Menu

1. Deformation Plot Results > Deformed Shape... 'Def + undef edge'



You may want to try plotting this from different angles to get a better idea what's going on by using the 'Pan-Zoom-Rotate' menu that was earlier outlined. Try the 'Front' view button (Note that the views of 'Front', 'Left', 'Back', etc depend on how the object was first defined). Your screen should look like the plot below:

2. Deflections



Now let's take a look at some actual deflections in the frame. The deflections have been calculated at the nodes of the model, so the first thing we'll do is plot out the nodes and node numbers, so we know what node(s) we're after.

Go to Utility menu > PlotCtrls > Numbering... and turn on 'Node numbers'. Turn everything else off.

Note the node numbers of interest. Of particular interest are those nodes where the constraints were applied to see if their displacements/rotations were indeed fixed to zero. Also note the node numbers of the seat and crank locations.

List the Nodal Deflections (Main Menu > General Postproc > List Results > Nodal Solution...'). Are the displacements and rotations as you expected?

Plot the deflection as well. General Postproc > Plot Results > (-Contour Plot-) Nodal Solution select 'DOF solution' and 'USUM' in the window

Don't forget to use more useful intervals.

3. Element Forces

We could also take a look at the forces in the elements in much the same way:

Select 'Element Solution...' from the 'List Results' menu. Select 'Nodal force data' and 'All forces' from the lists displayed. Click on 'OK'. For each element in the model, the force/moment values at each of the two nodes per element will be displayed. Close this list window when you are finished browsing.



Then close the 'List Results' menu.

4. Stresses

As shown in the cantilever beam example, use the Element Table to gain access to derived stresses.

General Postproc > Element Table > Define Table ... Select 'Add' Select 'Stress' and 'von Mises' Element Table > Plot Elem Table

Again, select appropriate intervals for the contour plot

5. Bending Moment Diagrams

As shown previously, the bending moment diagram can be produced.

Select Element Table > Define Table... to define the table (remember SMISC,6 and SMISC,12)

And, Plot Results > Line Elem Res... to plot the data from the Element Table



Command File Mode of Solution The above example was solved using a mixture of the Graphical User Interface (or GUI) and the command language interface of ANSYS. This problem has also been solved using the ANSYS command language interface that you may want to browse. Open the file and save it to your computer. Now go to 'File > Read input from...' and select the file.

Quitting ANSYS To quit ANSYS, select 'QUIT' from the ANSYS Toolbar or select 'Utility Menu'/'File'/'Exit...'. In the dialog box that appears, click on 'Save Everything' (assuming that you want to) and then click on 'OK'.




Introduction This tutorial is the second of three basic tutorials created to illustrate commom features in ANSYS. The plane stress bracket tutorial builds upon techniques covered in the first tutorial (3D Bicycle Space Frame), it is therefore essential that you have completed that tutorial prior to beginning this one.

The 2D Plane Stress Bracket will introduce boolean operations, plane stress, and uniform pressure loading.

Problem Description

The problem to be modeled in this example is a simple bracket shown in the following figure. This bracket is to be built from a 20 mm thick steel plate. A figure of the plate is shown below.

This plate will be fixed at the two small holes on the left and have a load applied to the larger hole on the right.

Verification Example The first step is to simplify the problem. Whenever you are trying out a new analysis type, you need something (ie analytical solution or experimental data) to compare the results to. This way you can be sure that you've gotten the correct analysis type, units, scale factors, etc.

The simplified version that will be used for this problem is that of a flat rectangular plate with a hole shown in the following figure:

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/BT/Bracket/Bracket.html



1. Give the Simplified Version a Title Utility Menu > File > Change Title

2. Form Geometry

Boolean operations provide a means to create complicated solid models. These procedures make it easy to combine simple geometric entities to create more complex bodies. Subtraction will used to create this model, however, many other Boolean operations can be used in ANSYS.

a. Create the main rectangular shape

Instead of creating the geometry using keypoints, we will create an area (using GUI) Preprocessor > Create > (-Areas-) Rectangle > By 2 Corners



Fill in the window as shown above. This will create a rectangle where the bottom left corner has the coordinates 0,0,0 and the top right corner has the coordinates 200,100,0.

(Alternatively, the command line code for the above command is BLC4,0,0,200,100)

b. Create the circle Preprocessor > Create > (-Areas-) Circle > Solid Circle

Fill in the window as shown above. This will create a circle where the center has the



coordinates 100,50,0 (the center of the rectangle) and the radius of the circle is 20 mm.

(Alternatively, the command line code for the above command is CYL4,100,50,20 )

c. Subtraction

Now we want to subtract the circle from the rectangle. Prior to this operation, your image should resemble the following:

To perform the Boolean operation, from the Preprocessor menu select: (-Modeling-) Operate > (-Booleans-) Subtract > Areas >

At this point a 'Subtract Areas' window will pop up and the ANSYS Input window will display the following message: [ASBA] Pick or enter base areas from which to subtract (as shown below)

Therefore, select the base area (the rectangle) by clicking on it. Note: The selected area will turn pink once it is selected.

The following window may appear because there are 2 areas at the location you clicked.



Ensure that the entire rectangular area is selected (otherwise click 'Next') and then click 'OK'.

Click 'OK' on the 'Subtract Areas' window.

Now you will be prompted to select the areas to be subtracted, select the circle by clicking on it and then click 'OK'.

You should now have the following model:

(Alternatively, the command line code for the above step is ASBA,1,2)


It is now necessary to define the type of element to use for our problem:

Preprocessor Menu > Element Type > Add/Edit/Delete

Add the following type of element: Solid (under the Structural heading) and the Quad 82 element, as shown in the above figure.



PLANE82 is a higher order version of the two-dimensional, four-node element (PLANE42). PLANE82 is an eight noded quadrilateral element which is better suited to model curved boundaries.

For this example, we need a plane stress element with thickness, therefore

Click on the 'Options...' button. Click and hold the K3 button, and select 'Plane strs w/thk', as shown below.

(Alternatively, the command line code for the above step is ET,1,PLANE82 followed by KEYOPT,1,3,3)


As in previous examples Preprocessor menu > Real Constants > Add/Edit/Delete

Enter a thickness of 20 as shown in the figure below. This defines a plate thickness of 20mm)



(Alternatively, the command line code for the above step is R,1,20)

5. Element Material Properties As shown in previous examples, select Preprocessor > Material Props > Material models > Structural > Linear > Elastic > Isotropic

We are going to give the properties of Steel. Enter the following when prompted:

(Alternatively, the command line code for the above step is MP,EX,1,200000 followed by MP,PRXY,1,0.3)

6. Mesh Size

To tell ANSYS how big the elements should be, Preprocessor > (-Meshing-) Size Cntrls > (-Areas-) All Areas

Select an element edge length of 25. We will return later to determine if this was adequate for the problem.

(Alternatively, the command line code for the above step is AESIZE,ALL,25,)

7. Mesh

Now the frame can be meshed. In the 'Preprocessor' menu select Mesh > (-Areas-) Free and select the area when prompted

(Alternatively, the command line code for the above step is AMESH,ALL)

You should now have the following:

EX 200000PRXY 0.3





You have now defined your model. It is now time to apply the load(s) and constraint(s) and solve the the resulting system of equations.


Ensure that a Static Analysis will be performed (Solution > New Analysis).

(Alternatively, the command line code for the above step is ANTYPE,0)


As shown previously, the left end of the plate is fixed. In the Solution > (-Loads-) Apply > (-Structural-) Displacement > 'On Lines'

Select the left end of the plate and click on 'Apply' in the 'Apply U,ROT on Lines' window.

Fill in the window as shown below.



This location is fixed which means that all DOF's are constrained. Therefore, select 'All DOF' by clicking on it and enter '0' in the Value field as shown above.

You will see some blue triangles in the graphics window indicating the displacement contraints.

(Alternatively, the command line code for the above step is DL,4,,ALL,0)

3. Apply Loads

As shown in the diagram, there is a load of 20N/mm distributed on the right hand side of the plate. To apply this load:

Solution > (-Loads-) Apply > (-Structural-) Pressure > On Lines

When the window appears, select the line along the right hand edge of the plate and click 'OK'

Calculate the pressure on the plate end by dividing the distributed load by the thickness of the plate (1 MPa).

Fill in the "Apply PRES on lines" window as shown below. NOTE: The pressure is uniform along the surface of the plate, therefore the last field is left blank. The pressure is acting away from the surface of the plate, and is therefore defined as a negative pressure.




4. Solving the System Solution > (-Solve-) Current LS


1. Hand Calculations

Now, since the purpose of this exercise was to verify the results - we need to calculate what we should find.

Deflection: The maximum deflection occurs on the right hand side of the plate and was calculated to be 0.001 mm - neglecting the effects of the hole in the plate (ie - just a flat plate). The actual deflection of



the plate is therefore expected to be greater but in the same range of magnitude.

Stress: The maximum stress occurs at the top and bottom of the hole in the plate and was found to be 3.9 MPa.

2. Convergence using ANSYS

At this point we need to find whether or not the final result has converged. We will do this by looking at the deflection and stress at particular nodes while changing the size of the meshing element.

Since we have an analytical solution for the maximum stress point, we will check the stress at this point. First we need to find the node corresponding to the top of the hole in the plate. First plot and number the nodes

Utility Menu > Plot > Nodes Utility Menu > PlotCtrls > Numbering...

The plot should look similar to the one shown below. Make a note of the node closest to the top of the circle (ie. #49)

List the stresses (General Postproc > List Results > Nodal Solution > Stress, Principals SPRIN) and check the SEQV (Equivalent Stress / von Mises Stress) for the node in question. (as shown below in red)



The equivalent stress was found to be 2.9141 MPa at this point. We will use smaller elements to try to get a more accurate solution.

Resize Elements

a. To change the element size, we need to go back to the Preprocessor Menu Preprocessor > (-Meshing-) Size Cntrls > All Areas

now decrease the element edge length (ie 20)

b. Now remesh the model (Preprocessor > Mesh > (-Areas-) Free). Once you have selected the area and clicked 'OK' the following window will appear:

c. Click 'OK'. This will remesh the model using the new element edge length.

d. Solve the system again (note that the constraints need not be reapplied). ( Solution Menu > Current LS )

Repeat steps 'a' through 'd' until the model has converged. (note - the number of the node at the top



of the hole has most likely changed. It is essential that you plot the nodes again to select the appropriate node). Plot the stress/deflection at varying mesh sizes as shown below to confirm that convergence has occured.

Note the shapes of both the deflection and stress curves. As the number of elements in the mesh increases (ie - the element edge length decreases), the values converge towards a final solution.

The von Mises stress at the top of the hole in the plate was found to be approximatly 3.8 MPa. This is a mere 2.5% difference between the analytical solution and the solution found using ANSYS.

The approximate maximum displacement was found to be 0.0012 mm, this is 20% greater than the analytical solution. However, the analytical solution does not account for the large hole in the center of the plate which was expected to significantly increase the deflection at the end of the plate.

Therefore, the results using ANSYS were determined to be appropriate for the verification model.

3. Deformation

General Postproc > Plot Results > Deformed Shape > Def + undeformd to view both the deformed and the undeformed object.



Observe the locations of deflection.

4. Deflection General Postproc > Plot Results > Nodal Solution... Then select DOF solution, USUM in the window.

Alternatively, obtain these results as a list. (General Postproc > List Results > Nodal Solution...)



Are these results what you expected? Note that all translational degrees of freedom were constrained to zero at the left end of the plate.

5. Stresses General Postproc > Plot Results > Nodal Solution... Then select Stress, von Mises in the window.

You can list the von Mises stresses to verify the results at certain nodes General Postproc > List Results. Select Stress, Principals SPRIN


The above example was solved using the Graphical User Interface (or GUI) of ANSYS. This problem has also been solved using the ANSYS command language interface that you may want to browse. Open the file and save it to your computer. Now go to File > Read input from... and select the file.

Bracket Example Now we will return to the analysis of the bracket. A combination of GUI and the Command line will be used for this example.





Preprocessing: Defining the Problem 1. Give the Bracket example a Title

Utility Menu > File > Change Title

2. Form Geometry

Again, Boolean operations will be used to create the basic geometry of the Bracket.

a. Create the main rectangular shape

The main rectangular shape has a width of 80 mm, a height of 100mm and the bottom left corner is located at coordinates (0,0)

Ensure that the Preprocessor menu is open. (Alternatively type /PREP7 into the command line window)

Now instead of using the GUI window we are going to enter code into the 'command line'. Now I will explain the line required to create a rectangle:

BLC4, XCORNER, YCORNER, WIDTH, HEIGHT BLC4, X coord (bottom left), Y coord (bottom left), width, height

Therefore, the command line for this rectangle is BLC4,0,0,80,100

b. Create the circular end on the right hand side

The center of the circle is located at (80,50) and has a radius of 50 mm

The following code is used to create a circular area:



CYL4, XCENTER, YCENTER, RAD1 CYL4, X coord for the center, Y coord for the center, radius

Therefore, the command line for this circle is CYL4,80,50,50

c. Now create a second and third circle for the left hand side using the following dimensions:

d. Create a rectangle on the left hand end to fill the gap between the two small circles.

Your screen should now look like the following...

e. Boolean Operations - Addition

We now want to add these five discrete areas together to form one area.

parameter circle 2 circle 3

XCENTER 0 0

YCENTER 20 80

RADIUS 20 20

XCORNER -20

YCORNER 20

WIDTH 20

HEIGHT 60



To perform the Boolean operation, from the Preprocessor menu select: Operate > -Booleans- Add > Areas >

In the 'Add Areas' window, click on 'Pick All'

(Alternatively, the command line code for the above step is AADD,ALL)

You should now have the following model:

f. Create the Bolt Holes

We now want to remove the bolt holes from this plate.

Create the three circles with the parameters given below:

Now select Preprocessor > (-Modeling-) Operate > (-Booleans-) Subtract > Areas

.

Select the base areas from which to subract (the large plate that was created)

Next select the three circles that we just created. Click on the three circles that you just

parameter circle 1 circle 2 circle 3

WP X 80 0 0

WP Y 50 20 80

radius 30 10 10



created and click 'OK'.

(Alternatively, the command line code for the above step is ASBA,6,ALL)

Now you should have the following:


As in the verification model, PLANE82 will be used for this example

Preprocessor > Element Type > Add/Edit/Delete

Use the 'Options...' button to get a plane stress element with thickness

(Alternatively, the command line code for the above step is ET,1,PLANE82 followed by KEYOPT,1,3,3)

Under the Extra Element Output K5 select nodal stress.

4. Define Geometric Contants

Preprocessor > Real Constants > Add/Edit/Delete

Enter a thickness of 20mm.

(Alternatively, the command line code for the above step is R,1,20)




Preprocessor > Material Props > Material Library > Structural > Linear > Elastic > Isotropic

We are going to give the properties of Steel. Enter the following when prompted:

(The command line code for the above step is MP,EX,1,200000 followed by MP,PRXY,1,0.3)

6. Mesh Size

Preprocessor > (-Meshing-) Size Cntrls > (-Areas-) All Areas

Select an element edge length of 5. Again, we will need to make sure the model has converged.

(Alternatively, the command line code for the above step is AESIZE,ALL,5,)

7. Mesh

'Preprocessor' > 'Mesh' > (-Areas-) 'Free' and select the area when prompted

(Alternatively, the command line code for the above step is AMESH,ALL)



EX 200000PRXY 0.3



You have now defined your model. It is now time to apply the load(s) and constraint(s) and solve the the resulting system of equations.


'Solution' > 'New Analysis' and select 'Static'.

(Alternatively, the command line code for the above step is ANTYPE,0)


As illustrated, the plate is fixed at both of the smaller holes on the left hand side. Solution > (-Loads-) Apply > (-Structural-) Displacement > On Nodes

Instead of selecting one node at a time, you have the option of creating a box, polygon, or circle of which all the nodes in that area will be selected. For this case, select 'circle' as shown in the window below. (You may want to zoom in to select the points Utilty Menu / PlotCtrls / Pan, Zoom, Rotate...) Click at the center of the bolt hole and drag the circle out so that it touches all of the nodes on the border of the hole.

Click on 'Apply' in the 'Apply U,ROT on Lines' window and constrain all DOF's in the 'Apply U,ROT on Nodes' window.

Repeat for the second bolt hole.

3. Apply Loads



As shown in the diagram, there is a single vertical load of 1000N, at the bottom of the large bolt hole. Apply this force to the respective keypoint ( Solution > (-Loads-) Apply > (-Structural-) Force/Moment > On Keypoints Select a force in the y direction of -1000)



Solution > (-Solve-) Current LS

Post-Processing: Viewing the Results We are now ready to view the results. We will take a look at the deflected shape and the stress contours once we determine convergence has occured.

1. Convergence using ANSYS

At this point we need to find whether or not the final result has converged. Because we cannot solve for a solution analytically, we must try to

2. Deformation

General Postproc > Plot Results > Def + undeformed to view both the deformed and the undeformed object.

The graphic should be similar to the following



Observe the locations of deflection. Ensure that the deflection at the bolt hole is indeed 0.

3. Deflection

Alternatively, obtain these results as a list. (General Postproc > List Results > Nodal Solution...)

Are these results what you expected? Note that all translational degrees of freedom were constrained to zero at the bolt holes.



4. Stresses General Postproc > Plot Results > Nodal Solution... Then select von Mises Stress in the window.

You can list the von Mises stresses to verify the results at certain nodes General Postproc > List Results. Select Stress, Principals SPRIN

Command File Mode of Solution The above example was solved using the Graphical User Interface (or GUI) of ANSYS. This problem has also been solved using the ANSYS command language interface that you may want to browse. Open the file and save it to your computer. Now go to 'File > Read input from...' and select the file.

Quitting ANSYS To quit ANSYS, click 'QUIT' on the ANSYS Toolbar or select Utility Menu > File > Exit... In the window that appears, select 'Save Everything' (assuming that you want to) and then click 'OK'.



UofA ANSYS Tutorial

ANSYSUTILITIES

BASICTUTORIALS

INTERMEDIATETUTORIALS

ADVANCEDTUTORIALS

POSTPROC.TUTORIALS

COMMANDLINE FILES

PRINTABLEVERSION


Bicycle Space Frame


Modeling Tools

Solid Modeling

Index

Contributions

Comments

MecE 563

Mechanical Engineering

University of Alberta

ANSYS Inc.

Copyright © 2001University of Alberta

Modeling Tools in ANSYS

Introduction

This tutorial was completed using ANSYS 7.1 The purpose of the tutorial is to show several modelingtools available in ANSYS.

Three methods will be shown to create the meshed plate shown below.

Using Cutlines in ANSYS

Give example a TitleUtility Menu > File > Change Title .../title, meshing a plate using cutlines

1.

Open preprocessor menuANSYS Main Menu > Preprocessor/PREP7

2.

Create a block at origin (0,0) with a width and height of 1Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners...blc4,0,0,1,1

3.

Divide the area into 4 parts using 2 diagonal lines

Create a line Preprocessor > Modeling > Create > Lines > Lines > Straight Line

Select the top left keypoint and draw the line to the bottom right keypoint by clicking onthat keypoint

Now divide the area into 2 areas using the line by selecting Preprocessor > Modeling >Operate > Booleans > Divide > Area by Line

Select the area and click OK in the 'Divide Area by Line' window

Now select the line and click OK in the 'Divide Area by Line' window

The area is now divided into 2 as shown in the figure below. A warning may appear withthe statement "Line 5 is attached to 2 area(s) and cannot be deleted. This is expectedbecause the command which divides the area deletes the line used to create the area.However, in this case, the line is required to define the new areas. Click OK and ignore thewarning.

4.

Now we need to further divide the 2 areas to make 4 areas. Using the same method, createa line from the top right keypoint to the bottom left. Be sure to select both areas to divide,otherwise, you will have to create the line again to divide the second area.

Define the Type of Element5.

Preprocessor > Element Type > Add/Edit/Delete... > Add... > Structural Mass, Solid > Quad4node 42

For this problem we will use the PLANE42 (2D plane stress or plane strain) element. Thiselement has 4 nodes each with 2 degrees of freedom(translation along the X and Y axes).

Select Plane Stress with Thickness

In the Element Types window, select Options... and in Element behavior select Plane strs w/thk

Define Real Constants

Preprocessor > Real Constants > Add/Edit/Delete > Add... > OK

In the 'Real Constants for PLANE42' window, enter the thickness: 0.1

Define Element Material Properties

Preprocessor > Material Props > Material Models > Structural > Linear > Elastic > Isotropic

In the window that appears, enter the following geometric properties for steel:

Young's modulus EX: 200000i.Poisson's Ratio PRXY: 0.3ii.

Define Mesh Size

Preprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines...

To obtain the desired mesh we need to set NDIV to 2

Create a hardpoint

Preprocessor > Modeling > Create > Keypoints > Hard PT on line > Hard PT by ratio

For demonstration purposes only, we are going to create a hardpoint on one of the diagonal lines.Select the bottom right diagonal line and enter a ratio of 0.41 This will ensure the creation of anode at a location 41% down the line

Mesh the frame

Preprocessor > Meshing > Mesh > Areas > click 'Pick All'amesh,all

The mesh should then appear as shown below. Note that the node is not at the midway point on thebottom right diagonal line due to the hardpoint.

Merging Objects in ANSYS

Clear the memory and start a new modelUtility Menu > File > Clear & Start New .../clear

1.

Give example a TitleUtility Menu > File > Change Title .../title, meshing a plate by copying elements

2.


3.

Define KeypointsPreprocessor > Modeling > Create > Keypoints > In Active CS...K,#,x,y,z

We are going to define 3 keypoints as given in the following table:

Keypoint Coordinates (x,y)

1 (0,0)

2 (1,0)

3 (0.5,0.5)

4.

Create AreaPreprocessor > Modeling > Create > Areas > Arbitrary > Through KPsa,k1,k2,k3...

We are going to define an area through keypoints 1,2,3. Select keypoints 1,2 and 3 and thenselect 'OK'.

5.



As in the previous mesh, we will use the PLANE42 (2D plane stress or plane strain) element. Thiselement has 4 nodes each with 2 degrees of freedom(translation along the X and Y axes).










Define Mesh Size

Preprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines...

To obtain the desired mesh we need to set NDIV to 2

Mesh the area


Mirror the geometry

Create local coord system to mirror geom.Select: Utility Menu > WorkPlane > Local Coordinate Systems > Create Local CS > Atspecified LocWe are first going to mirror the geometry about the diagonal from node 1 to 4. Click on the lowerleft node (bottom corner) and select 'OK'As shown below, create a coordinate system rotated 45 degrees about Z

Next, mirror the geometrySelect: Preprocessor > Modeling > Reflect > Areas Click 'Pick All'In the window that appears select X-Z plane Y and click 'OK'. This will mirror the geometryabout the X-Z planeUse the same technique to obtain the full geometry

Re-activate the global coordinate system

Utility Menu > WorkPlane > Change Active CS to > Global Cartesiancsys,0

Plot Elements

Utility Menu > Plot > Elements

Your mesh should now appear as follows:

However, you are not done! If you plot the node numbers you will note that some duplicate nodes exist(created in mirroring).

Merge duplicate nodes/elements

Preprocessor > Numbering Ctrls > Merge Items > Allnummrg,all

Gluing Areas in ANSYS

Clear the memory and start a new modelUtility Menu > File > Clear & Start New .../clear

1.

Give example a TitleUtility Menu > File > Change Title .../title, meshing a plate by copying areas

2.


3.

Define KeypointsPreprocessor > Modeling > Create > Keypoints > In Active CS...K,#,x,y,z

We are going to define 7 keypoints as given in the following table:

Keypoint Coordinates (x,y)

1 (0,0)

2 (0.5,0)

3 (1,0)

4 (0.75,0.25)

5 (0.5,0.5)

6 (0.25,0.25)

7 (0.5,0.166667)

4.

Create AreaPreprocessor > Modeling > Create > Areas > Arbitrary > Through KPsa,k1,k2,k3...

Now we are going to define 3 areas; (1,2,7,6), (2,3,4,7), (4,5,6,7)

5.

Mirror the geometryAs shown in the previous section, create a local coordinate system and mirror the geometryUtility Menu > WorkPlane > Local Coordinate Systems > Create Local CS > Atspecified LocThen, mirror the geometry, select: Preprocessor > Modeling > Reflect > AreasDo this twice to obtain the full geometry

6.

Re-activate the global coordinate systemUtility Menu > WorkPlane > Change Active CS to > Global Cartesiancsys,0

7.

Glue the areas togetherPreprocessor > Modeling > Operate > Booleans > Glue > Areasaglue,all

We need to glue the areas together so that the areas are attached but that the subdividedareas remain to give us the elements we want

8.



As in the previous mesh, we will use the PLANE42 (2D plane stress or plane strain) element. Thiselement has 4 nodes each with 2 degrees of freedom(translation along the X and Y axes).










Define Mesh Size

Preprocessor > Meshing > Size Cntrls > ManualSize > Areas > All Areas...

To obtain the desired mesh we need to set SIZE to 1

Mesh the area


And again we obtain the desired mesh:


Introduction This tutorial is the last of three basic tutorials devised to illustrate commom features in ANSYS. Each tutorial builds upon techniques covered in previous tutorials, it is therefore essential that you complete the tutorials in order.

The Solid Modelling Tutorial will introduce various techniques which can be used in ANSYS to create solid models. Filleting, extrusion/sweeping, copying, and working plane orientation will be covered in detail.

Two Solid Models will be created within this tutorial.

Problem Description A We will be creating a solid model of the pulley shown in the following figure.

Geometry Generation

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/BT/Solid/Solid.html


We will create this model by first tracing out the cross section of the pulley and then sweeping this area about the y axis.

Creation of Cross Sectional Area

1. Create 3 Rectangles Main Menu > Preprocessor > (-Modeling-) Create > Rectangle > By 2 Corners BLC4, XCORNER, YCORNER, WIDTH, HEIGHT

The geometry of the rectangles:


2. Add the Areas Main Menu > Preprocessor > (-Modeling-) Operate > (-Boolean-) Add > Areas AADD, ALL

ANSYS will label the united area as AREA 4 and the previous three areas will be deleted.

3. Create the rounded edges using circles Preprocessor > (-Modeling-) Create > (-Areas-) Circle > Solid circles CYL4,XCENTER,YCENTER,RAD

The geometry of the circles:

Rectangle 1 Rectangle 2 Rectangle 3WP X (XCORNER) 2 3 8WP Y (YCORNER) 0 2 0WIDTH 1 5 0.5HEIGHT 5.5 1 5

Circle 1 Circle 2WP X (XCENTER) 3 8.5WP Y (YCENTER) 5.5 0.2



4. Subtract the large circle from the base Preprocessor > Operate > Subtract > Areas ASBA,BASE,SUBTRACT

5. Copy the smaller circle for the rounded edges at the top Preprocessor > (-Modeling-) Copy > Areas

Click on the small circle and then on OK.

The following window will appear. It asks for the x,y and z offset of the copied area. Enter the y offset as 4.6 and then click OK.

Copy this new area now with an x offset of -0.5

You should obtain the following

RADIUS 0.5 0.2



6. Add the smaller circles to the large area. Preprocessor > Operate > Add > Areas AADD,ALL

7. Fillet the inside edges of the top half of the area Preprocessor > Create > (-Lines-) Line Fillet

Select the two lines shown below and click on OK.

The following window will appear prompting for the fillet radius. Enter 0.1



Follow the same procedure and create a fillet with the same radius between the following lines

8. Create the fillet areas

As shown below, zoom into the fillet radius and plot and number the lines.



Preprocessor > (-Modeling-) Create > (-Areas-) Arbitrary > By Lines

Select the lines as shown below

Repeat for the other fillet

9. Add all the areas together Preprocessor > Operate > Add > Areas AADD,ALL

10. Plot the areas (Utility Menu > Plot - Areas)

Sweep the Cross Sectional Area

Now we need to sweep the area around a y axis at x=0 and z=0 to create the pulley.

1. Create two keypoints defining the y axis Create keypoints at (0,0,0) and (0,5,0) and number them 1001 and 1002 respectively. (K,#,X,Y,Z)

2. By default the graphics will now show all keypoints. Plot Areas

3. Sweep the area about the y axis



Preprocessor > (-Modeling-) Operate > Extrude > (-Areas-) About axis

You will first be prompted to select the areas to be swept so click on the area.

Then you will be asked to enter or pick two keypoints defining the axis.

Plot the Keypoints (Utility Menu > Plot > Keypoints. Then select the following two keypoints

The following window will appear prompting for sweeping angles. Click on OK.

You should now see the following in the graphics screen.



Create Bolt Holes

1. Change the Working Plane

By default, the working plane in ANSYS is located on the global Cartesian X-Y plane. However, for us to define the bolt holes, we need to use a different working plane. There are several ways to define a working plane, one of which is to define it by three keypoints.

Create the following Keypoints

Switch the view to top view and plot only keypoints.

2. Align the Working Plane with the Keypoints Utility Menu > WorkPlane > Align WP with > Keypoints +

Select Keypoints 2001 then 2002 then 2003 IN THAT ORDER. The first keypoint (2001) defines the origin of the working plane coordinate system, the second keypoint (2002) defines the x-axis orientation, while the third (2003) defines the orientation of the working plane. The following warning will appear when selecting the keypoint at the origin as there are more than one in this location.

X Y Z#2001 0 3 0#2002 1 3 0#2003 0 3 1



Just click on 'Next' until the one selected is 2001.

Once you have selected the 3 keypoints and clicked 'OK' the WP symbol (green) should appear in the Graphics window. Another way to make sure the active WP has moves is:

Utility Menu > WorkPlane > Show WP Status

note the origin of the working plane. By default those values would be 0,0,0.

3. Create a Cylinder (solid cylinder) with x=5.5 y=0 r=0.5 depth=1 You should see the following in the graphics screen



We will now copy this volume so that we repeat it every 45 degrees. Note that you must copy the cylinder before you use boolean operations to subtract it because you cannot copy an empty space.

4. We need to change active CS to cylindrical Y Utility Menu > WorkPlane > Change Active CS to > Global Cylindrical Y This will allow us to copy radially about the Y axis

5. Create 8 bolt Holes Preprocessor > Copy > Volumes

Select the cylinder volume and click on OK. The following window will appear; fill in the blanks as shown,



Youi should obtain the following model,

Subtract the cylinders from the pulley hub (Boolean operations) to create the boltholes. This will result in the following completed structure:




Problem Description B We will be creating a solid model of the Spindle Base shown in the following figure.

Geometry Generation



We will create this model by creating the base and the back and then the rib.

Create the Base

1. Create the base rectangle

2. Create the curved edge (using keypoints and lines to create an area)

Create the following keypoints


Create arcs joining the keypoints Main Menu > Preprocessor > (-Modeling-) Create > (-Lines-) Arcs > By End KPs & Rad

Select keypoints 4 and 5 (either click on them or type 4,5 into the command line) when prompted.

Select Keypoint 7 as the center-of-curvature when prompted.

Enter the radius of the arc (20) in the 'Arc by End KPs & Radius' window

Repeat to create an arc from keypoints 1 and 6

WP X (XCORNER) WP Y (YCORNER) WIDTH HEIGHT0 0 109 102

X Y ZKeypoint 5 -20 82 0Keypoint 6 -20 20 0Keypoint 7 0 82 0Keypoint 8 0 20 0



(Alternatively, type LARC,4,5,7,20 followed by LARC,1,6,8,20 into the command line)

Create a line from Keypoint 5 to 6 Main Menu > Preprocessor > (-Modeling-) Create > (-Lines-) Lines > Straight Line L,5,6

Create an Arbitrary area within the bounds of the lines Main Menu > Preprocessor > (-Modeling-) Create > (-Areas-) Arbitrary > By Lines AL,4,5,6,7

Combine the 2 areas into 1 (to form Area 3) Main Menu > Preprocessor > (-Modeling-) Operate > (-Booleans-) Add > Volumes AADD,1,2

You should obtain the following image:

3. Create the 4 holes in the base

We will make use of the 'copy' feature in ANSYS to create all 4 holes

Create the bottom left circle (XCENTER=0, YCENTER=20, RADIUS=10)

Copy the area to create the bottom right circle (DX=69) (AGEN,# Copies (include original),Area#,Area2# (if 2 areas to be copied),DX,DY,DZ)

Copy both circles to create the upper circles (DY=62)

Subtract the three circles from the main base (ASBA,3,ALL)




4. Extrude the base Preprocessor > (-Modeling-) Operate > Extrude > (-Areas-) Along Normal

The following window will appear once you select the area

Fill in the window as shown (length of extrusion = 26mm). Note, to extrude the area in the negative z direction you would simply enter -26.

(Alternatively, type VOFFST,6,26 into the command line)

Create the Back

1. Change the working plane

As in the previous example, we need to change the working plane. You may have observed that geometry can only be created in the X-Y plane. Therefore, in order to create the back of the Spindle Base, we need to create a new working plane where the X-Y plane is parallel to the back. Again, we will define the working plane by aligning it to 3 Keypoints.




Align the working plane to the 3 keypoints

Recall when defining the working plane; the first keypoint defines the origin, the second keypoint defines the x-axis orientation, while the third defines the orientation of the working plane. (Alternatively, type KWPLAN,1,100,101,102 into the command line)

2. Create the back area

Create the base rectangle (XCORNER=0, YCORNER=0, WIDTH=102, HEIGHT=180)

Create a circle to obtain the curved top (XCENTER=51, YCENTER=180, RADIUS=51)

Add the 2 areas together

3. Extrude the area (length of extrusion = 26mm) Preprocessor > (-Modeling-) Operate > Extrude > (-Areas-) Along Normal VOFFST,27,26

4. Add the base and the back together

Add the two volumes together Preprocessor > (-Modeling-) Operate > (-Booleans-) Add > Volumes VADD,1,2

You should now have the following geometry

Note that the planar areas between the two volumes were not added together.

X Y Z#100 109 102 0#101 109 2 0#102 159 102 sqrt(3)/0.02



Add the planar areas together (don't forget the other side!) Preprocessor > (-Modeling-) Operate > (-Booleans-) Add > Areas AADD, Area 1, Area 2, Area 3

5. Create the Upper Cylinder

Create the outer cylinder (XCENTER=51, YCENTER=180, RADIUS=32, DEPTH=60) Preprocessor > (-Modeling-) Create > (-Volumes-) Cylinder > Solid Cylinder CYL4,51,180,32, , , ,60

Add the volumes together

Create the inner cylinder (XCENTER=51, YCENTER=180, RADIUS=18.5, DEPTH=60)

Subtract the volumes to obtain a hole

You should now have the following geometry:

Create the Rib

1. Change the working plane

First change the active coordinate system back to the global coordinate system (this will make it easier to align to the new coordinate system)

Utility Menu > WorkPlane > Align WP with > Global Cartesian

(Alternatively, type WPCSYS,-1,0 into the command line)


X Y Z#200 -20 61 26



Align the working plane to the 3 keypoints

Recall when defining the working plane; the first keypoint defines the origin, the second keypoint defines the x-axis orientation, while the third defines the orientation of the working plane. (Alternatively, type KWPLAN,1,200,201,202 into the command line)

2. Change active coordinate system

We now need to update the coordiante system to follow the working plane changes (ie make the new Work Plane origin the active coordinate)

Utility Menu > WorkPlane > Change Active CS to > Working Plane CSYS,4

3. Create the area

Create the keypoints corresponding to the vertices of the rib

Create the rib area through keypoints 200, 203, 204 Preprocessor > (-Modeling-) Create > (-Areas-) Arbitrary > Through KPs A,200,203,204

4. Extrude the area (length of extrusion = 20mm)

5. Add the volumes together


#201 0 61 26#202 -20 61 30

X Y Z#203 129-(0.57735*26) 0 0#204 129-(0.57735*26) + 38 sqrt(3)/2*76 0




Quitting ANSYS To quit ANSYS, select 'QUIT' from the ANSYS Toolbar or select 'Utility Menu'/'File'/'Exit...'. In the dialog box that appears, click on 'Save Everything' (assuming that you want to) and then click on 'OK'.



Effect of Self Weight on a Cantilever Beam

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to show the required steps to account for the weight of an object in ANSYS.

Loads will not be applied to the beam shown below in order to observe the deflection caused by the weight of the beam itself. The beam is to be made of steel with a modulus of elasticity of 200 GPa.

Preprocessing: Defining the Problem 1. Give example a Title

Utility Menu > File > Change Title ... /title, Effects of Self Weight for a Cantilever Beam

2. Open preprocessor menu ANSYS Main Menu > Preprocessor /PREP7

3. Define Keypoints Preprocessor > Modeling > Create > Keypoints > In Active CS... K,#,x,y,z

We are going to define 2 keypoints for this beam as given in the following table:

4. Create Lines Preprocessor > Modeling > Create > Lines > Lines > In Active Coord

Keypoint Coordinates (x,y,z)1 (0,0)2 (1000,0)

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/Density/Density.html


L,1,2

Create a line joining Keypoints 1 and 2

5. Define the Type of Element Preprocessor > Element Type > Add/Edit/Delete...

For this problem we will use the BEAM3 (Beam 2D elastic) element. This element has 3 degrees of freedom (translation along the X and Y axes, and rotation about the Z axis).

6. Define Real Constants Preprocessor > Real Constants... > Add...

In the 'Real Constants for BEAM3' window, enter the following geometric properties: i. Cross-sectional area AREA: 500

ii. Area moment of inertia IZZ: 4166.67 iii. Total beam height: 10

This defines a beam with a height of 10 mm and a width of 50 mm.

7. Define Element Material Properties Preprocessor > Material Props > Material Models > Structural > Linear > Elastic > Isotropic

In the window that appears, enter the following geometric properties for steel: i. Young's modulus EX: 200000

ii. Poisson's Ratio PRXY: 0.3

8. Define Element Density Preprocessor > Material Props > Material Models > Structural > Linear > Density

In the window that appears, enter the following density for steel: i. Density DENS: 7.86e-6

9. Define Mesh Size Preprocessor > Meshing > Size Cntrls > ManualSize > Lines > All Lines...

For this example we will use an element edge length of 100mm.

10. Mesh the frame Preprocessor > Meshing > Mesh > Lines > click 'Pick All'

Solution Phase: Assigning Loads and Solving 1. Define Analysis Type

Solution > Analysis Type > New Analysis > Static ANTYPE,0



2. Apply Constraints Solution > Define Loads > Apply > Structural > Displacement > On Keypoints

Fix keypoint 1 (ie all DOF constrained)

3. Define Gravity

It is necessary to define the direction and magnitude of gravity for this problem.

Select Solution > Define Loads > Apply > Structural > Inertia > Gravity...

The following window will appear. Fill it in as shown to define an acceleration of 9.81m/s2 in the y direction.

Note: Acceleration is defined in terms of meters (not 'mm' as used throughout the problem). This is because the units of acceleration and mass must be consistent to give the product of force units (Newtons in this case). Also note that a positive acceleration in the y direction stimulates gravity in the negative Y direction.

There should now be a red arrow pointing in the positive y direction. This indicates that an acceleration has been defined in the y direction. DK,1,ALL,0, ACEL,,9.8

The applied loads and constraints should now appear as shown in the figure below.



4. Solve the System Solution > Solve > Current LS SOLVE


Hand calculations were performed to verify the solution found using ANSYS:

The maximum deflection was shown to be 5.777mm

2. Show the deformation of the beam General Postproc > Plot Results > Deformed Shape ... > Def + undef edge PLDISP,2



As observed in the upper left hand corner, the maximum displacement was found to be 5.777mm. This is in agreement with the theortical value.




Application of Distributed Loads

Introduction This tutorial was completed using ANSYS 7.0. The purpose of this tutorial is to explain how to apply distributed loads and use element tables to extract data. Please note that this material was also covered in the 'Bicycle Space Frame' tutorial under 'Basic Tutorials'.

A distributed load of 1000 N/m (1 N/mm) will be applied to a solid steel beam with a rectangular cross section as shown in the figure below. The cross-section of the beam is 10mm x 10mm while the modulus of elasticity of the steel is 200GPa.

Preprocessing: Defining the Problem 1. Open preprocessor menu

/PREP7

2. Give example a Title Utility Menu > File > Change Title ... /title, Distributed Loading

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/Distributed/Distributed.h...


3. Create Keypoints Preprocessor > Modeling > Create > Keypoints > In Active CS K,#,x,y

We are going to define 2 keypoints (the beam vertices) for this structure as given in the following table:

4. Define Lines Preprocessor > Modeling > Create > Lines > Lines > Straight Line L,K#,K#

Create a line between Keypoint 1 and Keypoint 2.

5. Define Element Types Preprocessor > Element Type > Add/Edit/Delete...

For this problem we will use the BEAM3 element. This element has 3 degrees of freedom (translation along the X and Y axis's, and rotation about the Z axis). With only 3 degrees of freedom, the BEAM3 element can only be used in 2D analysis.



ii. Area Moment of Inertia IZZ: 833.333 iii. Total beam height HEIGHT: 10

This defines an element with a solid rectangular cross section 10mm x 10mm.





For this example we will use an element length of 100mm.


Keypoint Coordinates (x,y)1 (0,0)2 (1000,0)



10. Plot Elements Utility Menu > Plot > Elements

You may also wish to turn on element numbering and turn off keypoint numbering Utility Menu > PlotCtrls > Numbering ...




Pin Keypoint 1 (ie UX and UY constrained) and fix Keypoint 2 in the y direction (UY constrained).

3. Apply Loads

We will apply a distributed load, of 1000 N/m or 1 N/mm, over the entire length of the beam. Select Solution > Define Loads > Apply > Structural > Pressure > On Beams Click 'Pick All' in the 'Apply F/M' window. As shown in the following figure, enter a value of 1 in the field 'VALI Pressure value at node I' then click 'OK'.




Note: To have the constraints and loads appear each time you select 'Replot' you must change some settings. Select Utility Menu > PlotCtrls > Symbols.... In the window that appears, select 'Pressures' in the pull down menu of the 'Surface Load Symbols' section.




Postprocessing: Viewing the Results 1. Plot Deformed Shape

General Postproc > Plot Results > Deformed Shape PLDISP.2

2. Plot Principle stress distribution

As shown previously, we need to use element tables to obtain principle stresses for line elements.

1. Select General Postproc > Element Table > Define Table

2. Click 'Add...'

3. In the window that appears a. enter 'SMAXI' in the 'User Label for Item' section b. In the first window in the 'Results Data Item' section scroll down and select 'By sequence

num' c. In the second window of the same section, select 'NMISC, ' d. In the third window enter '1' anywhere after the comma

4. click 'Apply'

5. Repeat steps 2 to 4 but change 'SMAXI' to 'SMAXJ' in step 3a and change '1' to '3' in step 3d.

6. Click 'OK'. The 'Element Table Data' window should now have two variables in it.

7. Click 'Close' in the 'Element Table Data' window.

8. Select: General Postproc > Plot Results > Line Elem Res...



9. Select 'SMAXI' from the 'LabI' pull down menu and 'SMAXJ' from the 'LabJ' pull down menu

Note:

ANSYS can only calculate the stress at a single location on the element. For this example, we decided to extract the stresses from the I and J nodes of each element. These are the nodes that are at the ends of each element.

For this problem, we wanted the principal stresses for the elements. For the BEAM3 element this is categorized as NMISC, 1 for the 'I' nodes and NMISC, 3 for the 'J' nodes. A list of available codes for each element can be found in the ANSYS help files. (ie. type help BEAM3 in the ANSYS Input window).

As shown in the plot below, the maximum stress occurs in the middle of the beam with a value of 750 MPa.




NonLinear Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to outline the steps required to do a simple nonlinear analysis of the beam shown below.

There are several causes for nonlinear behaviour such as Changing Status (ex. contact elements), Material Nonlinearities and Geometric Nonlinearities (change in response due to large deformations). This tutorial will deal specifically with Geometric Nonlinearities .

To solve this problem, the load will added incrementally. After each increment, the stiffness matrix will be adjusted before increasing the load.

The solution will be compared to the equivalent solution using a linear response.


Utility Menu > File > Change Title ...

2. Create Keypoints Preprocessor > Modeling > Create > Keypoints > In Active CS

We are going to define 2 keypoints (the beam vertices) for this structure to create a beam with a length of 5 inches:


University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/NonLinear/NonLinear.ht...


3. Define Lines Preprocessor > Modeling > Create > Lines > Lines > Straight Line

Create a line between Keypoint 1 and Keypoint 2.


For this problem we will use the BEAM3 (Beam 2D elastic) element. This element has 3 degrees of freedom (translation along the X and Y axis's, and rotation about the Z axis). With only 3 degrees of freedom, the BEAM3 element can only be used in 2D analysis.


In the 'Real Constants for BEAM3' window, enter the following geometric properties: i. Cross-sectional area AREA: 0.03125

ii. Area Moment of Inertia IZZ: 4.069e-5 iii. Total beam height HEIGHT: 0.125

This defines an element with a solid rectangular cross section 0.25 x 0.125 inches.


In the window that appears, enter the following geometric properties for steel: i. Young's modulus EX: 30e6


If you are wondering why a 'Linear' model was chosen when this is a non-linear example, it is because this example is for non-linear geometry, not non-linear material properties. If we were considering a block of wood, for example, we would have to consider non-linear material properties.


For this example we will specify an element edge length of 0.1 " (50 element divisions along the line).

8. Mesh the frame Preprocessor > Meshing > Mesh > Lines > click 'Pick All' LMESH,ALL

Solution: Assigning Loads and Solving 1. Define Analysis Type



Solution > New Analysis > Static ANTYPE,0

2. Set Solution Controls

Select Solution > Analysis Type > Sol'n Control...

The following image will appear:

Ensure the following selections are made (as shown above)

A. Ensure Large Static Displacements are permitted (this will include the effects of large deflection in the results)

B. Ensure Automatic time stepping is on. Automatic time stepping allows ANSYS to determine appropriate sizes to break the load steps into. Decreasing the step size usually ensures better accuracy, however, this takes time. The Automatic Time Step feature will determine an appropriate balance. This feature also activates the ANSYS bisection feature which will allow recovery if convergence fails.

C. Enter 5 as the number of substeps. This will set the initial substep to 1/5 th of the total load.

The following example explains this: Assume that the applied load is 100 lb*in. If the Automatic Time Stepping was off, there would be 5 load steps (each increasing by 1/5 th of the total load):

20 lb*in 40 lb*in 60 lb*in 80 lb*in



100 lb*in

Now, with the Automatic Time Stepping is on, the first step size will still be 20 lb*in. However, the remaining substeps will be determined based on the response of the material due to the previous load increment.

D. Enter a maximum number of substeps of 1000. This stops the program if the solution does not converge after 1000 steps.

E. Enter a minimum number of substeps of 1.

F. Ensure all solution items are writen to a results file.

NOTE There are several options which have not been changed from their default values. For more information about these commands, type help followed by the command into the command line.


Fix Keypoint 1 (ie all DOFs constrained).

4. Apply Loads

Function Command Comments

Load Step KBC Loads are either linearly interpolated (ramped) from the one substep to another (ie - the load will increase from 10 lbs to 20 lbs in a linear fashion) or they are step functions (ie. the load steps directly from 10 lbs to 20 lbs). By default, the load is ramped. You may wish to use the stepped loading for rate-dependent behaviour or transient load steps.

Output OUTRES This command controls the solution data written to the database. By default, all of the solution items are written at the end of each load step. You may select only a specific iten (ie Nodal DOF solution) to decrease processing time.

Stress Stiffness

SSTIF This command activates stress stiffness effects in nonlinear analyses. When large static deformations are permitted (as they are in this case), stress stiffening is automatically included. For some special nonlinear cases, this can cause divergence because some elements do not provide a complete consistent tangent.

Newton Raphson

NROPT By default, the program will automatically choose the Newton-Raphson options. Options include the full Newton-Raphson, the modified Newton-Raphson, the previously computed matrix, and the full Newton-Raphson with unsymmetric matrices of elements.

Convergence Values

CNVTOL By default, the program checks the out-of-balance load for any active DOF.



Solution > Define Loads > Apply > Structural > Force/Moment > On Keypoints

Place a -100 lb*in moment in the MZ direction at the right end of the beam (Keypoint 2)


The following will appear on your screan for NonLinear Analyses

This shows the convergence of the solution.

General Postprocessing: Viewing the Results 1. View the deformed shape

General Postproc > Plot Results > Deformed Shape... > Def + undeformed PLDISP,1



2. View the deflection contour plot General Postproc > Plot Results > Contour Plot > Nodal Solu... > DOF solution, UY PLNSOL,U,Y,0,1

3. List Horizontal Displacement If this example is performed as a linear model there will be no nodal deflection in the horizontal direction due to the small deflections assumptions. However, this is not realistic for large deflections. Modeling the system non-linearly, these horizontal deflections are calculated by ANSYS. General Postproc > List Results > Nodal Solution...> DOF solution, UX



Other results can be obtained as shown in previous linear static analyses.




Graphical Solution Tracking

Introduction This tutorial was completed using ANSYS 7.0 This will act as an explanation of what the Graphical Solution Tracking plot is acutally describing. An example of such a plot is shown below and will be used throughout the explanation.

1. Title and Axis Labels The title of the graph is really just the time value of the last calculated iteration. In this example, the time at the end of the analysis was set to 1. This can be changed with the Time command before the Solve command is issued. For more information regarding setting the time value, and many other solution control option, see Chapter 8.5 of the Structural Analysis Guide in the Help file.

The x-axis is labelled Cumulative Iteration Number. As ANSYS steps through non-linear analysis, it uses a solver (Newton-Raphson, etc) that iterates to find a solution. If the problem is relatively linear, very few iterations will be required and thus the length of the graph will be small. However, if the solution is highly non-linear, or is not converging, many iterations will be required. The length of the graph in these cases can be quite long. Again, for more information about changing iteration settings, you can see Chapter 8.5 in the help file.

The y-axis is labelled Absolute Convergence Norm. In the case of a structural analysis, which this graph is taken from, this absolute convergence norm refers to non-normalized values (ie there are units associated with these values). Some analyses use normalized values. In reality it doesn't really matter because it is only a comparison that is going on. This is what will be explained next.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/GST/print.html


2. Curves and Legend As can be guessed from the legend labels, this graph relates to forces and moments. These values are graphed because they are the corresponding values in the solution vector for the DOF's that are active in the elements being used. If this graph were from a thermal analysis, the curves may be for temperature.

For each parameter, there are two curves plotted. For ease of explanation, we will look at the force curves.

The F CRIT curve refers to the convergence criteria force value. This value is equal to the product of VALUE x TOLER. The default value of VALUE is the square root of the sum of the squares (SRSS) of the applied loads, or MINREF (which defaults to 0.001), which ever is greater. This value can be changed using the CNVTOL command, which is discussed in the help file. The value of TOLER defaults to 0.5% for loads.

One may inquire why the F CRIT value increases as the number of iterations increases. This is because the analysis is made up of a number of substeps. In the case of a structural example, such as this, these substeps are basically portions of the total load being applied over time. For instance, a 100N load broken up with 20 substeps means 20, 5N loads will be applied consequtively until the entire 100N is applied. Thus, the F CRIT value at the start will be 1/20th of the final F CRIT value.

The F L2 curve refers to the L2 Vector Norm of the forces. The L2 norm is the SRSS of the force imbalances for all DOF's. In simpler terms, this is the SRSS of the difference between the calculated internal force at a particular DOF and the external force in that direction.

For each substep, ANSYS iterates until the F L2 value is below the F CRIT value. Once this occurs, it is deemed the solution is within tolerance of the correct solution and it moves on to the next substep. Generally, when the curves peak this is the start of a new substep. As can be seen in the graph above, a peak follow everytime the L2 value drops below the CRIT value, as expected.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/GST/print.html


Buckling

Introduction This tutorial was created using ANSYS 7.0 to solve a simple buckling problem.

It is recommended that you complete the NonLinear Tutorial prior to beginning this tutorial

Buckling loads are critical loads where certain types of structures become unstable. Each load has an associated buckled mode shape; this is the shape that the structure assumes in a buckled condition. There are two primary means to perform a buckling analysis:

1. Eigenvalue

Eigenvalue buckling analysis predicts the theoretical buckling strength of an ideal elastic structure. It computes the structural eigenvalues for the given system loading and constraints. This is known as classical Euler buckling analysis. Buckling loads for several configurations are readily available from tabulated solutions. However, in real-life, structural imperfections and nonlinearities prevent most real-world structures from reaching their eigenvalue predicted buckling strength; ie. it over-predicts the expected buckling loads. This method is not recommended for accurate, real-world buckling prediction analysis.

2. Nonlinear

Nonlinear buckling analysis is more accurate than eigenvalue analysis because it employs non-linear, large-deflection, static analysis to predict buckling loads. Its mode of operation is very simple: it gradually increases the applied load until a load level is found whereby the structure becomes unstable (ie. suddenly a very small increase in the load will cause very large deflections). The true non-linear nature of this analysis thus permits the modeling of geometric imperfections, load perterbations, material nonlinearities and gaps. For this type of analysis, note that small off-axis loads are necessary to initiate the desired buckling mode.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/Buckling/Buckling.html


This tutorial will use a steel beam with a 10 mm X 10 mm cross section, rigidly constrained at the bottom. The required load to cause buckling, applied at the top-center of the beam, will be calculated.

Eigenvalue Buckling Analysis


1. Open preprocessor menu /PREP7

2. Give example a Title Utility Menu > File > Change Title ... /title,Eigen-Value Buckling Analysis

3. Define Keypoints Preprocessor > Modeling > Create > Keypoints > In Active CS ... K,#,X,Y

We are going to define 2 Keypoints for this beam as given in the following table:

4. Create Lines

Keypoints Coordinates (x,y)1 (0,0)2 (0,100)



Preprocessor > Modeling > Create > Lines > Lines > In Active Coord L,1,2






ii. Area moment of inertia IZZ: 833.333 iii. Total Beam Height HEIGHT: 10






For this example we will specify an element edge length of 10 mm (10 element divisions along the line).



1. Define Analysis Type Solution > Analysis Type > New Analysis > Static ANTYPE,0

2. Activate prestress effects

To perform an eigenvalue buckling analysis, prestress effects must be activated.

You must first ensure that you are looking at the unabridged solution menu so that you can select



Analysis Options in the Analysis Type submenu. The last option in the solution menu will either be 'Unabridged menu' (which means you are currently looking at the abridged version) or 'Abriged Menu' (which means you are looking at the unabridged menu). If you are looking at the abridged menu, select the unabridged version.

Select Solution > Analysis Type > Analysis Options

In the following window, change the [SSTIF][PSTRES] item to 'Prestress ON', which ensures the stress stiffness matrix is calculated. This is required in eigenvalue buckling analysis.


Fix Keypoint 1 (ie all DOF constrained).

4. Apply Loads Solution > Define Loads > Apply > Structural > Force/Moment > On Keypoints

The eignenvalue solver uses a unit force to determine the necessary buckling load. Applying a load other than 1 will scale the answer by a factor of the load.

Apply a vertical (FY) point load of -1 N to the top of the beam (keypoint 2).





6. Exit the Solution processor Close the solution menu and click FINISH at the bottom of the Main Menu. FINISH

Normally at this point you enter the postprocessing phase. However, with a buckling analysis you must re-enter the solution phase and specify the buckling analysis. Be sure to close the solution menu and re-enter it or the buckling analysis may not function properly.

7. Define Analysis Type Solution > Analysis Type > New Analysis > Eigen Buckling ANTYPE,1

8. Specify Buckling Analysis Options


Complete the window which appears, as shown below. Select 'Block Lanczos' as an extraction method and extract 1 mode. The 'Block Lanczos' method is used for large symmetric eigenvalue problems and uses the sparse matrix solver. The 'Subspace' method could also be used, however it tends to converge slower as it is a more robust solver. In more complex analyses the Block Lanczos method may not be adequate and the Subspace method would have to be used.




10. Exit the Solution processor Close the solution menu and click FINISH at the bottom of the Main Menu. FINISH

Again it is necessary to exit and re-enter the solution phase. This time, however, is for an expansion pass. An expansion pass is necessary if you want to review the buckled mode shape(s).

11. Expand the solution

Select Solution > Analysis Type > Expansion Pass... and ensure that it is on. You may have to select the 'Unabridged Menu' again to make this option visible.

Select Solution > Load Step Opts > ExpansionPass > Single Expand > Expand Modes ...

Complete the following window as shown to expand the first mode





1. View the Buckling Load

To display the minimum load required to buckle the beam select General Postproc > List Results > Detailed Summary. The value listed under 'TIME/FREQ' is the load (41,123), which is in Newtons for this example. If more than one mode was selected in the steps above, the corresponding loads would be listed here as well. /POST1 SET,LIST

2. Display the Mode Shape

Select General Postproc > Read Results > Last Set to bring up the data for the last mode calculated.

Select General Postproc > Plot Results > Deformed Shape


The above example was solved using a mixture of the Graphical User Interface (or GUI) and the command language interface of ANSYS. This problem has also been solved using the ANSYS command language interface that you may want to browse. Open the file and save it to your computer. Now go to 'File > Read input from...' and select the file.



Non-Linear Buckling Analysis Ensure that you have completed the NonLinear Tutorial prior to beginning this portion of the tutorial


1. Open preprocessor menu /PREP7

2. Give example a Title Utility Menu > File > Change Title ... /TITLE, Nonlinear Buckling Analysis

3. Create Keypoints Preprocessor > Modeling > Create > Keypoints > In Active CS K,#,X,Y

We are going to define 2 keypoints (the beam vertices) for this structure to create a beam with a length of 100 millimeters:


Create a line between Keypoint 1 and Keypoint 2. L,1,2


For this problem we will use the BEAM3 (Beam 2D elastic) element. This element has 3 degrees of freedom (translation along the X and Y axis's, and rotation about the Z axis). With only 3 degrees of freedom, the BEAM3 element can only be used in 2D analysis.



ii. Area Moment of Inertia IZZ: 833.333 iii. Total beam height HEIGHT: 10

This defines an element with a solid rectangular cross section 10 x 10 millimeters.

7. Define Element Material Properties







8. Define Mesh Size Preprocessor > Meshing > Size Cntrls > Lines > All Lines...

For this example we will specify an element edge length of 1 mm (100 element divisions along the line). ESIZE,1


Solution: Assigning Loads and Solving

1. Define Analysis Type Solution > New Analysis > Static ANTYPE,0




Ensure the following selections are made under the 'Basic' tab (as shown above)








F. Ensure all solution items are writen to a results file.

Ensure the following selection is made under the 'Nonlinear' tab (as shown below)

A. Ensure Line Search is 'On'. This option is used to help the Newton-Raphson solver converge.

B. Ensure Maximum Number of Iterations is set to 1000







Place a -50,000 N load in the FY direction on the top of the beam (Keypoint 2). Also apply a -250 N load in the FX direction on Keypoint 2. This horizontal load will persuade the beam to buckle at the minimum buckling load.

The model should now look like the window shown below.


The following will appear on your screen for NonLinear Analyses




General Postprocessing: Viewing the Results

1. View the deformed shape

To view the element in 2D rather than a line: Utility Menu > PlotCtrls > Style > Size and Shape and turn 'Display of element' ON (as shown below).



General Postproc > Plot Results > Deformed Shape... > Def + undeformed PLDISP,1



View the deflection contour plot General Postproc > Plot Results > Contour Plot > Nodal Solu... > DOF solution, UY PLNSOL,U,Y,0,1


Time History Postprocessing: Viewing the Results



As shown, you can obtain the results (such as deflection, stress and bending moment diagrams) the same way you did in previous examples using the General Postprocessor. However, you may wish to view time history results such as the deflection of the object over time.

1. Define Variables

Select: Main Menu > TimeHist Postpro. The following window should open automatically.

If it does not open automatically, select Main Menu > TimeHist Postpro > Variable Viewer

Click the add button in the upper left corner of the window to add a variable.

Double-click Nodal Solution > DOF Solution > Y-Component of displacement (as shown below) and click OK. Pick the uppermost node on the beam and click OK in the 'Node for Data' window.



To add another variable, click the add button again. This time select Reaction Forces > Structural Forces > Y-Component of Force. Pick the lowermost node on the beam and click OK.

On the Time History Variable window, click the circle in the 'X-Axis' column for FY_3. This will make the reaction force the x-variable. The Time History Variables window should now look like this:

2. Graph Results over Time

Click on UY_2 in the Time History Variables window.

Click the graphing button in the Time History Variables window.



The labels on the plot are not updated by ANSYS, so you must change them manually. Select Utility Menu > Plot Ctrls > Style > Graphs > Modify Axes and re-label the X and Y-axis appropriately.

The plot shows how the beam became unstable and buckled with a load of approximately 40,000 N,the point where a large deflection occured due to a small increase in force. This is slightly less than the eigen-value solution of 41,123 N, which was expected due to non-linear geometry issues discussed above.





NonLinear Materials

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to describe how to include material nonlinearities in an ANSYS model. For instance, the case when a large force is applied resulting in a stresses greater than yield strength. In such a case, a multilinear stress-strain relationship can be included which follows the stress-strain curve of the material being used. This will allow ANSYS to more accurately model the plastic deformation of the material.

For this analysis, a simple tension speciment 100 mm X 5 mm X 5 mm is constrained at the bottom and has a load pulling on the top. This specimen is made out of a experimental substance called "WhoKilledKenium". The stress-strain curve for the substance is shown above. Note the linear section up to approximately 225 MPa where the Young's Modulus is constant (75 GPa). The material then begins to yield and the relationship becomes plastic and nonlinear.


Utility Menu > File > Change Title ... /title, NonLinear Materials

2. Create Keypoints Preprocessor > Modeling > Create > Keypoints > In Active CS /PREP7 K,#,X,Y

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/NonLinearMat/NonLine...


We are going to define 2 keypoints (the beam vertices) for this structure to create a beam with a length of 100 millimeters:


Create a line between Keypoint 1 and Keypoint 2. L,1,2


For this problem we will use the LINK1 (2D spar) element. This element has 2 degrees of freedom (translation along the X and Y axis's) and can only be used in 2D analysis.


In the 'Real Constants for LINK1' window, enter the following geometric properties: i. Cross-sectional area AREA: 25

ii. Initial Strain: 0

This defines an element with a solid rectangular cross section 5 x 5 millimeters.




Now that the initial properties of the material have been outlined, the stress-strain data must be included.

Preprocessor > Material Props > Material Models > Structural > Nonlinear > Elastic > Multilinear Elastic The following window will pop up.




Fill in the STRAIN and STRESS boxes with the following data. These are points from the stress-strain curve shown above, approximating the curve with linear interpolation between the points. When the data for the first point is input, click Add Point to add another. When all the points have been inputed, click Graph to see the curve. It should look like the one shown above. Then click OK.

To get the problem geometry back, select Utility Menu > Plot > Replot. /REPLOT

7. Define Mesh Size Preprocessor > Meshing > Manual Size > Size Cntrls > Lines > All Lines...

Curve Points Strain Stress

1 0 02 0.001 753 0.002 1504 0.003 2255 0.004 2406 0.005 2507 0.025 3008 0.060 3559 0.100 39010 0.150 42011 0.200 43512 0.250 44913 0.275 450





Solution: Assigning Loads and Solving













F. Ensure all solution items are writen to a results file. This means rather than just recording the data for the last load step, data for every load step is written to the database. Therefore, you can plot certain parameters over time.


A. Ensure Line Search is 'On'. This option is used to help the Newton-Raphson solver converge.

B. Ensure Maximum Number of Iterations is set to 1000







Place a 10,000 N load in the FY direction on the top of the beam (Keypoint 2).


The following will appear on your screen for NonLinear Analyses



1. To view the element in 2D rather than a line: Utility Menu > PlotCtrls > Style > Size and Shape and turn 'Display of element' ON (as shown below).



2. View the deflection contour plot General Postproc > Plot Results > Contour Plot > Nodal Solu... > DOF solution, UY PLNSOL,U,Y,0,1





As shown, you can obtain the results (such as deflection, stress and bending moment diagrams) the same way you did in previous examples using the General Postprocessor. However, you may wish to view time history results such as the deflection of the object over time.

1. Define Variables






Select Nodal Solution > DOF Solution > Y-Component of displacement (as shown below) and click OK. Pick the uppermost node on the beam and click OK in the 'Node for Data' window.

To add another variable, click the add button again. This time select Reaction Forces > Structural Forces > Y-Component of Force. Pick the lowermost node on the beam and click OK.

On the Time History Variable window, click the circle in the 'X-Axis' column for FY_3. This will make the reaction force the x-variable. The Time History Variables window should now look like this:




Click on UY_2 in the Time History Variables window.





This plot shows how the beam deflected linearly when the force, and subsequently the stress, was low (in the linear range). However, as the force increased, the deflection (proportional to strain) began to increase at a greater rate. This is because the stress in the beam is in the plastic range and thus no longer relates to strain linearly. When you verify this example analytically, you will see the solutions are very similar. The difference can be attributed to the ANSYS solver including large deflection calculations.





Modal Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to outline the steps required to do a simple modal analysis of the cantilever beam shown below.

Preprocessing: Defining the Problem The simple cantilever beam is used in all of the Dynamic Analysis Tutorials. If you haven't created the model in ANSYS, please use the links below. Both the command line codes and the GUI commands are shown in the respective links.


Solution > Analysis Type > New Analysis > Modal ANTYPE,2

2. Set options for analysis type:

Select: Solution > Analysis Type > Analysis Options..

The following window will appear

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/Modal/Modal.html


As shown, select the Subspace method and enter 5 in the 'No. of modes to extract'

Check the box beside 'Expand mode shapes' and enter 5 in the 'No. of modes to expand'

Click 'OK'

Note that the default mode extraction method chosen is the Reduced Method. This is the fastest method as it reduces the system matrices to only consider the Master Degrees of Freedom (see below). The Subspace Method extracts modes for all DOF's. It is therefore more exact but, it also takes longer to compute (especially when the complex geometries).

The following window will then appear



For a better understanding of these options see the Commands manual.

For this problem, we will use the default options so click on OK.




Postprocessing: Viewing the Results 1. Verify extracted modes against theoretical predictions

Select: General Postproc > Results Summary...




The following table compares the mode frequencies in Hz predicted by theory and ANSYS.

Note: To obtain accurate higher mode frequencies, this mesh would have to be refined even more (i.e. instead of 10 elements, we would have to model the cantilever using 15 or more elements depending upon the highest mode frequency of interest).

2. View Mode Shapes

Select: General Postproc > Read Results > First Set

This selects the results for the first mode shape

Select General Postproc > Plot Results > Deformed shape . Select 'Def + undef edge'

The first mode shape will now appear in the graphics window.

To view the next mode shape, select General Postproc > Read Results > Next Set . As above choose General Postproc > Plot Results > Deformed shape . Select 'Def + undef edge'.

The first four mode shapes should look like the following:

Mode Theory ANSYS Percent Error

1 8.311 8.300 0.1

2 51.94 52.01 0.2

3 145.68 145.64 0.0

4 285.69 285.51 0.0

5 472.22 472.54 0.1



3. Animate Mode Shapes

Select Utility Menu (Menu at the top) > Plot Ctrls > Animate > Mode Shape


Keep the default setting and click 'OK' The animated mode shapes are shown below.



Mode 1

Mode 2

Mode 3



Mode 4

Using the Reduced Method for Modal Analysis This method employs the use of Master Degrees of Freedom. These are degrees of freedom that govern the dynamic characteristics of a structure. For example, the Master Degrees of Freedom for the bending modes of cantilever beam are



For this option, a detailed understanding of the dynamic behavior of a structure is required. However, going this route means a smaller (reduced) stiffness matrix, and thus faster calculations.

The steps for using this option are quite simple.

Instead of specifying the Subspace method, select the Reduced method and specify 5 modes for extraction.

Complete the window as shown below

Note:For this example both the number of modes and frequency range was specified. ANSYS then extracts the minimum number of modes between the two.

Select Solution > Master DOF > User Selected > Define

When prompted, select all nodes except the left most node (fixed).




Select UY as the 1st degree of freedom (shown above).

The same constraints are used as above.

The following table compares the mode frequencies in Hz predicted by theory and ANSYS (Reduced).

As you can see, the error does not change significantly. However, for more complex structures, larger errors would be expected using the reduced method.

Mode Theory ANSYS Percent Error

1 8.311 8.300 0.1

2 51.94 52.01 0.1

3 145.68 145.66 0.0

4 285.69 285.71 0.0

5 472.22 473.66 0.3



Harmonic Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to explain the steps required to perform Harmonic analysis the cantilever beam shown below.

We will now conduct a harmonic forced response test by applying a cyclic load (harmonic) at the end of the beam. The frequency of the load will be varied from 1 - 100 Hz. The figure below depicts the beam with the application of the load.

ANSYS provides 3 methods for conducting a harmonic analysis. These 3 methods are the Full , Reduced and Modal Superposition methods.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/Harmonic/Harmonic.html


This example demonstrates the Full method because it is simple and easy to use as compared to the other two methods. However, this method makes use of the full stiffness and mass matrices and thus is the slower and costlier option.


Solution: Assigning Loads and Solving 1. Define Analysis Type (Harmonic)

Solution > Analysis Type > New Analysis > Harmonic ANTYPE,3

2. Set options for analysis type:

Select: Solution > Analysis Type > Analysis Options..


As shown, select the Full Solution method, the Real + imaginary DOF printout format and do not use lumped mass approx.

Click 'OK'

The following window will appear. Use the default settings (shown below).




Select Solution > Define Loads > Apply > Structural > Displacement > On Nodes

The following window will appear once you select the node at x=0 (Note small changes in the window compared to the static examples):

Constrain all DOF as shown in the above window

4. Apply Loads:

Select Solution > Define Loads > Apply > Structural > Force/Moment > On Nodes

Select the node at x=1 (far right)

The following window will appear. Fill it in as shown to apply a load with a real value of 100 and an imaginary value of 0 in the positive 'y' direction



Note: By specifying a real and imaginary value of the load we are providing information on magnitude and phase of the load. In this case the magnitude of the load is 100 N and its phase is 0. Phase information is important when you have two or more cyclic loads being applied to the structure as these loads could be in or out of phase. For harmonic analysis, all loads applied to a structure must have the SAME FREQUENCY.

5. Set the frequency range

Select Solution > Load Step Opts > Time/Frequency > Freq and Substps...

As shown in the window below, specify a frequency range of 0 - 100Hz, 100 substeps and stepped b.c..

By doing this we will be subjecting the beam to loads at 1 Hz, 2 Hz, 3 Hz, ..... 100 Hz. We will specify a stepped boundary condition (KBC) as this will ensure that the same amplitude (100 N) will be applyed for each of the frequencies. The ramped option, on the other hand, would ramp up the amplitude where at 1 Hz the amplitude would be 1 N and at 100 Hz the amplitude would be 100 N.

You should now have the following in the ANSYS Graphics window




Postprocessing: Viewing the Results We want to observe the response at x=1 (where the load was applyed) as a function of frequency. We cannot do this with General PostProcessing (POST1), rather we must use TimeHist PostProcessing (POST26). POST26 is used to observe certain variables as a function of either time or frequency.

1. Open the TimeHist Processing (POST26) Menu

Select TimeHist Postpro from the ANSYS Main Menu.

2. Define Variables

In here we have to define variables that we want to see plotted. By default, Variable 1 is assigned either Time or Frequency. In our case it is assigned Frequency. We want to see the displacement UY at the node at x=1, which is node #2. (To get a list of nodes and their attributes, select Utility Menu > List > nodes).

Select TimeHist Postpro > Variable Viewer... and the following window should pop up.



Select Add (the green '+' sign in the upper left corner) from this window and the following window should appear

We are interested in the Nodal Solution > DOF Solution > Y-Component of displacement. Click OK.



Graphically select node 2 when prompted and click OK. The 'Time History Variables' window should now look as follows

3. List Stored Variables

In the 'Time History Variables' window click the 'List' button, 3 buttons to the left of 'Add'

The following window will appear listing the data:

4. Plot UY vs. frequency

In the 'Time History Variables' window click the 'Plot' button, 2 buttons to the left of 'Add'



The following graph should be plotted in the main ANSYS window.

Note that we get peaks at frequencies of approximately 8.3 and 51 Hz. This corresponds with the predicted frequencies of 8.311 and 51.94Hz.

To get a better view of the response, view the log scale of UY.

Select Utility Menu > PlotCtrls > Style > Graphs > Modify Axis




As marked by an 'A' in the above window, change the Y-axis scale to 'Logarithmic'

Select Utility Menu > Plot > Replot

You should now see the following



This is the response at node 2 for the cyclic load applied at this node from 0 - 100 Hz.

For ANSYS version lower than 7.0, the 'Variable Viewer' window is not available. Use the 'Define Variables' and 'Store Data' functions under TimeHist Postpro. See the help file for instructions.



Transient Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to show the steps involved to perform a simple transient analysis.

Transient dynamic analysis is a technique used to determine the dynamic response of a structure under a time-varying load.

The time frame for this type of analysis is such that inertia or damping effects of the structure are considered to be important. Cases where such effects play a major role are under step or impulse loading conditions, for example, where there is a sharp load change in a fraction of time.

If inertia effects are negligible for the loading conditions being considered, a static analysis may be used instead.

For our case, we will impact the end of the beam with an impulse force and view the response at the location of impact.

http://www.mece.ualberta.ca/tutorials/ansys/IT/Transient/Transient.html

Copyright 2003 - University of Alberta

Since an ideal impulse force excites all modes of a structure, the response of the beam should contain all mode frequencies. However, we cannot produce an ideal impulse force numerically. We have to apply a load over a discrete amount of time dt.

After the application of the load, we track the response of the beam at discrete time points for as long as we like (depending on what it is that we are looking for in the response).

The size of the time step is governed by the maximum mode frequency of the structure we wish to capture. The smaller the time step, the higher the mode frequency we will capture. The rule of thumb in ANSYS is

time_step = 1 / 20f

where f is the highest mode frequency we wish to capture. In other words, we must resolve our step size such that we will have 20 discrete points per period of the highest mode frequency.

It should be noted that a transient analysis is more involved than a static or harmonic analysis. It requires a good understanding of the dynamic behavior of a structure. Therefore, a modal analysis of the structure should be initially performed to provide information about the structure's dynamic behavior.

In ANSYS, transient dynamic analysis can be carried out using 3 methods.



The Full Method: This is the easiest method to use. All types of non-linearities are allowed. It is however very CPU intensive to go this route as full system matrices are used.

The Reduced Method: This method reduces the system matrices to only consider the Master Degrees of Freedom (MDOFs). Because of the reduced size of the matrices, the calculations are much quicker. However, this method handles only linear problems (such as our cantilever case).

The Mode Superposition Method: This method requires a preliminary modal analysis, as factored mode shapes are summed to calculate the structure's response. It is the quickest of the three methods, but it requires a good deal of understanding of the problem at hand.

We will use the Reduced Method for conducting our transient analysis. Usually one need not go further than Reviewing the Reduced Results. However, if stresses and forces are of interest than, we would have to Expand the Reduced Solution.



Select Solution > Analysis Type > New Analysis > Transient

The following window will appear. Select 'Reduced' as shown.

2. Define Master DOFs

Select Solution > Master DOFs > User Selected > Define



Select all nodes except the left most node (at x=0).

The following window will open, choose UY as the first dof in this window

For an explanation on Master DOFs, see the section on Using the Reduced Method for modal analysis.

3. Constrain the Beam Solution Menu > Define Loads > Apply > Structural > Displacement > On nodes

Fix the left most node (constrain all DOFs).

4. Apply Loads

We will define our impulse load using Load Steps. The following time history curve shows our load steps and time steps. Note that for the reduced method, a constant time step is required throughout the time range.

We can define each load step (load and time at the end of load segment) and save them in a file for future solution purposes. This is highly recommended especially when we have many load steps and we wish to re-run our solution.

We can also solve for each load step after we define it. We will go ahead and save each load step



in a file for later use, at the same time solve for each load step after we are done defining it.

a. Load Step 1 - Initial Conditions

i. Define Load Step

We need to establish initial conditions (the condition at Time = 0). Since the equations for a transient dynamic analysis are of second order, two sets of initial conditions are required; initial displacement and initial velocity. However, both default to zero. Therefore, for this example we can skip this step.

ii. Specify Time and Time Step Options

Select Solution > Load Step Opts > Time/Frequenc > Time - Time Step .. set a time of 0 for the end of the load step (as shown below). set [DELTIM] to 0.001. This will specify a time step size of 0.001 seconds to be used for this load step.

iii. Write Load Step File

Select Solution > Load Step Opts > Write LS File




Enter LSNUM = 1 as shown above and click 'OK'

The load step will be saved in a file jobname.s01

b. Load Step 2

i. Define Load Step

Select Solution > Define Loads > Apply > Structural > Force/Moment > On Nodes and select the right most node (at x=1). Enter a force in the FY direction of value -100 N.


Select Solution > Load Step Opts > Time/Frequenc > Time - Time Step .. and set a time of 0.001 for the end of the load step

iii. Write Load Step File Solution > Load Step Opts > Write LS File

Enter LSNUM = 2

c. Load Step 3

i. Define Load Step

Select Solution > Define Loads > Delete > Structural > Force/Moment > On Nodes and delete the load at x=1.


Select Solution > Load Step Opts > Time/Frequenc > Time - Time Step .. and set a time of 1 for the end of the load step

iii. Write Load Step File Solution > Load Step Opts > Write LS File

Enter LSNUM = 3



5. Solve the System

Select Solution > Solve > From LS Files

The following window will appear.

Complete the window as shown above to solve using LS files 1 to 3.

Postprocessing: Viewing the Results To view the response of node 2 (UY) with time we must use the TimeHist PostProcessor (POST26).

1. Define Variables

In here we have to define variables that we want to see plotted. By default, Variable 1 is assigned either Time or Frequency. In our case it is assigned Frequency. We want to see the displacement UY at the node at x=1, which is node #2. (To get a list of nodes and their attributes, select Utility Menu > List > nodes).

Select TimeHist Postpro > Variable Viewer... and the following window should pop up.



Select Add (the green '+' sign in the upper left corner) from this window and the following window should appear

We are interested in the Nodal Solution > DOF Solution > Y-Component of displacement. Click OK.



Graphically select node 2 when prompted and click OK. The 'Time History Variables' window should now look as follows

2. List Stored Variables

In the 'Time History Variables' window click the 'List' button, 3 buttons to the left of 'Add'

The following window will appear listing the data:

3. Plot UY vs. frequency

In the 'Time History Variables' window click the 'Plot' button, 2 buttons to the left of 'Add'



The following graph should be plotted in the main ANSYS window.

A few things to note in the response curve

There are approximately 8 cycles in one second. This is the first mode of the cantilever beam and we have been able to capture it.

We also see another response at a higher frequency. We may have captured some response at the second mode at 52 Hz of the beam.

Note that the response does not decay as it should not. We did not specify damping for our system.

Expand the Solution

For most problems, one need not go further than Reviewing the Reduced Results as the response of the structure is of utmost interest in transient dynamic analysis.

However, if stresses and forces are of interest, we would have to expand the reduced solution.

Let's say we are interested in the beam's behaviour at peak responses. We should then expand a few or all solutions around one peak (or dip). We will expand 10 solutions within the range of 0.08 and 0.11 seconds.

1. Expand the solution

Select Finish in the ANSYS Main Menu



Select Solution > Analysis Type > ExpansionPass... and switch it to ON in the window that pops open.

Select Solution > Load Step Opts > ExpansionPass > Single Expand > Range of Solu's

Complete the window as shown below. This will expand 10 solutions withing the range of 0.08 and 0.11 seconds


3. Review the results in POST1

Review the results using either General Postprocessing (POST1) or TimeHist Postprocessing (POST26). For this case, we can view the deformed shape at each of the 10 solutions we expanded.

Damped Response of the Cantilever Beam

We did not specify damping in our transient analysis of the beam. We specify damping at the same time we specify our time & time steps for each load step.

We will now re-run our transient analysis, but now we will consider damping. Here is where the use of load step files comes in handy. We can easily change a few values in these files and re-run our whole solution from these load case files.

Open up the first load step file (Dynamic.s01) for editing Utility Menu > File > List > Other > Dynamic.s01. The file should look like the following..

/COM,ANSYS RELEASE 5.7.1 UP20010418 14:44:02 08/20/2001 /NOPR /TITLE, Dynamic Analysis _LSNUM= 1



ANTYPE, 4 TRNOPT,REDU,,DAMP BFUNIF,TEMP,_TINY DELTIM, 1.000000000E-03 TIME, 0.00000000 TREF, 0.00000000 ALPHAD, 0.00000000 BETAD, 0.00000000 DMPRAT, 0.00000000 TINTP,R5.0, 5.000000000E-03,,, TINTP,R5.0, -1.00000000 , 0.500000000 , -1.00000000 NCNV, 1, 0.00000000 , 0, 0.00000000 , 0.00000000 ERESX,DEFA ACEL, 0.00000000 , 0.00000000 , 0.00000000 OMEGA, 0.00000000 , 0.00000000 , 0.00000000 , 0 DOMEGA, 0.00000000 , 0.00000000 , 0.00000000 CGLOC, 0.00000000 , 0.00000000 , 0.00000000 CGOMEGA, 0.00000000 , 0.00000000 , 0.00000000 DCGOMG, 0.00000000 , 0.00000000 , 0.00000000 D, 1,UX , 0.00000000 , 0.00000000 D, 1,UY , 0.00000000 , 0.00000000 D, 1,ROTZ, 0.00000000 , 0.00000000 /GOPR

Change the damping value BETAD from 0 to 0.01 in all three load step files.

We will have to re-run the job for the new load step files. Select Utility Menu > file > Clear and Start New.

Repeat the steps shown above up to the point where we select MDOFs. After selecting MDOFs, simply go to Solution > (-Solve-) From LS files ... and in the window that opens up select files from 1 to 3 in steps of 1.

After the results have been calculated, plot up the response at node 2 in POST26. The damped response should look like the following






Simple Conduction Example

Introduction This tutorial was created using ANSYS 7.0 to solve a simple conduction problem.

The Simple Conduction Example is constrained as shown in the following figure. Thermal conductivity (k) of the material is 10 W/m*C and the block is assumed to be infinitely long.


2. Create geometry Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners > X=0, Y=0, Width=1, Height=1 BLC4,0,0,1,1

3. Define the Type of Element Preprocessor > Element Type > Add/Edit/Delete... > click 'Add' > Select Thermal Solid, Quad 4Node 55 ET,1,PLANE55

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/Conduction/Conduction....


For this example, we will use PLANE55 (Thermal Solid, Quad 4node 55). This element has 4 nodes and a single DOF (temperature) at each node. PLANE55 can only be used for 2 dimensional steady-state or transient thermal analysis.

4. Element Material Properties Preprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic > KXX = 10 (Thermal conductivity) MP,KXX,1,10

5. Mesh Size Preprocessor > Meshing > Size Cntrls > ManualSize > Areas > All Areas > 0.05 AESIZE,ALL,0.05

6. Mesh Preprocessor > Meshing > Mesh > Areas > Free > Pick All AMESH,ALL


Solution > Analysis Type > New Analysis > Steady-State ANTYPE,0


For thermal problems, constraints can be in the form of Temperature, Heat Flow, Convection, Heat Flux, Heat Generation, or Radiation. In this example, all 4 sides of the block have fixed temperatures.

Solution > Define Loads > Apply Note that all of the -Structural- options cannot be selected. This is due to the type of element (PLANE55) selected.

Thermal > Temperature > On Nodes

Click the Box option (shown below) and draw a box around the nodes on the top line.




Fill the window in as shown to constrain the side to a constant temperature of 500

Using the same method, constrain the remaining 3 sides to a constant value of 100

Orange triangles in the graphics window indicate the temperature contraints.




Postprocessing: Viewing the Results 1. Results Using ANSYS

Plot Temperature General Postproc > Plot Results > Contour Plot > Nodal Solu ... > DOF solution, Temperature TEMP

Note that due to the manner in which the boundary contitions were applied, the top corners are held at a temperature of 100. Recall that the nodes on the top of the plate were constrained first, followed by the side and bottom constraints. The top corner nodes were therefore first constrained at 500C, then 'overwritten' when the side constraints were applied. Decreasing the mesh size can minimize this effect, however, one must be aware of the limitations in the results at the corners.




Thermal - Mixed Boundary Example (Conduction/Convection/Insulated)

Introduction This tutorial was created using ANSYS 7.0 to solve simple thermal examples. Analysis of a simple conduction as well a mixed conduction/convection/insulation problem will be demonstrated.

The Mixed Convection/Conduction/Insulated Boundary Conditions Example is constrained as shown in the following figure (Note that the section is assumed to be infinitely long):


2. Create geometry Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners > X=0, Y=0, Width=1, Height=1 BLC4,0,0,1,1

3. Define the Type of Element Preprocessor > Element Type > Add/Edit/Delete... > click 'Add' > Select Thermal Solid, Quad 4Node 55 ET,1,PLANE55

http://www.mece.ualberta.ca/tutorials/ansys/it/convection/convection.html


As in the conduction example, we will use PLANE55 (Thermal Solid, Quad 4node 55). This element has 4 nodes and a single DOF (temperature) at each node. PLANE55 can only be used for 2 dimensional steady-state or transient thermal analysis.

4. Element Material Properties Preprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic > KXX = 10 MP,KXX,1,10

This will specify a thermal conductivity of 10 W/m*C.




Solution > Analysis Type > New Analysis > Steady-State ANTYPE,0

2. Apply Conduction Constraints

In this example, all 2 sides of the block have fixed temperatures, while convection occurs on the other 2 sides.

Solution > Define Loads > Apply > Thermal > Temperature > On Lines

Select the top line of the block and constrain it to a constant value of 500 C

Using the same method, constrain the left side of the block to a constant value of 100 C

3. Apply Convection Boundary Conditions

Solution > Define Loads > Apply > Thermal > Convection > On Lines

Select the right side of the block.




Fill in the window as shown. This will specify a convection of 10 W/m2*C and an ambient temperature of 100 degrees Celcius. Note that VALJ and VAL2J have been left blank. This is because we have uniform convection across the line.

4. Apply Insulated Boundary Conditions

Solution > Define Loads > Apply > Thermal > Convection > On Lines

Select the bottom of the block.

Enter a constant Film coefficient (VALI) of 0. This will eliminate convection through the side, thereby modeling an insulated wall. Note: you do not need to enter a Bulk (or ambient) temperature






Plot Temperature General Postproc > Plot Results > Contour Plot > Nodal Solu ... > DOF solution, Temperature TEMP






Transient Thermal Conduction Example

Introduction This tutorial was created using ANSYS 7.0 to solve a simple transient conduction problem. Special thanks to Jesse Arnold for the analytical solution shown at the end of the tutorial.

The example is constrained as shown in the following figure. Thermal conductivity (k) of the material is 5 W/m*K and the block is assumed to be infinitely long. Also, the density of the material is 920 kg/m^3 and the specific heat capacity (c) is 2.040 kJ/kg*K.

It is beneficial if the Thermal-Conduction tutorial is completed first to compare with this solution.


Utility Menu > File > Change Title... /Title,Transient Thermal Conduction


University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/TransCond/Print.html


3. Create geometry Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners X=0, Y=0, Width=1, Height=1 BLC4,0,0,1,1

4. Define the Type of Element Preprocessor > Element Type > Add/Edit/Delete... > click 'Add' > Select Thermal Mass Solid, Quad 4Node 55 ET,1,PLANE55


5. Element Material Properties Preprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic > KXX = 5(Thermal conductivity) MP,KXX,1,10 Preprocessor > Material Props > Material Models > Thermal > Specific Heat > C = 2.04 MP,C,1,2.04 Preprocessor > Material Props > Material Models > Thermal > Density > DENS = 920 MP,DENS,1,920



At this point, the model should look like the following:




Solution > Analysis Type > New Analysis > Transient ANTYPE,4

The window shown below will pop up. We will use the defaults, so click OK.




Solution > Analysis Type > Sol'n Controls

The following window will pop up.

A) Set Time at end of loadstep to 300 and Automatic time stepping to ON. B) Set Number of substeps to 20, Max no. of substeps to 100, Min no. of substeps to 20. C) Set the Frequency to Write every substep.

Click on the NonLinear tab at the top and fill it in as shown



D) Set Line search to ON . E) Set the Maximum number of iterations to 100.

For a complete description of what these options do, refer to the help file. Basically, the time at the end of the load step is how long the transient analysis will run and the number of substeps defines how the load is broken up. By writing the data at every step, you can create animations over time and the other options help the problem converge quickly.


For thermal problems, constraints can be in the form of Temperature, Heat Flow, Convection, Heat Flux, Heat Generation, or Radiation. In this example, 2 sides of the block have fixed temperatures and the other two are insulated.

Solution > Define Loads > Apply Note that all of the -Structural- options cannot be selected. This is due to the type of element (PLANE55) selected.

Thermal > Temperature > On Nodes

Click the Box option (shown below) and draw a box around the nodes on the top line and then click OK.




Fill the window in as shown to constrain the top to a constant temperature of 500 K

Using the same method, constrain the bottom line to a constant value of 100 K

Orange triangles in the graphics window indicate the temperature contraints.

4. Apply Initial Conditions Solution > Define Loads > Apply > Initial Condit'n > Define > Pick All

Fill in the IC window as follows to set the initial temperature of the material to 100 K:



Plot Temperature General Postproc > Plot Results > Contour Plot > Nodal Solu ... > DOF solution, Temperature



TEMP

Animate Results Over Time

First, specify the contour range. Utility Menu > PlotCtrls > Style > Contours > Uniform Contours...

Fill in the window as shown, with 8 contours, user specified, from 100 to 500.



Then animate the data. Utility Menu > PlotCtrls > Animate > Over Time...

Fill in the following window as shown (20 frames, 0 - 300 Time Range, Auto contour scaling OFF, DOF solution > TEMP)



You can see how the temperature rises over the area over time. The heat flows from the higher temperature to the lower temperature constraints as expected. Also, you can see how it reaches equilibrium when the time reaches approximately 200 seconds. Shown below are analytical and ANSYS generated temperature vs time curves for the center of the block. As can be seen, the curves are practically identical, thus the validity of the ANSYS simulation has been proven.

Analytical Solution



ANSYS Generated Solution


1. Creating the Temperature vs. Time Graph






Select Nodal Solution > DOF Solution > Temperature (as shown below) and click OK. Pick the center node on the mesh, node 261, and click OK in the 'Node for Data' window.

The Time History Variables window should now look like this:




Ensure TEMP_2 in the Time History Variables window is highlighted.





Note how this plot does not exactly match the plot shown above. This is because the solution has not completely converged. To cause the solution to converge, one of two things can be done: decrease the mesh size or increase the number of substeps used in the transient analysis. From experience, reducing the mesh size will do little in this case, as the mesh is adequate to capture the response. Instead, increasing the number of substeps from say 20 to 300, will cause the solution to converge. This will greatly increase the computational time required though, which is why only 20 substeps are used in this tutorial. Twenty substeps gives an adequate and quick approximation of the solution.

Command File Mode of Solution The above example was solved using a mixture of the Graphical User Interface (or GUI) and the command language interface of ANSYS. This problem has also been solved using the ANSYS command language interface that you may want to browse. Open the .HTML version, copy and paste the code into Notepad or a similar text editor and save it to your computer. Now go to 'File > Read input from...' and select the file. A .PDF version is also available for printing.



Modelling Using Axisymmetry

Introduction This tutorial was completed using ANSYS 7.0 This tutorial is intended to outline the steps required to create an axisymmetric model.

The model will be that of a closed tube made from steel. Point loads will be applied at the center of the top and bottom plate to make an analytical verification simple to calculate. A 3/4 cross section view of the tube is shown below.

As a warning, point loads will create discontinuities in the your model near the point of application. If you chose to use these types of loads in your own modelling, be very careful and be sure to understand the theory of how the FEA package is appling the load and the assumption it is making. In this case, we will only be concerned about the stress distribution far from the point of application, so the discontinuities will have a negligable effect.


Utility Menu > File > Change Title ... /title, Axisymmetric Tube

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/IT/Axisymmetric/Print.html



3. Create Areas Preprocessor > Modeling > Create > Areas > Rectangle > By Dimensions RECTNG,X1,X2,Y1,Y2

For an axisymmetric problem, ANSYS will rotate the area around the y-axis at x=0. Therefore, to create the geometry mentioned above, we must define a U-shape.

We are going to define 3 overlapping rectangles as defined in the following table:

4. Add Areas Together Preprocessor > Modeling > Operate > Booleans > Add > Areas AADD,ALL

Click the Pick All button to create a single area.


For this problem we will use the PLANE2 (Structural, Solid, Triangle 6node) element. This element has 2 degrees of freedom (translation along the X and Y axes).

Many elements support axisymmetry, however if the Ansys Elements Reference (which can be found in the help file) does not discuss axisymmetric applications for a particular element type, axisymmetry is not supported.

6. Turn on Axisymmetry While the Element Types window is still open, click the Options... button.

Under Element behavior K3 select Axisymmetric.

Rectangle X1 X2 Y1 Y21 0 20 0 52 15 20 0 1003 0 20 95 100






8. Define Mesh Size Preprocessor > Meshing > Size Cntrls > ManualSize > Areas > All Areas


9. Mesh the frame Preprocessor > Meshing > Mesh > Areas > Free > click 'Pick All'

Your model should know look like this:





2. Apply Constraints Solution > Define Loads > Apply > Structural > Displacement > Symmetry B.C. > On Lines

Pick the two edges on the left, at x=0, as shown below. By using the symmetry B.C. command, ANSYS automatically calculates which DOF's should be constrained for the line of symmetry. Since the element we are using only has 2 DOF's per node, we could have constrained the lines in the x-direction to create the symmetric boundary conditions.

Utility Menu > Select > Entities

Select Nodes and By Location from the scroll down menus. Click Y coordinates and type 50 into the input box as shown below, then click OK.



Solution > Define Loads > Apply > Structural > Displacement > On Nodes > Pick All

Constrain the nodes in the y-direction (UY). This is required to constrain the model in space, otherwise it would be free to float up or down. The location to constrain the model in the y-direction (y=50) was chosen because it is along a symmetry plane. Therefore, these nodes won't move in the y-direction according to theory.

3. Utility Menu > Select > Entities

In the select entities window, click Sele All to reselect all nodes. It is important to always reselect all entities once you've finished to ensure future commands are applied to the whole model and not just a few entities. Once you've clicked Sele All, click on Cancel to close the window.

4. Apply Loads Solution > Define Loads > Apply > Structural > Force/Moment > On Keypoints Pick the top left corner of the area and click OK. Apply a load of 100 in the FY direction.

Solution > Define Loads > Apply > Structural > Force/Moment > On Keypoints Pick the bottom left corner of the area and click OK. Apply a load of -100 in the FY direction.







The stress across the thickness at y = 50mm is 0.182 MPa.

2. Determine the Stress Through the Thickness of the Tube Utility Menu > Select > Entities...

Select Nodes > By Location > Y coordinates and type 45,55 in the Min,Max box, as shown below



and click OK.

General Postproc > List Results > Nodal Solution > Stress > Components SCOMP

The following list should pop up.

If you take the average of the stress in the y-direction over the thickness of the tube, (0.18552 + 0.17866)/2, the stress in the tube is 0.182 MPa, matching the analytical solution. The average is used because in the analytical case, it is assumed the stress is evenly distributed across the thickness. This is only true when the location is far from any stress concentrators, such as corners. Thus, to approximate the analytical solution, we must average the stress over the thickness.



3. Plotting the Elements as Axisymmetric Utility Menu > PlotCtrls > Style > Symmetry Expansion > 2-D Axi-symmetric...

The following window will appear. By clicking on 3/4 expansion you can produce the figure shown at the beginning of this tutorial.

4. Extra Exercise

It is educational to repeat this tutorial, but leave out the key option which enables axisymmetric modelling. The rest of the commands remain the same. If this is done, the model is a flat, rectangular plate, with a rectangular hole in the middle. Both the stress distribution and deformed shape change drastically, as expected due to the change in geometry. Thus, when using axisymmetry be sure to verify the solutions you get are reasonable to ensure the model is infact axisymmetric.




Application of Joints and Springs in ANSYS

Introduction This tutorial was created using ANSYS 5.7.1. This tutorial will introduce:

the use of multiple elements in ANSYS elements COMBIN7 (Joints) and COMBIN14 (Springs) obtaining/storing scalar information and store them as parameters.

A 1000N vertical load will be applied to a catapult as shown in the figure below. The catapult is built from steel tubing with an outer diameter of 40 mm, a wall thickness of 10, and a modulus of elasticity of 200GPa. The springs have a stiffness of 5 N/mm.

Preprocessing: Defining the Problem 1. Open preprocessor menu

/PREP7

2. Give example a Title Utility Menu > File > Change Title ... /title,Catapult

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/Joints/Joints.html


3. Define Element Types

For this problem, 3 types of elements are used: PIPE16, COMBIN7 (Revolute Joint), COMBIN14 (Spring-Damper) . It is therefore required that the types of elements are defined prior to creating the elements. This element has 6 degrees of freedom (translation along the X, Y and Z axis, and rotation about the X,Y and Z axis).

a. Define PIPE16 With 6 degrees of freedom, the PIPE16 element can be used to create the 3D structure.

Preprocessor > Element Type > Add/Edit/Delete... > click 'Add' Select 'Pipe', 'Elast straight 16' Click on 'Apply' You should see 'Type 1 PIPE16' in the 'Element Types' window.

b. Define COMBIN7 COMBIN7 (Revolute Joint) will allow the catapult to rotate about nodes 1 and 2.

Select 'Combination', 'Revolute Joint 7' Click 'Apply'.

c. Define COMBIN14 Now we will define the spring elements.

Select 'Combination', 'Spring damper 14' Click on 'OK'

In the 'Element Types' window, there should now be three types of elements defined.

4. Define Real Constants

Real Constants must be defined for each of the 3 element types.

a. PIPE16 Preprocessor > Real Constants > Add/Edit/Delete... > click 'Add' Select Type 1 PIPE16 and click 'OK' Enter the following properties, then click 'OK'

OD = 40 TKWALL = 10

'Set 1' will now appear in the dialog box

b. COMBIN7 (Joint)

Five of the degrees of freedom (UX, UY, UZ, ROTX, and ROTY) can be constrained with different levels of flexibility. These can be defined by the 3 real constants: K1 (UX, UY), K2 (UZ) and K3 (ROTX, ROTY). For this example, we will use high values for K1 through K3 since we only expect the model to rotate about the Z axis.

Click 'Add' Select 'Type 2 COMBIN7'. Click 'OK'. In the 'Real Constants for COMBIN7' window, enter the following geometric properties (then click 'OK'):

X-Y transnational stiffness K1: 1e9 Z directional stiffness K2: 1e9



Rotational stiffness K3: 1e9 'Set 2' will now appear in the dialog box.

Note: The constants that we define in this problem refer to the relationship between the coincident nodes. By having high values for the stiffness in the X-Y plane and along the Z axis, we are essentially constraining the two coincident nodes to each other.

c. COMBIN14 (Spring) Click 'Add' Select 'Type 3 COMBIN14'. Click 'OK'. Enter the following geometric properties:

Spring constant K: 5

In the 'Element Types' window, there should now be three types of elements defined.

5. Define Element Material Properties 1. Preprocessor > Material Props > Material Models 2. In the 'Define Material Model Behavior' Window, ensure that Material Model Number 1 is selected 3. Select Structural > Linear > Elastic > Isotropic 4. In the window that appears, enter the give the properties of Steel then click 'OK'.

Young's modulus EX: 200000 Poisson's Ratio PRXY: 0.33

6. Define Nodes Preprocessor > (-Modeling-) Create > Nodes > In Active CS... N,#,x,y,z

We are going to define 13 Nodes for this structure as given in the following table (as depicted by the circled numbers in the figure above):

Node Coordinates (x,y,z)

1 (0,0,0)

2 (0,0,1000)

3 (1000,0,1000)

4 (1000,0,0)

5 (0,1000,1000)

6 (0,1000,0)

7 (700,700,500)

8 (400,400,500)

9 (0,0,0)

10 (0,0,1000)

11 (0,0,500)

12 (0,0,1500)



7. Create PIPE16 elements

a. Define element type Preprocessor > (-Modeling-) Create > Elements > Elem Attributes ...

The following window will appear. Ensure that the 'Element type number' is set to 1 PIPE16, 'Material number' is set to 1, and 'Real constant set number' is set to 1. Then click 'OK'.

b. Create elements Preprocessor > (-Modeling-) Create > Elements > (-Auto Numbered-) Thru Nodes E, node a, node b

Create the following elements joining Nodes 'a' and Nodes 'b'. Note: because it is difficult to graphically select the nodes you may wish to use the command line (for example, the first entry would be: E,1,6).

13 (0,0,-500)

Node a Node b1 62 51 42 33 4

10 89 87 8

12 5



You should obtain the following geometry (Oblique view)

8. Create COMBIN7 (Joint) elements

a. Define element type Preprocessor > (-Modeling-) Create > Elements > Elem Attributes Ensure that the 'Element type number' is set to 2 COMBIN7 and that 'Real constant set number' is set to 2. Then click 'OK'

b. Create elements When defining a joint, three nodes are required. Two nodes are coincident at the point of rotation. The elements that connect to the joint must reference each of the coincident points. The other node for the joint defines the axis of rotation. The axis would be the line from the coincident nodes to the other node.

Preprocessor > (-Modeling-) Create > Elements > (-Auto Numbered-) Thru Nodes E,node a, node b, node c

Create the following lines joining Node 'a' and Node 'b'

9. Create COMBIN14 (Spring) elements

13 612 135 36 4

Node a Node b Node c1 9 112 10 11



a. Define element type Preprocessor > (-Modeling-) Create > Elements > Elem Attributes Ensure that the 'Element type number' is set to 3 COMBIN7 and that 'Real constant set number' is set to 3. Then click 'OK'

b. Create elements Preprocessor > (-Modeling-) Create > Elements > (-Auto Numbered-) Thru Nodes E,node a, node b

Create the following lines joining Node 'a' and Node 'b'

NOTE: To ensure that the correct nodes were used to make the correct element in the above table, you can list all the elements defined in the model. To do this, select Utilities Menu > List > Elements > Nodes + Attributes.

10. Meshing

Because we have defined our model using nodes and elements, we do not need to mesh our model. If we initially defined our model using keypoints and lines, we would have had to create elements in our model by meshing the lines. It is the elements that ANSYS uses to solve the model.

11. Plot Elements Utility Menu > Plot > Elements

You may also wish to turn on element numbering and turn off keypoint numbering Utility Menu > PlotCtrls > Numbering ...

Node a Node b5 88 6





2. Allow Large Deflection Solution > Sol'n Controls > basic NLGEOM, ON

Because the model is expected to deform considerably, we need to include the effects of large deformation.

3. Apply Constraints Solution > (-Loads-) Apply > (-Structural-) > Displacement > On Nodes

Fix Nodes 3, 4, 12, and 13. (ie - all degrees of freedom are constrained).

4. Apply Loads Solution > (-Loads-) Apply > (-Structural-) > Force/Moment > On Nodes

Apply a vertical point load of 1000N at node #7.


Note: To have the constraints and loads appear each time you select 'Replot' in ANSYS, you must change some settings under Utility Menu > Plot Ctrls > Symbols.... In the window that appears check the box beside 'All Applied BC's' in the 'Boundary Condition Symbol' section.



5. Solve the System Solution > (-Solve-) Current LS SOLVE

Note: During the solution, you will see a yellow warning window which states that the "Coefficient ratio exceeds 1.0e8". This warning indicates that the solution has relatively large displacements. This is due to the rotation about the joints.

Postprocessing: Viewing the Results 1. Plot Deformed Shape

General Postproc > Plot Results > Deformed Shape PLDISP.2

2. Extracting Information as Parameters

In this problem, we would like to find the vertical displacement of node #7. We will do this using the GET command.

a. Select Utility Menu > Parameters > Get Scalar Data...

b. The following window will appear. Select 'Results data' and 'Nodal results' as shown then click 'OK'



c. Fill in the 'Get Nodal Results Data' window as shown below:

d. To view the defined parameter select Utility Menu > Parameters > Scalar Parameters...



Therefore the vertical displacement of Node 7 is 323.78 mm. This can be repeated for any of the other nodes you are interested in.




Design Optimization

Introduction This tutorial was completed using ANSYS 7.0 The purpose of this tutorial is to introduce a method of solving design optimization problems using ANSYS. This will involve creating the geometry utilizing parameters for all the variables, deciding which variables to use as design, state and objective variables and setting the correct tolerances for the problem to obtain an accurately converged solution in a minimal amount of time. The use of hardpoints to apply forces/constraints in the middle of lines will also be covered in this tutorial.

A beam has a force of 1000N applied as shown below. The purpose of this optimization problem is to minimize the weight of the beam without exceeding the allowable stress. It is necessary to find the cross sectional dimensions of the beam in order to minimize the weight of the beam. However, the width and height of the beam cannot be smaller than 10mm. The maximum stress anywhere in the beam cannot exceed 200 MPa. The beam is to be made of steel with a modulus of elasticity of 200 GPa.


Utility Menu > File > Change Title ... /title, Design Optimization

2. Enter initial estimates for variables

To solve an optimization problem in ANSYS, parameters need to be defined for all design variables.

Select: Utility Menu > Parameters > Scalar Parameters... In the window that appears (shown below), type W=20 in the ‘Selection’ section

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/Optimization/Optimizati...


Click ‘Accept’. The 'Scalar Parameters' window will stay open. Now type H=20 in the ‘Selection’ section Click ‘Accept' Click ‘Close’ in the ‘Scalar Parameters’ window.

NOTE: None of the variables defined in ANSYS are allowed to have negative values.

3. Define Keypoints Preprocessor > Modeling > Create > Keypoints > In Active CS... K,#,x,y

We are going to define 2 Keypoints for this beam as given in the following table:

4. Create Lines Preprocessor > Modeling > Create > Lines > Lines > In Active Coord L,1,2


5. Create Hard Keypoints

Hardpoints are often used when you need to apply a constraint or load at a location where a keypoint does not exist. For this case, we want to apply a force 3/4 of the way down the beam. Since there are not any keypoints here and we can't be certain that one of the nodes will be here we will need to specify a hardpoint

Select Preprocessor > Modeling > Create > Keypoints > Hard PT on line > Hard PT by ratio. This will allow us to create a hardpoint on the line by defining the ratio of the location of the point

Keypoints Coordinates (x,y)1 (0,0)2 (1000,0)



to the size of the line

Select the line when prompted

Enter a ratio of 0.75 in the 'Create HardPT by Ratio window which appears.

You have now created a keypoint labelled 'Keypoint 3' 3/4 of the way down the beam.




In the 'Real Constants for BEAM3' window, enter the following geometric properties: (Note that '**' is used instead '^' for exponents)

i. Cross-sectional area AREA: W*H ii. Area moment of inertia IZZ: (W*H**3)/12

iii. Thickness along Y axis: H

NOTE: It is important to use independent variables to define dependent variables such as the moment of inertia. During the optimization, the width and height will change for each iteration. As a result, the other variables must be defined in relation to the width and height.












Pin Keypoint 1 (ie UX, UY constrained) and constrain Keypoint 2 in the Y direction.


Apply a vertical (FY) point load of -2000N at Keypoint 3




Extracting Information as Parameters:

To perform an optimization, we must extract the required information.

In this problem, we would like to find the maximum stress in the beam and the volume as a result of the width and height variables.



1. Define the volume

Select General Postproc > Element Table > Define Table... > Add...

The following window will appear. Fill it in as shown to obtain the volume of the beam.

Note that this is the volume of each element. If you were to list the element table you would get a volume for each element. Therefore, you have to sum the element values together to obtain the total volume of the beam. Follow the instructions below to do this.

Select General Postproc > Element Table > Sum of Each Item...

A little window will appear notifying you that the tabular sum of each element table will be calculated. Click 'OK'

You will obtain a window notifying you that the EVolume is now 400000 mm2

2. Store the data (Volume) as a parameter

Select Utility Menu > Parameters > Get Scalar Data...

In the window which appears select 'Results Data' and 'Elem table sums'

the following window will appear. Select the items shown to store the Volume as a parameter.



Now if you view the parameters (Utility Menu > Parameters > Scalar Parameters...) you will see that Volume has been added.

3. Define the maximum stress at the i node of each element in the beam


The following window will appear. Fill it in as shown to obtain the maximum stress at the i node of each element and store it as 'SMAX_I'.

Note that nmisc,1 is the maximum stress. For further information type Help beam3 into the command line

Now we will need to sort the stresses in descending order to find the maximum stress

Select General Postproc > List Results > Sorted Listing > Sort Elems

Complete the window as shown below to sort the data from 'SMAX_I' in descending order



4. Store the data (Max Stress) as a parameter


In the window which appears select 'Results Data' and 'Other operations'

In the that appears, fill it in as shown to obtain the maximum value.

5. Define maximum stress at the j node of each element for the beam


Fill this table as done previously, however make the following changes: save the data as 'SMAX_J' (instead of 'SMAX_I') The element table data enter NMISC,3 (instead of NMISC,1). This will give you the max stress at the j node.

Select General Postproc > List Results > Sorted Listing > Sort Elems to sort the stresses in descending order.

However, select 'SMAX_J' in the Item, Comp selection box

6. Store the data (Max Stress) as a parameter




In the window which appears select 'Results Data' and 'Other operations'

In the that appears, fill it in as shown previously , however, name the parameter 'SMaxJ'.

7. Select the largest of SMAXJ and SMAXI Type SMAX=SMAXI>SMAXJ into the command line

This will set the largest of the 2 values equal to SMAX. In this case the maximum values for each are the same. However, this is not always the case.

8. View the parametric data Utility Menu > Parameters > Scalar Parameters

Note that the maximum stress is 281.25 which is much larger than the allowable stress of 200MPa

Design Optimization

Now that we have parametrically set up our problem in ANSYS based on our initial width and height dimensions, we can now solve the optimization problem.

1. Write the command file

It is necessary to write the outline of our problem to an ANSYS command file. This is so that ANSYS can iteratively run solutions to our problem based on different values for the variables that we will define.

Select Utility Menu > File > Write DB Log File... In the window that appears type a name for the command file such as ‘optimize.txt’ Click ‘OK’.

If you open the command file in a text editor such as Notepad, it should similar to this:

/BATCH ! /COM,ANSYS RELEASE 7.0 UP20021010 16:10:03 05/26/2003 /input,start70,ans,'C:\Program Files\Ansys Inc\v70\ANSYS\apdl\',,,,,,,,,,,,,,,,1 /title, Design Optimization *SET,W , 20 *SET,H , 20 /PREP7 K,1,0,0,, K,2,1000,0,, L, 1, 2 !* HPTCREATE,LINE,1,0,RATI,0.75, !* ET,1,BEAM3 !* !* R,1,W*H,(W*H**3)/12,H, , , , !* !* MPTEMP,,,,,,,,



MPTEMP,1,0 MPDATA,EX,1,,200000 MPDATA,PRXY,1,,.3 !* LESIZE,ALL,100, , , ,1, , ,1, LMESH, 1 FINISH /SOL !* ANTYPE,0 FLST,2,1,3,ORDE,1 FITEM,2,1 !* /GO DK,P51X, , , ,0,UX,UY, , , , , FLST,2,1,3,ORDE,1 FITEM,2,2 !* /GO DK,P51X, , , ,0,UY, , , , , , FLST,2,1,3,ORDE,1 FITEM,2,3 !* /GO FK,P51X,FY,-2000 ! /STATUS,SOLU SOLVE FINISH /POST1 AVPRIN,0,0, ETABLE,EVolume,VOLU, !* SSUM !* *GET,Volume,SSUM, ,ITEM,EVOLUME AVPRIN,0,0, ETABLE,SMax_I,NMISC, 1 !* ESORT,ETAB,SMAX_I,0,1, , !* *GET,SMaxI,SORT,,MAX AVPRIN,0,0, ETABLE,SMax_J,NMISC, 3 !* ESORT,ETAB,SMAX_J,0,1, , !* *GET,SMaxJ,SORT,,MAX *SET,SMAX,SMAXI>SMAXJ ! LGWRITE,optimization,,C:\Temp\,COMMENT

Several small changes need to be made to this file prior to commencing the optimization. If you created the geometry etc. using command line code, most of these changes will already be made. However, if you used GUI to create this file there are several occasions where you used the graphical picking device. Therefore, the actual items that were chosen need to be entered. The code 'P51X' symbolizes the graphical selection. To modify the file simply open it using notepad and make the required changes. Save and close the file once you have made all of the required changes. The following is a list of the changes which need to be made to this file (which was created using the GUI method)



Line 32 - DK,P51X, ,0, ,0,UX,UY, , , , , Change this to: DK,1, ,0, ,0,UX,UY, This specifies the constraints at keypoint 1

Line 37 - DK,P51X, ,0, ,0,UY, , , , , , Change to: DK,2, ,0, ,0,UY, This specifies the constraints at keypoint 2

Line 42 - FK,P51X,FY,-2000 Change to: FK,3,FY,-2000 This specifies the force applied on the beam

There are also several lines which can be removed from this file. If you are comfortable with command line coding, you should remove the lines which you are certain are not required.

2. Assign the Command File to the Optimization Select Main Menu > Design Opt > Analysis File > Assign In the file list that appears, select the filename that you created when you wrote the command file. Click ‘OK’.

3. Define Variables and Tolerances

ANSYS needs to know which variables are critical to the optimization. To define variables, we need to know which variables have an effect on the variable to be minimized. In this example our objective is to minimize the volume of a beam which is directly related to the weight of the beam.

ANSYS categorizes three types of variables for design optimization:

Design Variables (DVs) Independent variables that directly effect the design objective. In this example, the width and height of the beam are the DVs. Changing either variable has a direct effect on the solution of the problem.

State Variables (SVs) Dependent variables that change as a result of changing the DVs. These variables are necessary to constrain the design. In this example, the SV is the maximum stress in the beam. Without this SV, our optimization will continue until both the width and height are zero. This would minimize the weight to zero which is not a useful result.

Objective Variable (OV) The objective variable is the one variable in the optimization that needs to be minimized. In our problem, we will be minimizing the volume of the beam.

NOTE: As previously stated, none of the variables defined in ANSYS are allowed to have negative values.

Now that we have decided our design variables, we need to define ranges and tolerances for each variable. For the width and height, we will select a range of 10 to 50 mm for each. Because a small change in either the width or height has a profound effect on the volume of the beam, we will select a tolerance of 0.01mm. Tolerances are necessary in that they tell ANSYS the largest amount of change that a variable can experience before convergence of the problem.



For the stress variable, we will select a range of 195 to 200 MPa with a tolerance of 0.01MPa.

Because the volume variable is the objective variable, we do not need to define an allowable range. We will set the tolerance to 200mm3. This tolerance was chosen because it is significantly smaller than the initial magnitude of the volume of 400000mm3 (20mm x 20mm x 1000mm).

a. Define the Design Variables (width and height of beam)

Select Main Menu > Design Opt > Design Variables... > Add...

Complete the window as shown below to specify the variable limits and tolerances for the height of the beam.

Repeat the above steps to specify the variable limits for the width of the beam (identical to specifications for height)

b. Define the State Variables

Select Main Menu > Design Opt > State Variables... > Add...

In the window fill in the following sections Select 'SMAX' in the ‘Parameter Name’ section. Enter: Lower Limit (MIN = 195) Upper Limit (MAX = 200) Feasibility Tolerance (TOLER = 0.001)

c. Define the Objective Variable

Select Main Menu > Design Opt > Objective...



Select ‘VOLUME’ in the ‘Parameter Name’ section. Under Convergence Tolerance, enter 200.

4. Define the Optimization Method

There are several different methods that ANSYS can use to solve an optimization problem. To ensure that you are not finding a solution at a local minimum, it is advisable to use different solution methods. If you have trouble with getting a particular problem to converge it would be a good idea to try a different method of solution to see what might be wrong.

For this problem we will use a First-Order Solution method.

Select Main Menu > Design Opt > Method / Tool... In the ‘Specify Optimization Method’ window select ‘First-Order’ Click ‘OK’ Enter: Maximum iterations (NITR = 30), Percent step size SIZE = 100, Percent forward diff. DELTA = 0.2 Click ‘OK’.

Note: the significance of the above variables is explained below: NITR

Max number of iterations. Defaults to 10. SIZE

% that is applied to the size of each line search step. Defaults to 100% DELTA

forward difference (%) applied to the design variable range that is used to compute the gradient. Defaults to 0.2%

5. Run the Optimization

Select Main Menu > Design Opt > Run... In the ‘Begin Execution of Run’ window, confirm that the analysis file, method/type and maximum iterations are correct. Click ‘OK’.

The solution of an optimization problem can take awhile before convergence. This problem will take about 15 minutes and run through 19 iterations.

View the Results

1. View Final Parameters Utility Menu > Parameters > Scalar Parameters...

You will probably see that the width=13.24 mm, height=29.16 mm, and the stress is equal to 199.83 MPa with a volume of 386100mm2.

2. View graphical results of each variable during the solution

Select Main Menu > Design Opt > Design Sets > Graphs / Tables...



Complete the window as shown to obtain a graph of the height and width of the beam changing with each iteration

A. For the ‘X-variable parameter’ select ‘Set number’. B. For the ‘Y-variable parameter’ select ‘H’ and ‘W’. C. Ensure that 'Graph' is selected (as opposed to 'List')

Now you may wish to specify titles for the X and Y axes

Select Utility Menu > Plot Ctrls > Style > Graphs > Modify Axes... In the window, enter ‘Number of Iterations’ for the ‘X-axis label’ section. Enter ‘Width and Height (mm)’ for the ‘Y-axis label’. Click 'OK' Select Utility Menu > PlotCtrls

In the graphics window, you will see a graph of width and height throughout the optimization. You can print the plot by selecting Utility Menu > PlotCtrls > Hard Copy...



You can plot graphs of the other variables in the design by following the above steps. Instead of using width and height for the y-axis label and variables, use whichever variable is necessary to plot. Alternatively, you could list the data by selecting Main Menu > Design Opt > Design Sets > List... . In addition, all of the results data (ie stress, displacement, bending moments) are available from the General Postproc menu.

Command File Mode of Solution The above example was solved using the Graphical User Interface (or GUI) of ANSYS. This problem has also been solved using the ANSYS command language interface that you may want to browse. Open the file and save it to your computer.

***IMPORTANT*** Before running this code, select Main Menu > Design Opt > Opt Database > Clear & Reset to clear the optimization database. Then select Utility Menu > File > Clear & Start New. Now go to 'File > Read input from...' and select the file.



Substructuring

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to show the how to use substructuring in ANSYS. Substructuring is a procedure that condenses a group of finite elements into one super-element. This reduces the required computation time and also allows the solution of very large problems.

A simple example will be demonstrated to explain the steps required, however, please note that this model is not one which requires the use of substructuring. The example involves a block of wood (E =10 GPa v =0.29) connected to a block of silicone (E = 2.5 MPa, v = 0.41) which is rigidly attached to the ground. A force will be applied to the structure as shown in the following figure. For this example, substructuring will be used for the wood block.

The use of substructuring in ANSYS is a three stage process:

1. Generation Pass Generate the super-element by condensing several elements together. Select the degrees of freedom to save (master DOFs) and to discard (slave DOFs). Apply loads to the super-element

2. Use Pass Create the full model including the super-element created in the generation pass. Apply remaining loads to the model. The solution will consist of the reduced solution tor the super-element and the complete solution for the non-superelements.

3. Expansion Pass Expand the reduced solution to obtain the solution at all DOFs for the super-element.

Note that a this method is a bottom-up substructuring (each super-element is created separately and then assembled in the Use Pass). Top-down substructuring is also possible in ANSYS (the entire model is built, then

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/Substructuring/Substruct...


super-element are created by selecting the appropriate elements). This method is suitable for smaller models and has the advantage that the results for multiple super-elements can be assembled in postprocessing.

Expansion Pass: Creating the Super-element


1. Give Generation Pass a Jobname Utility Menu > File > Change Jobname ...

Enter 'GEN' for the jobname


3. Create geometry of the super-element Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners BLC4,XCORNER,YCORNER,WIDTH,HEIGHT

Create a rectangle with the dimensions (all units in mm):

XCORNER (WP X) = 0 YCORNER (WP Y) = 40 Width = 100 Height = 100


For this problem we will use PLANE42 (2D structural solid). This element has 4 nodes, each with 2 degrees of freedom (translation along the X and Y axes).


In the window that appears, enter the following geometric properties for wood: i. Young's modulus EX: 10000 (MPa)


6. Define Mesh Size Preprocessor > Meshing > Size Cntrls > Manual Size > Areas > All Areas ...


7. Mesh the block Preprocessor > Meshing > Mesh > Areas > Free > click 'Pick All' AMESH,1




1. Define Analysis Type Solution > Analysis Type > New Analysis > Substructuring ANTYPE,SUBST

2. Select Substructuring Analysis Options

It is necessary to define the substructuring analysis options


The following window will appear. Ensure that the options are filled in as shown.

Sename (the name of the super-element matrix file) will default to the jobname. In this case, the stiffness matrix is to be generated. With the option SEPR, the stiffness matrix or load matrix can be printed to the output window if desired.

3. Select Master Degrees of Freedom

Master DOFs must be defined at the interface between the super-element and other elements in addition to points where loads/constraints are applied.

Select Solution > Master DOFs > User Selected > Define

Select the Master DOF as shown in the following figure.



In the window that appears, set the 1st degree of freedom to All DOF

4. Apply Loads Solution > Define Loads > Apply > Structural > Force/Moment > On Nodes

Place a load of 5N in the x direction on the top left hand node

The model should now appear as shown in the figure below.



5. Save the database Utility Menu > File > Save as Jobname.db SAVE

Save the database to be used again in the expansion pass


Use Pass: Using the Super-element The Use Pass is where we model the entire model, including the super-elements from the Generation Pass.


1. Clear the existing database Utility Menu > File > Clear & Start New

2. Give Use Pass a Jobname Utility Menu > File > Change Jobname ... FILNAME, USE

Enter 'USE' for the jobname




Now we need to bring the Super-element into the model

4. Define the Super-element Type Preprocessor > Element Type > Add/Edit/Delete...

Select 'Super-element' (MATRIX50)

5. Create geometry of the non-superelement (Silicone) Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners BLC4,XCORNER,YCORNER,WIDTH,HEIGHT

Create a rectangle with the dimensions (all units in mm):

XCORNER (WP X) = 0 YCORNER (WP Y) = 0 Width = 100 Height = 40

6. Define the Non-Superelement Type Preprocessor > Element Type > Add/Edit/Delete...

We will again use PLANE42 (2D structural solid).


In the window that appears, enter the following geometric properties for silicone: i. Young's modulus EX: 2.5 (MPa)


8. Define Mesh Size Preprocessor > Meshing > Size Cntrls > Manual Size > Areas > All Areas ...

For this block we will again use an element edge length of 10mm. Note that is is imperative that the nodes of the non-superelement match up with the super-element MDOFs.

9. Mesh the block Preprocessor > Meshing > Mesh > Areas > Free > click 'Pick All' AMESH,1

10. Offset Node Numbering

Since both the super-element and the non-superelement were created independently, they contain similarly numbered nodes (ie both objects will have node #1 etc.). If we bring in the super-element with similar node numbers, the nodes will overwrite existing nodes from the non-superelements. Therefore, we need to offset the super-element nodes



Determine the number of nodes in the existing model Select Utility Menu > Parameters > Get Scalar Data ... The following window will appear. Select Model Data, For Selected set as shown.

Fill in the following window as shown to set MaxNode = the highest node number

Offset the node numbering

Select Preprocessor > Modeling > Create > Elements > Super-elements > BY CS Transfer Fill in the following window as shown to offset the node numbers and save the file as GEN2



Read in the super-element matrix

Select Preprocessor > Modeling > Create > Elements > Super-elements > From .SUB File... Enter 'GEN2' as the Jobname of the matrix file in the window (shown below)

Utility Menu > Plot > Replot

11. Couple Node Pairs at Interface of Super-element and Non-Superelements

Select the nodes at the interface Select Utility Menu > Select > Entities ... The following window will appear. Select Nodes, By Location, Y coordinates, 40 as shown.

Couple the pair nodes at the interface

Select Preprocessor > Coupling / Ceqn > Coincident Nodes

Re-select all of the nodes



Select Utility Menu > Select > Entities ... In the window that appears, click 'Nodes > By Num/Pick > From Full > Sele All'



2. Apply Constraints Solution > Define Loads > Apply > Structural > Displacement > On Lines

Fix the bottom line (ie all DOF constrained)

3. Apply super-element load vectors

Determine the element number of the super-element (Select Utility Menu > PlotCtrls > Numbering...)

You should find that the super-element is element 41

Select Solution > Define Loads > Apply > Load Vector > For Super-element

The following window will appear. Fill it in as shown to apply the super-element load vector.

4. Save the database Utility Menu > File > Save as Jobname.db SAVE

Save the database to be used again in the expansion pass





1. Show the Displacement Contour Plot General Postproc > Plot Results > Contour Plot > Nodal Solution ... > DOF solution, Translation USUM PLNSOL,U,SUM,0,1

Note that only the deformation for the non-superelements is plotted. This results agree with what was found without using substructuring (see figure below).



Expansion Pass: Expanding the Results within the Super-element To obtain the solution for all elements within the super-element you will need to perform an expansion pass.


1. Clear the existing database Utility Menu > File > Clear & Start New

2. Change the Jobname back to Generation pass Jobname Utility Menu > File > Change Jobname ... FILNAME, GEN

Enter 'GEN' for the jobname

3. Resume Generation Pass Database Utility Menu > File > Resume Jobname.db ... RESUME


1. Activate Expansion Pass



Enter the Solution mode by selecting Main Menu > Solution or by typing /SOLU into the command line.

Type 'EXPASS,ON' into the command line to initiate the expansion pass.

2. Enter the Super-element name to be Expanded

Select Solution > Load STEP OPTS > ExpansionPass > Single Expand >Expand Superelem ...

The following window will appear. Fill it in as shown to select the super-element.

3. Enter the Super-element name to be Expanded

Select Solution > Load Step Opts > ExpansionPass > Single Expand > By Load Step...

The following window will appear. Fill it in as shown to expand the solution.



1. Show the Displacement Contour Plot General Postproc > Plot Results > (-Contour Plot-) Nodal Solution ... > DOF solution, Translation



USUM PLNSOL,U,SUM,0,1

Note that only the deformation for the super-elements is plotted (and that the contour intervals have been modified to begin at 0). This results agree with what was found without using substructuring (see figure below).






Coupled Structural/Thermal Analysis

Introduction This tutorial was completed using ANSYS 7.0 The purpose of this tutorial is to outline a simple coupled thermal/structural analysis. A steel link, with no internal stresses, is pinned between two solid structures at a reference temperature of 0 C (273 K). One of the solid structures is heated to a temperature of 75 C (348 K). As heat is transferred from the solid structure into the link, the link will attemp to expand. However, since it is pinned this cannot occur and as such, stress is created in the link. A steady-state solution of the resulting stress will be found to simplify the analysis.

Loads will not be applied to the link, only a temperature change of 75 degrees Celsius. The link is steel with a modulus of elasticity of 200 GPa, a thermal conductivity of 60.5 W/m*K and a thermal expansion coefficient of 12e-6 /K.

Preprocessing: Defining the Problem According to Chapter 2 of the ANSYS Coupled-Field Guide, "A sequentially coupled physics analysis is the combination of analyses from different engineering disciplines which interact to solve a global engineering problem. For convenience, ...the solutions and procedures associated with a particular engineering discipline [will be referred to as] a physics analysis. When the input of one physics analysis depends on the results from another analysis, the analyses are coupled."

Thus, each different physics environment must be constructed seperately so they can be used to determine the coupled physics solution. However, it is important to note that a single set of nodes will exist for the entire model. By creating the geometry in the first physical environment, and using it with any following coupled environments, the geometry is kept constant. For our case, we will create the geometry in the Thermal Environment, where the thermal effects will be applied.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/Coupled/Coupled.html


Although the geometry must remain constant, the element types can change. For instance, thermal elements are required for a thermal analysis while structural elements are required to deterime the stress in the link. It is important to note, however that only certain combinations of elements can be used for a coupled physics analysis. For a listing, see Chapter 2 of the ANSYS Coupled-Field Guide located in the help file.

The process requires the user to create all the necessary environments, which are basically the preprocessing portions for each environment, and write them to memory. Then in the solution phase they can be combined to solve the coupled analysis.

Thermal Environment - Create Geometry and Define Thermal Properties

1. Give example a Title Utility Menu > File > Change Title ... /title, Thermal Stress Example



We are going to define 2 keypoints for this link as given in the following table:


Create a line joining Keypoints 1 and 2, representing a link 1 meter long.


For this problem we will use the LINK33 (Thermal Mass Link 3D conduction) element. This element is a uniaxial element with the ability to conduct heat between its nodes.


In the 'Real Constants for LINK33' window, enter the following geometric properties: i. Cross-sectional area AREA: 4e-4

This defines a beam with a cross-sectional area of 2 cm X 2 cm.

Keypoint Coordinates (x,y,z)1 (0,0)2 (1,0)



7. Define Element Material Properties Preprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic

In the window that appears, enter the following geometric properties for steel: i. KXX: 60.5


For this example we will use an element edge length of 0.1 meters.


10. Write Environment The thermal environment (the geometry and thermal properties) is now fully described and can be written to memory to be used at a later time. Preprocessor > Physics > Environment > Write

In the window that appears, enter the TITLE Thermal and click OK.

11. Clear Environment Preprocessor > Physics > Environment > Clear > OK

Doing this clears all the information prescribed for the geometry, such as the element type, material properties, etc. It does not clear the geometry however, so it can be used in the next stage, which is defining the structural environment.

Structural Environment - Define Physical Properties

Since the geometry of the problem has already been defined in the previous steps, all that is required is to detail the structural variables.

1. Switch Element Type Preprocessor > Element Type > Switch Elem Type

Choose Thermal to Struc from the scoll down list.



This will switch to the complimentary structural element automatically. In this case it is LINK 8. For more information on this element, see the help file. A warning saying you should modify the new element as necessary will pop up. In this case, only the material properties need to be modified as the geometry is staying the same.


In the window that appears, enter the following geometric properties for steel: i. Young's Modulus EX: 200e9


Preprocessor > Material Props > Material Models > Structural > Thermal Expansion Coef > Isotropic

i. ALPX: 12e-6

3. Write Environment The structural environment is now fully described. Preprocessor > Physics > Environment > Write

In the window that appears, enter the TITLE Struct



2. Read in the Thermal Environment Solution > Physics > Environment > Read

Choose thermal and click OK.



If the Physics option is not available under Solution, click Unabridged Menu at the bottom of the Solution menu. This should make it visible.

3. Apply Constraints Solution > Define Loads > Apply > Thermal > Temperature > On Keypoints

Set the temperature of Keypoint 1, the left-most point, to 348 Kelvin.


5. Close the Solution Menu Main Menu > Finish

It is very important to click Finish as it closes that environment and allows a new one to be opened without contamination. If this is not done, you will get error messages.

The thermal solution has now been obtained. If you plot the steady-state temperature on the link, you will see it is a uniform 348 K, as expected. This information is saved in a file labelled Jobname.rth, were .rth is the thermal results file. Since the jobname wasn't changed at the beginning of the analysis, this data can be found as file.rth. We will use these results in determing the structural effects.

6. Read in the Structural Environment Solution > Physics > Environment > Read

Choose struct and click OK.


Fix Keypoint 1 for all DOF's and Keypoint 2 in the UX direction.



8. Include Thermal Effects Solution > Define Loads > Apply > Structural > Temperature > From Therm Analy

As shown below, enter the file name File.rth. This couples the results from the solution of the thermal environment to the information prescribed in the structural environment and uses it during the analysis.

9. Define Reference Temperature Preprocessor > Loads > Define Loads > Settings > Reference Temp

For this example set the reference temperature to 273 degrees Kelvin.






As shown, the stress in the link should be a uniform 180 MPa in compression.

2. Get Stress Data Since the element is only a line, the stress can't be listed in the normal way. Instead, an element table must be created first.

General Postproc > Element Table > Define Table > Add

Fill in the window as shown below. [CompStr > By Sequence Num > LS > LS,1 ETABLE,CompStress,LS,1

3. List the Stress Data General Postproc > Element Table > List Elem Table > COMPSTR > OK PRETAB,CompStr



The following list should appear. Note the stress in each element: -0.180e9 Pa, or 180 MPa in compression as expected.




Using P-Elements

Introduction This tutorial was completed using ANSYS 7.0. This tutorial outlines the steps necessary for solving a model meshed with p-elements. The p-method manipulates the polynomial level (p-level) of the finite element shape functions which are used to approximate the real solution. Thus, rather than increasing mesh density, the p-level can be increased to give a similar result. By keeping mesh density rather coarse, computational time can be kept to a minimum. This is the greatest advantage of using p-elements over h-elements.

A uniform load will be applied to the right hand side of the geometry shown below. The specimen was modeled as steel with a modulus of elasticity of 200 GPa.


Utility Menu > File > Change Title ... /title, P-Method Meshing

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/PElement/Print.html


2. Activate the p-Method Solution Options ANSYS Main Menu > Preferences /PMETH,ON

Select p-Method Struct. as shown below



We are going to define 12 keypoints for this geometry as given in the following table:

Keypoint Coordinates (x,y,z)1 (0,0)2 (0,100)3 (20,100)4 (45,52)5 (55,52)6 (80,100)7 (100,100)8 (100,0)9 (80,0)



5. Create Area Preprocessor > Modeling > Create > Areas > Arbitrary > Through KPs A,1,2,3,4,5,6,7,8,9,10,11,12

Click each of the keypoints in numerical order to create the area shown below.


For this problem we will use the PLANE145 (p-Elements 2D Quad) element. This element has eight nodes with 2 degrees of freedom each (translation along the X and Y axes). It can support a polynomial with maximum order of eight.

After clicking OK to select the element, click Options... to open the keyoptions window, shown below. Choose Plane stress + TK for Analysis Type.

10 (55,48)11 (45,48)12 (20,0)



Keyopts 1 and 2 can be used to set the starting and maximum p-level for this element type. For now we will leave them as default.

Other types of p-elements exist in the ANSYS library. These include Solid127 and Solid128 which have electrostatic DOF's, and Plane145, Plane146, Solid147, Solid148 and Shell150 which have structural DOF's. For more information on these elements, go to the Element Library in the help file.


In the 'Real Constants for PLANE145' window, enter the following geometric properties: i. Thickness THK: 10

This defines an element with a thickness of 10 mm.




9. Define Mesh Size Preprocessor > Meshing > Size Cntrls > ManualSize > Areas > All Areas...




Solution > Analysis Type > New Analysis > Static



ANTYPE,0

2. Set Solution Controls Solution > Analysis Type > Sol'n Controls


A) Set Time at end of loadstep to 1 and Automatic time stepping to ON B) Set Number of substeps to 20, Max no. of substeps to 100, Min no. of substeps to 20. C) Set the Frequency to Write every substep


Fix the left side of the area (ie all DOF constrained)

4. Apply Loads Solution > Define Loads > Apply > Pressure > On Lines

Apply a pressure of -100 N/mm^2





Postprocessing: Viewing the Results 1. Read in the Last Data Set

General Postproc > Read Results > Last Set

2. Plot Equivalent Stress General Postproc > Plot Results > Contour Plot > Element Solu

In the window that pops up, select Stress > von Mises SEQV



The following stress distribution should appear.

3. Plot p-Levels General Postproc > Plot Results > p-Method > p-Levels

The following distribution should appear.



Note how the order of the polynomial increased in the area with the greatest range in stress. This allowed the elements to more accurately model the stress distribution through that area. For more complex geometries, these orders may go as high as 8. As a comparison, a plot of the stress distribution for a normal h-element (PLANE2) model using the same mesh, and one with a mesh 5 times finer are shown below.



As one can see from the two plots, the mesh density had to be increased by 5 times to get the accuracy that the p-elements delivered. This is the benefit of using p-elements. You can use a mesh that is relatively coarse, thus computational time will be low, and still get reasonable results. However, care should be taken using p-elements as they can sometimes give poor results or take a long time to converge.




Melting Using Element Death

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to outline the steps required to use element death to model melting of a material. Element death is the "turning off" of elements according to some desired criterion. The elements are still technically there, they just have zero stiffness and thus have no affect on the model.

This tutorial doesn't take into account heat of fusion or changes in thermal properties over temperature ranges, rather it is concerned with the element death procedure. More accurate models using element death can then be created as required. Element birth is also possible, but will not be discussed here. For further information, see Chapter 10 of the Advanced Guide in the ANSYS help file regarding element birth and death.

The model will be an infinitely long rectangular block of material 3cm X 3cm as shown below. It will be subject to convection heating which will cause the block to "melt".


Utility Menu > File > Change Title ... /title, Element Death


University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/BirthDeath/print.html


3. Create Rectangle Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners

Fill in the window with the following dimensions: WP X = 0 WP Y = 0 Width = 0.03 Height = 0.03

BLC4,0,0,0.03,0.03



5. Define Element Material Properties Preprocessor > Material Props > Material Models > Thermal > Conductivity > Isotropic In the window that appears, enter the following properties:

i. Thermal Conductivity KXX: 1.8

Preprocessor > Material Props > Material Models > Thermal > Specific Heat In the window that appears, enter the following properties:

i. Specific Heat C: 2040

Preprocessor > Material Props > Material Models > Thermal > Density In the window that appears, enter the following properties:

i. Density DENS: 920


For this example we will use an element edge length of 0.0005m.



Solution > Analysis Type > New Analysis > Transient

The window shown below will pop up. We will use the defaults, so click OK.



ANTYPE,4

2. Turn on Newton-Raphson solver Due to a glitch in the ANSYS software, there is no apparent way to do this with the graphical user interface. Therefore, you must type NROPT,FULL into the commmand line. This step is necessary as element killing can only be done when the N-R solver has been used.

3. Set Solution Controls Solution > Analysis Type > Sol'n Controls


A) Set Time at end of loadstep to 60 and Automatic time stepping to OFF.



B) Set Number of substeps to 20. C) Set the Frequency to Write every substep.

Click on the NonLinear tab at the top and fill it in as shown

D) Set Line search to ON . E) Set the Maximum number of iterations to 100.

For a complete description of what these options do, refer to the help file. Basically, the time at the end of the load step is how long the transient analysis will run and the number of substeps defines how the load is broken up. By writing the data at every step, you can create animations over time and the other options help the problem converge quickly.

4. Apply Initial Conditions Solution > Define Loads > Apply > Initial Condit'n > Define > Pick All

Fill in the IC window as follows to set the initial temperature of the material to 268 K:

5. Apply Boundary Conditions



For thermal problems, constraints can be in the form of Temperature, Heat Flow, Convection, Heat Flux, Heat Generation, or Radiation. In this example, all external surfaces of the material will be subject to convection with a coefficient of 10 W/m^2*K and a surrounding temperature of 368 K.

Solution > Define Loads > Apply > Thermal > Convection > On Lines > Pick All

Fill in the pop-up window as follows, with a film coefficient of 10 and a bulk temperature of 368.

The model should now look as follows:



Solve the System Solution > Solve > Current LS SOLVE

Postprocessing: Prepare for Element Death 1. Read Results

General Postproc > Read Results > Last Set SET,LAST

2. Create Element Table

Element death can be used in various ways. For instance, the user can manually kill, or turn off, elements to create the desired effect. Here, we will use data from the analysis to kill the necessary elements to model melting. Assume the material melts at 273 K. We must create an element table containing the temperature of all the elements.

From the General Postprocessor menu select Element Table > Define Table...

Click on 'Add...'

Fill the window in as shown below, with a title Melty and select DOF solution > Temperature TEMP and click OK.

We can now select elements from this table in the temperature range we desire.

3. Select Elements to Kill

Assume that the melting temperature is 273 K, thus any element with a temperature of 273 or greater must be killed to simulate melting.


Use the scroll down menus to select Elements > By Results > From Full and click OK.



Ensure the element table Melty is selected and enter a VMIN value of 273 as shown.

Solution Phase: Killing Elements 1. Restart the Analysis

Solution > Analysis Type > Restart > OK

You will likely have two messages pop up at this point. Click OK to restart the analysis, and close the warning message. The reason for the warning is ANSYS defaults to a multi-frame restart, which this analysis doesn't call for, thus it is just warning the user.

2. Kill Elements



The easiest way to do this is to type ekill,all into the command line. Since all elements above melting temperature had been selected, this will kill only those elements.

The other option is to use Solution > Load Step Opts > Other > Birth & Death > Kill Elements and graphically pick all the melted elements. This is much too time consuming in this case.

Postprocessing: Viewing Results 1. Select Live Elements


Fill in the window as shown with Elements > Live Elem's > Unselect and click Sele All.

With the window still open, select Elements > Live Elem's > From Full and click OK.



2. View Results General Postproc > Plot Results > Contour Plot > Nodal Solu > DOF solution > Temperature TEMP

The final melted shape should look as follows:



This procedure can be programmed in a loop, using command line code, to more accurately model element death over time. Rather than running the analysis for a time of 60 and killing any elements above melting temperature at the end, a check can be done after each substep to see if any elements are above the specified temperature and be killed at that point. That way, the prescribed convection can then act on the elements below those killed, more accurately modelling the heating process.




Contact Elements

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to describe how to utilize contact elements to simulate how two beams react when they come into contact with each other.

The beams, as shown below, are 100mm long, 10mm x 10mm in cross-section, have a Young's modulus of 200 GPa, and are rigidly constrained at the outer ends. A 10KN load is applied to the center of the upper, causing it to bend and contact the lower.


Utility Menu > File > Change Title ... /title, Contact Elements


3. Define Areas Preprocessor > Modeling > Create > Area > Rectangle > By 2 Corners BLC4,WP X, WP Y, Width, Height

We are going to define 2 rectangles as described in the following table:

Rectangle Variables (WP X,WP Y,Width,Height)1 (0, 15, 100, 10)

www.mece.ualberta.ca/tutorials/ansys/AT/Contact/Contact.html



For this problem we will use the PLANE42 (Solid, Quad 4node 42) element. This element has 2 degrees of freedom at each node (translation along the X and Y).

While the Element Types window is still open, click Options.... Change Element behavior K3 to Plane strs w/thk as shown below. This allows a thickness to be input for the elements.


In the 'Real Constants for PLANE42' window, enter the following geometric properties: i. Thickness THK: 10

This defines a beam with a thickness of 10 mm.




7. Define Mesh Size Preprocessor > Meshing > Size Cntrls > ManualSize > Areas > All Lines...


8. Mesh the frame

2 (50, 0, 100, 10)



Preprocessor > Meshing > Mesh > Areas > Free > click 'Pick All'

9. Define the Type of Contact Element Preprocessor > Element Type > Add/Edit/Delete...

For this problem we will use the CONTAC48 (Contact, pt-to-surf 48) element. CONTAC48 may be used to represent contact and sliding between two surfaces (or between a node and a surface) in 2-D. The element has two degrees of freedom at each node: translations in the nodal x and y directions. Contact occurs when the contact node penetrates the target line.

While the Element Types window is still open, click Options.... Change Contact time/load prediction K7 to Reasonabl T/L inc. This is an important step. It initiates a process during the solution calculations where the time step or load step, depending on what the user has specified in the solution controls, incremements slowly when contact is immenent. This way, one surface won't penetrate too far into the other and cause the solution to fail.

It is important to note, CONTAC48 elements are created in the space between two surfaces prescribed by the user. This will be covered below. As the surfaces approach each other, the contact element is slowly "crushed" until it's upper node(s) lie along the same line as the lower node(s). Thus, ANSYS can calculate when the two prescribed surfaces have made contact. Other contact elements, such as CONTA175, require a target element, such as TARGE169, to function. When using contact elements in your own analyses, be sure to understand how the elements work. The ANSYS help file has plenty of useful information regarding contact elements and is worth reading.

10. Define Real Constants for the Contact Elements Preprocessor > Real Constants... > Add...

In the 'Real Constants for CONTAC48' window, enter the following properties: i. Normal contact stiffness KN: 200000

CONTAC48 elements basically use a penalty approach to model contact. When one surface comes into "contact" with the other, ANSYS numerically puts a spring of stiffness KN between the two. ANSYS recommends a value between 0.01 and 100 times Young's modulus for the material. Since this "spring" is so stiff, the behaviour of the model is like the two surfaces have made contact. This KN value can greatly



affect your solution, so be sure to read the help file on contact so you can recognize when your solution is not converging and why. A good rule of thumb is to start with a low value of KN and see how the solution converges (start watching the ANSYS Output Window). If there is too much penetration, you should increase KN. If it takes a lot of iterations to converge for a single substep, you should decrease KN.

ii. Target length tolerance TOLS: 10 Real constant TOLS is used to add a small tolerance that will internally increase the length of the target. This is useful for problems when node to node contact is likely to occur, rather than node to element edge. In this situation, the contact node may repeatedly "slip" off one of the target nodes, resulting in convergence difficulties. A small value of TOLS, given in %, is usually enough to prevent such difficulties.

The other real constants can be used to model sliding friction, tolerances, etc. Information about these other constants can be found in the help file.

11. Define Nodes for Creating Contact Elements Unlike the normal meshing sequence used for most elements, contact elements must be defined in a slightly different manner. Sets of nodes that are likely to come into contact must be defined and used to generate the necessary elements. ANSYS has many recommendations about which nodes to select and whether they should act as target nodes or source nodes. In this simple case, source nodes are those that will move into contact with the other surface, where as target nodes are those that are contacted. These terms are important when using the automatic contact element mesher to ensure the elements will correctly model contact between the surfaces. A strong understanding of how the elements work is important when using contact elements for your own analysis.

First, the source nodes will be selected. Utility Menu > Select > Entities... Select Areas and By Num/Pick from the pull down menus, select From Full from the radio buttons and click OK. Select the top beam and click OK. This will ensure any nodes that are selected in the next few steps will be from the upper beam. In this case, it is not too hard to ensure you select the correct nodes. However, when the geometry is complex, you may inadvertantly select a node from the wrong surface and it could cause problems during element generation.



Utility Menu > Select > Entities... Select Nodes and By Location from the pull down menus, Y coordinates and Reselect from the radio buttons and enter a value of 15 and click OK. This will select all nodes along the bottom of the upper beam.

Utility Menu > Select > Entities... Select Nodes and By Location from the pull down menus, X coordinates and Reselect from the radio buttons and enter values of 50,100. This will select the nodes



above the lower beam.

Now if you list the selected nodes, Utility Menu > List > Nodes... you should only have the following nodes remaining.



It is important to try and limit the number of nodes you use to create contact elements. If you have a lot of contact elements, it takes a great deal of computational time to reach a solution. In this case, the only nodes that could make contact with the lower beam are those directly above it, thus those are the only nodes we will use to create the contact elements.

Utility Menu > Select > Comp/Assembly > Create Component Enter the component name Source as shown below, and click OK. Now we can use this component, Source, as a list of nodes to be used in other functions. This can be very useful in other applications as well.

Now select the target nodes. Using the same procedure as above, select the nodes on the lower beam directly under the upper beam. Be sure to reselect all nodes before starting to select others. This is done by



opening the entity select menu, Utility Menu > Select > Entities..., clicking the Also Selectradio button, and click the Sele All button. These values will be the ones you'll use.

Click the lower area for the area select. The Y coordinate is 10 The X coordinates vary from 50 to 100.

When creating the component this time, enter the name Target.

IMPORTANT: Be sure to reselect all the nodes before continuing. This is done by opening the entity select menu, Utility Menu > Select > Entities..., clicking the Also Select radio button, and click the Sele All button.

12. Generate Contact Elements Main Menu > Preprocessor > Modeling > Create > Elements > Elem Attributes

Fill the window in as shown below. This ensures ANSYS knows that you are dealing with the contact elements and the associated real constants.

Main Menu > Preprocessor > Modeling> Create > Elements > Surf / Contact > Node to Surf

The following window will pop up. Select the node set SOURCE from the first drop down menu (Ccomp) and TARGET from the second drop down menu (Tcomp). The rest of the selections remain unchanged.



At this point, your model should look like the following.

Unfortunately, the contact elements don't get plotted on the screen so it is sometimes difficult to tell they are there. If you wish, you can plot the elements (Utility Menu > Plot > Elements) and turn on element numbering (Utility Menu > PlotCtrls > Numbering > Elem/Attrib numbering > Element Type Numbers). If you zoom in on the contact areas, you can see little purple stars (Contact Nodes) and thin purple lines (Target Elements) numbered "2" which correspond to the contact elements, shown below.



The preprocessor stage is now complete.









A. Ensure Automatic time stepping is on. Automatic time stepping allows ANSYS to determine appropriate sizes to break the load steps into. Decreasing the step size usually ensures better accuracy, however, this takes time. The Automatic Time Step feature will determine an appropriate balance. This feature also activates the ANSYS bisection feature which will allow recovery if convergence fails.

B. Enter 100 as the number of substeps. This will set the initial substep to 1/100 th of the total load.

C. Enter a maximum number of substeps of 1000. This stops the program if the solution does not converge after 1000 steps.

D. Enter a minimum number of substeps of 20.

E. Ensure all solution items are writen to a results file.


A. Ensure Maximum Number of Iterations is set to 100




These solution control values are extremely important in determining if your analysis will succeed or fail. If you have too few substeps, the contact nodes may be driven through the target elements before ANSYS "realizes" it has happened. In this case the solution will resemble that of an analysis that didn't have contact elements defined at all. Therefore it is important to choose a relatively large number of substeps initially to ensure the model is defined properly. Once everything is working, you can reduce the number of substeps to optimize the computational time. Also, if the maximum number of substeps or iterations is left too low, ANSYS may stop the analysis before it has a chance to converge to a solution. Again, leave these relatively high at first.


Fix the left end of the upper beam and the right end of the lower beam (ie all DOF constrained)

4. Apply Loads Solution > Define Loads > Apply > Structural > Force/Moment > On Nodes

Apply a load of -10000 in the FY direction to the center of the top surface of the upper beam. Note, this is a point load on a 2D surface. This type of loading should be avoided since it will cause a singularity. However, the displacement or stress near the load is not of interest in this analyis, thus we will use a point load for simplicity.





Postprocessing: Viewing the Results 1. Open postprocessor menu

ANSYS Main Menu > General Postproc /POST1

2. Adjust Graphical Scaling Utility Menu > PlotCtrls > Style > Displacement Scaling

Click the 1.0 (true scale) radio button, then click ok. This is of huge importance! I lost many hours trying to figure out why the contact elements weren't working, when in fact it was just due to the displacement scaling to which ANSYS defaulted. If you leave the scaling as default, many times it will look like your contact nodes have gone through the target elements.

3. Show the Stress Distribution in the Beams General Postproc > Plot Results > Contour Plot > Nodal Solu > Stress > von Mises

4. Adjust Contour Scale Utility Menu > PlotCtrls > Style > Contours > Non-Uniform Contours

Fill in the window as follows:



This should produce the following stress distribution plot:

As seen in the figure, the load on the upper beam caused it to deflect and come in contact with the lower beam, producing a stress distribution in both.






ANSYS Parametric Design Language (APDL)

Introduction This tutorial was completed using ANSYS 7.0 The purpose of this tutorial is to familiarize the user with the ANSYS Parametric Design Language (APDL). This will be a very basic introduction to APDL, covering things like variable definition and simple looping. Users familiar with basic programming languages will probably find the APDL very easy to use. To learn more about APDL and see more complex examples, please see the APDL Programmer's Guide located in the help file.

This tutorial will cover the preprocessing stage of constructing a truss geometry. Variables including length, height and number of divisions of the truss will be requested and the APDL code will construct the geometry.

Preprocessing: Use of APDL Shown below is the APDL code used to construct the truss shown above, using a length of 200 m, a height of 10 m and 20 divisions. The following discussion will attempt to explain the commands used in the code. It is assumed the user has been exposed to basic coding and can follow the logic.

finish /clear /prep7 *ask,LENGTH,How long is the truss,100 *ask,HEIGHT,How tall is the truss,20 *ask,DIVISION,How many cross supports even number,2 DELTA_L = (LENGTH/(DIVISION/2))/2 NUM_K = DIVISION + 1 COUNT = -1 X_COORD = 0 *do,i,1,NUM_K,1 COUNT = COUNT + 1 OSCILATE = (-1)**COUNT X_COORD = X_COORD + DELTA_L

http://www.mece.ualberta.ca/tutorials/ansys/at/apdl/apdl.html


*if,OSCILATE,GT,0,THEN k,i,X_COORD,0 *else k,i,X_COORD,HEIGHT *endif *enddo KEYP = 0 *do,j,1,DIVISION,1 KEYP = KEYP + 1 L,KEYP,(KEYP+1) *if,KEYP,LE,(DIVISION-1),THEN L,KEYP,(KEYP+2) *endif *enddo et,1,link1 r,1,100 mp,ex,1,200000 mp,prxy,1,0.3 esize,,1 lmesh,all finish

1. *ASK Command The *ASK command prompts the user to input data for a variable. In this case, *ask,LENGTH,How long is the truss,100 prompts the user for a value describing the length of the truss. This value is stored under the variable LENGTH. Thus in later parts of the code, LENGTH can be used in other commands rather than typing in 200 m. The 100 value at the end of the string is the default value if the user were to enter no value and just hit the enter key.

2. Variable Definition Using the "=" Command ANSYS allows the user to define a variable in a few ways. As seen above, the *ASK command can be used define a variable, but this is usually only used for data that will change from run to run. The *SET command can also be used to define variables. For more information on this command, see the help file. However, the most intutitive method is to use "=". It is used in the following manner: 'the variable you wish to define' = 'some arguement'. This argument can be a single value, or a mathematical expression, as seen in the line defining DELTA_L

3. *DO Loops Do-loops are useful when you want to repeat a command a known number of times. The syntax for the expression is *DO, Par, IVAL, FVAL, INC, where Par is the parameter that will be incremented by the loop, IVAL is the initial value the parameter starts as, FVAL is the final value the parameter will reach, and INC is the increment value that the parameter



will be increased by during each iteration of the loop. For example, *do,i,1,10_K,1 is a do-loop which increases the parameter "i" from 1 to 10 in steps of 1, (ie 1,2,3...8,9,10). It is necessary to use a *ENDDO command at the end of the loop to locate where ANSYS should look for the next command once the loop has finished. In between the *DO and *ENDDO, the user can place code that will utilize the repetative characteristics of the loop.

4. *IF Statement If-statements can be used as decision makers, determining if a certain case has occured. For example, in the code above there is a statement: *if,OSCILATE,GT,0,THEN. This translates to "if the variable, OSCILATE, is greater than zero, then...". Any code directly following the *if command will be carried out if the statement is true. If it is not true it will skip to the *else command. This command is only used in conjunction with the *if command. Any code directly following the *else command will be carried out when the original statement is false. An *endif command is necessary after all code in the *if and *else sections to define an ending.





Introduction This tutorial was created using ANSYS 6.1 The purpose of this tutorial is to outline the steps required to view cross sectional results (Deformation, Stress, etc.) of the following example.


Utility Menu > File > Change Title ... /title, Cross-Sectional Results of a Simple Cantilever Beam


3. Create Block Preprocessor > Modeling > Create > Volumes > Block > By 2 Corners & Z BLC4,0,0,Width,Height,Length


For this problem we will use the SOLID45 (3D Structural Solid) element. This element has 8 nodes

Where: Width: 40mmHeight: 60mmLength: 400mm

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/Slice/Slice.html


each with 3 degrees of freedom (translation along the X, Y and Z directions).




6. Define Mesh Size Preprocessor > Meshing > Size Cntrls > ManualSize > Global > Size esize,20

For this example we will use an element size of 20mm.

7. Mesh the volume Preprocessor > Meshing > Mesh > Volumes > click 'Pick All' vmesh,all



2. Apply Constraints Solution > Define Loads > Apply > Structural > Displacement > On Areas Fix the left hand side (should be labeled Area 1).

3. Apply Loads Solution > Define Loads > Apply > Structural > Force/Moment > On Keypoints Apply a load of 2500N downward on the back right hand keypoint (Keypoint #7).

4. Solve the System Solution > (-Solve-) Current LS SOLVE

Postprocessing: Viewing the Results Now since the purpose of this tutorial is to observe results within different cross-sections of the colume, we will first outline the steps required to view a slice.

Offset the working plane for a cross section view (WPOFFS)

Select the TYPE of display for the section(/TYPE). For this example we are trying to display a section, therefore, options 1, 5, or 8 are relevant and are summarized in the table below.



Align the cutting plane with the working plane(/CPLANE)

1. Deflection

Before we begin selecting cross sections, let's view deflection of the entire model.

Select: General Postproc > Plot Results > Contour Plot > Nodal Solu

Type Description Visual Representation

SECT or (1)

Section display. Only the selected section is shown without any remaining faces or edges shown

CAP or (5)

Capped hidden diplay. This is as though you have cut off a portion of the model and the remaining model can be seen

ZQSL or (8)

QSLICE Z-buffered display. This is the same as SECT but the outline of the entire model is shown.



From this one may wish to view several cross sections through the YZ plane.

To illustrate how to take a cross section, let's take one halfway through the beam in the YZ plane

First, offset the working plane to the desired position, halfway through the beam Select: Utility Menu > WorkPlane > Offset WP by Increments In the window that appears, increase Global X to 30 (Width/2) and rotate Y by +90 degrees

Select the type of plot and align the cutting plane with the working plane (Note that in GUI, these two steps are combined) Select: Utility Menu > PlotCtrls > Style > Hidden-Line Options

Fill in the window that appears as shown below to select /TYPE=ZQSL and /CPLANE=Working Plane



As desired, you should now have the following:

This can be repeated for any slice, however, note that the command lines required to do the same are as follows:

WPOFFS,Width/2,0,0 ! Offset the working plane for cross-section view WPROTA,0,0,90 ! Rotate the working plane /CPLANE,1 ! Cutting plane defined to use the WP /TYPE,1,8 PLNSOL,U,SUM,0,1



Also note that to realign the working plane with the active coordinate system, simply use: WPCSYS,-1,0

2. Equivalent Stress

Again, let's view stresses within the entire model.

First we need to realign the working plane with the active coordinate system. Select: Utility Menu > WorkPlane > Align WP with > Active Coord Sys (NOTE: To check the position of the WP, select Utility Menu > WorkPlane > Show WP Status)

Next we need to change /TYPE to the default setting(no hidden or section operations). Select: Utility Menu > PlotCtrls > Style > Hidden Line Options... And change the 'Type of Plot' to 'Non-hidden'

Select: General Postproc > Plot Results > Contour Plot > Nodal Solu > Stress > von Mises

Let's say that we want to take a closer look at the base of the beam through the XY plane. Because it is much easier, we are going to use command line:

WPOFFS,0,0,1/16*Length ! Offset the working plane /CPLANE,1 ! Cutting plane defined to use the WP /TYPE,1,5 ! Use the capped hidden display PLNSOL,S,EQV,0,1

Note that we did not need to rotate the WP because we want to look at the XY plane which is the default). Also note that we are using the capped hidden display this time.



You should now see the following:

3. Animation

Now, for something a little more impressive, let's show an animation of the Von Mises stress through the beam. Unfortunately, the ANSYS commands are not as user friendly as they could be... but please bear with me.

Select: Utility Menu > PlotCtrls > Animate > Q-Slice Contours

In the window that appears, just change the Item to be contoured to 'Stress' 'von Mises'

You will then be asked to select 3 nodes; the origin, the sweep direction, and the Y axis. In the graphics window, select the node at the origin of the coordinate system as the origin of the sweep (the sweep will start there). Next, the sweep direction is in the Z direction, so select any node in the z direction (parallel to the first node). Finally, select the node in the back, bottom left hand side corner as the Y axis.

You should now see an animated version of the contour slices through the beam. For more information on how to modify the animation, type help ancut into the command line.



Using Paths to Post Process Results

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to create and use 'paths' to provide extra detail during post processing. For example, one may want to determine the effects of stress concentrators along a certain path. Rather than plotting the entire contour plot, a plot of the stress along that path can be made.

In this tutorial, a steel plate measuring 100 mm X 200 mm X 10 mm will be used. Three holes are drilled through the vertical centerline of the plate. The plate is constrained in the y-direction at the bottom and a uniform, distributed load is pulling on the top of the plate.

Preprocessing: Defining the Problem 1. Give the example a Title

Utility Menu > File > Change Title ... /title, Use of Paths for Post Processing


3. Define Rectangular Ares Preprocessor > Modeling > Create > Areas > Rectangle > By 2 Corners

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/AT/AdvancedX-SecResults/...


BLC4,0,0,200,100

Create a rectangle where the bottom left corner has the coordinates 0,0 and the width and height are 200 and 100 respectively.

4. Create Circles Preprocessor > Modeling > Create > Areas > Circle > Solid Circle cyl4,WP X,WP Y,Radius

Create three circles with parameters shown below.

5. Subtract the Circles Preprocessor > Modeling > Operate > Booleans > Subtract > Areas

First, select the area to remain (ie. the rectangle) and click OK. Then, select the areas to be subtracted (ie. the circles) and click OK.

The remaining area should look as shown below.


CircleParameters

WP X

WP Y Radius

1 50 50 10 2 100 50 10 3 150 50 10



Preprocessor > Element Type > Add/Edit/Delete...

For this problem we will use the PLANE2 (Solid Triangle 6node) element. This element has 2 degrees of freedom (translation along the X and Y axes).

In the 'Element Types' window, click 'Options...' and set 'Element behavior' to Plane strs w/thk


In the 'Real Constants for PLANE2' window, enter a thickness of 10.






10. Mesh the Area Preprocessor > Meshing > Mesh > Areas > Free > click 'Pick All'




Constrain the bottom of the area in the UY direction.

3. Apply Loads Solution > Define Loads > Apply > Structural > Pressure > On Lines

Apply a constant, uniform pressure of -200 on the top of the area.

The model should now look like the figure below.




Postprocessing: Viewing the Results To see the stress distribution on the plate, you could create a normal contour plot, which would have the distribution over the entire plate. However, if the stress near the holes are of interest, you could create a path through the center of the plate and plot the stress on that path. Both cases will be plotted below on a split screen.

1. Contour Plot

Utility Menu > PlotCtrls > Window Controls > Window Layout

Fill in the 'Window Layout' as seen below



General Postproc > Plot Results > Contour Plot > Nodal Solu > Stress > von Mises

The display should now look like this.

To ensure the top plot is not erased when the second plot is created, you must make a couple of changes.

Utility Menu > PlotCtrls > Window Controls > Window On or Off. Turn window 1 'off'.

To keep window 1 visible during replots, select Utility Menu > PlotCtrls > Erase Option > Erase Between Plots and ensure there is no check-mark, meaning this function off.



To have the next graph plot in the bottom half of the screen, select Utility Menu > PlotCtrls > Window Controls > Window Layout and select 'Window 2 > Bottom Half > Do not replot'.

2. Create Path

General PostProc > Path Operations > Define Path > By Location

In the window, shown below, name the path Cutline and set the 'Number of divisions' to 1000

Fill the next two window in with the following parameters

When the third window pops up, click 'Cancle' because we only enabled two points on the path in the previous step.

3. Map the Stress onto the Path

Now the path is defined, you must choose what to map to the path, or in other words, what results should be available to the path. For this example, equivalent stress is desired.

General Postproc > Path Operations > Map onto Path

Fill the next window in as shown below [Stress > von Mises] and click OK.

Parameters

Path Point Number X Loc

Y Loc

Z Loc

1 0 50 0 2 200 50 0



The warning shown below will probably pop up. This is just saying that some of the 1000 points you defined earlier are not on interpolation points (special points on the elements) therefore there is no data to map. This is of little concern though, since there are plenty of points that do lie on interpolation points to produce the necessary plot, so disregard the warning.

4. Plot the Path Data

General Postproc > Path Operations > Plot Path Item > On Geometry

Fill the window in as shown below



The display should look like the following. Note, there will be dots on the plot showing node locations. Due to resolution restrictions, these dots are not shown here.

This plot makes it easy to see how the stress is concentrated around the holes.






Using Tables to Post Process Results

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to outline the steps required to plot Vertical Deflection vs. Length of the following beam using tables, a special type of array. By plotting this data on a curve, rather than using a contour plot, finer resolution can be achieved.

This tutorial will use a steel beam 400 mm long, with a 40 mm X 60 mm cross section as shown above. It will be rigidly constrained at one end and a -2500 N load will be applied to the other.

Preprocessing: Defining the Problem 1. Give the example a Title

Utility Menu > File > Change Title ... /title, Use of Tables for Data Plots



We are going to define 2 keypoints for this beam as given in the following table:

Keypoint Coordinates (x,y,z)









ii. Area moment of inertia IZZ: 320e3 iii. Total beam height: 40










1 (0,0)2 (400,0)




Fix keypoint 1 (ie all DOF constrained)

3. Apply Loads Solution > Define Loads > Apply > Structural > Force/Moment > On Keypoints Apply a load of -2500N on keypoint 2.

The model should now look like the figure below.


Postprocessing: Viewing the Results It is at this point the tables come into play. Tables, a special type of array, are basically matrices that can be used to store and process data from the analysis that was just run. This example is a simplified use of tables, but they can be used for much more. For more information type help in the command line and search for 'Array Parameters'.

1. Number of Nodes

Since we wish to plot the verticle deflection vs length of the beam, the location and verticle deflection of each node must be recorded in the table. Therefore, it is necessary to determine how many nodes exist in



the model. Utility Menu > List > Nodes... > OK. For this example there are 21 nodes. Thus the table must have at least 21 rows.

2. Create the Table

Utility Menu > Parameters > Array Parameters > Define/Edit > Add

The window seen above will pop up. Fill it out as shown [Graph > Table > 22,2,1]. Note there are 22 rows, one more than the number of nodes. The reason for this will be explained below. Click OK and then close the 'Define/Edit' window.

3. Enter Data into Table

First, the horizontal location of the nodes will be recorded

Utility Menu > Parameters > Get Array Data ...

In the window shown below, select Model Data > Nodes

Fill the next window in as shown below and click OK [Graph(1,1) > All > Location > X]. Naming the array parameter 'Graph(1,1)' fills in the table starting in row 1, column 1, and continues down the column.



Next, the vertical displacement will be recorded.

Utility Menu > Parameters > Get Array Data ... > Results data > Nodal results

Fill the next window in as shown below and click OK [Graph(1,2) > All > DOF solution > UY]. Naming the array parameter 'Graph(1,2)' fills in the table starting in row 1, column 2, and continues down the column.

4. Arrange the Data for Ploting

Users familiar with the way ANSYS numbers nodes will realize that node 1 will be on the far left, as it is keypoint 1, node 2 will be on the far right (keypoint 2), and the rest of the nodes are numbered sequentially from left to right. Thus, the second row in the table contains the data for the last node. This causes problems during plotting, thus the information for the last node must be moved to the final row of the table. This is why a table with 22 rows was created, to provide room to move this data.

Utility Menu > Parameters > Array Parameters > Define/Edit > Edit



The data for the end of the beam (X-location = 400, UY = -0.833) is in row two. Cut one of the cells to be moved (right click > Copy or Ctrl+X), press the down arrow to get to the bottom of the table, and paste it into the appropriate column (right click > Paste or Ctrl+V). When both values have been moved check to ensure the two entries in row 2 are zero. Select File > Apply/Quit

5. Plot the Data

Utility Menu > Plot > Array Parameters

The following window will pop up. Fill it in as shown, with the X-location data on the X-axis and the vertical deflection on the Y-axis.



To change the axis labels select Utility Menu > Plot Ctrls > Style > Graphs > Modify Axes ...

To see the changes to the labels, select Utility Menu > Replot

The plot should look like the one seen below.






Changing Graphical Properties

Introduction This tutorial was created using ANSYS 7.0 This tutorial covers some of the methods that can be employed to change how the output to the screen looks. For instance, changing the background colour, numbering the nodes, etc.

Since the purpose of this tutorial is not to build or analysis a model, please copy the following code and paste it into the input line below the utility menu.

finish /clear /title, Changing Graphical Properties /prep7 K,1,0,0 K,2,100,0 L,1,2 et,1,beam3 r,1,100,833.333,10 mp,ex,1,200000 mp,prxy,1,0.3 esize,5 lmesh,all finish /solu antype,0 dk,1,all,all fk,2,fy,-100 solve finish

You should obtain the following screen:

http://www.mece.ualberta.ca/tutorials/ansys/pp/colours/colours.html


Graphical Options 1. Number the Nodes

Utility Menu > PlotCtrls > Numbering...




From this window you can select which items you wish to number. When you click OK, the window will disappear and your model should be numbered appropriately. However, sometimes the numbers won't show up. This could be because you had previously selected a plot of a different item. To remedy this problem, select the same item you just numbered from the Utility > Plot menu and the numbering will show up.

For instance, select the node numbering and plot the nodes. You should get the following:



As shown, the nodes have been numbered. You can also see some other information that ANSYS is providing. The arrows on the left and the right are the force that was applied and the resulting external reactive forces and moments. The triangles on the left are the constraints and the coordinate triad is also visible. These extra symbols may not be necessary, so the next section will show how to turn these symbols off.

2. Symbol Toggles Utility Menu > PlotCtrls > Symbols



This window allows the user to toggle many symbols on or off. In our case, there are no Surface or Body Loads, or Initial Conditions, so those sections won't be used. Under the Boundary conditions section, click on None to turn off all the force and reaction symbols.

The result should be as follows:



3. Triad Toggle Utility Menu > PlotCtrls > Window Controls > Window Options



This window also allows the user to toggle many things on and off. In this case, it is things associated with the window background. As shown in the window, the legend or title can be turned off, etc. To turn off the triad, select Not Shown from the Location of triad drop down menu. The following output should be the result. Notice how it is much easier to see the node numbers near the origin now.



4. Element Shape Utility Menu > PlotCtrls > Style > Size and Shape...



When using line elements, such as BEAM3, it is sometime difficult to visualize what the elements really look like. To aid in this process, ANSYS can display the elements shapes based on the real constant description. Click on the toggle box beside [/ESHAPE] to turn on element shapes and click OK to close the window.

If there is no change in output, don't be alarmed. Recall we selected a plot of just the nodes, thus elements are not going to show up. Select Utility Menu > Plot > Elements. The following should appear.



As shown, the elements are no longer just a line, but they have volume according to the real constants. To get a better 3-D view of the model, you can change the view orientation.

5. View Orientation Utility Menu > PlotCtrls > Pan Zoom Rotate...

This window allows the user to rotate the view, translate the view and zoom. You can also select predefined views, such as isometric or oblique. Basic rotating, translating and zooming can also be done using the mouse. This is very handy when you just want to



quickly change the orientation of the model. By holding the Control button on the keyboard and holding the Left mouse button the model will translate. By holding the Control button on the keyboard and holding the Middle mouse button the model will zoom or rotate on the plane of the screen. By holding the Control button on the keyboard and holding the Right mouse button the model will rotate about all axis. Using these options, it's easy to see the elements in 3-D.

6. Changing Contours First, plot the deformation contour for the beam.

General Postproc > Plot Results > Contour Plot > Nodal Solution > DOF Solution > USUM

If the contour divisions are not appropriate, they can be changed.

Utility Meny > PlotCtrls > Style > Contours

Either Uniform or Non-uniform Contours can be selected. Under uniform contours, be sure to click on User specified if you are inputing your own contour divisions. Under non-uniform contours, you can create a logarithmic contour division or some similiar contour where uniform divisions don't capture the information you desire.

If you don't like the colours of the contour, those can also be changed.

Utility Menu > PlotCtrls > Style > Colours > Contour Colours...

The colours for each division can be selected from the drop down menus.



7. Changing Background Colour Perhaps you desire to use a plot for a presentation, but don't want a black background.

Utility Menu > PlotCtrls > Style > Colours > Window Colours...

Select the background colour you desire for the window you desire. Here we are only using Window 1, and we'll set the background colour to white.



The resulting display is shown below. Notice how all the text disappeared. This is because the text colour is also white. If there is information that needs to be added, such as contour values, this can be done in other graphic editors. To save the display, select Utility Menu > PlotCtrls > Capture Image. Under the File heading, select Save As...

There are lots of other option that can be used to change the presentation of data in ANSYS, these are just a few. If you are looking for a specific option, the PlotCtrls menu is a good place to start, as is the help file.



UofA ANSYS Tutorial

ANSYSUTILITIES

BASICTUTORIALS


ADVANCEDTUTORIALS

POSTPROC.TUTORIALS

COMMANDLINE FILES

PRINTABLEVERSION

Creating Files

Features

Basic Tutorials


Advanced Tutorials

PostProc Tutorials

Radiation

Index

Contributions

Comments

MecE 563



ANSYS Inc.


ANSYS Command File Creation and Execution

Generating the Command File

There are two choices to generate the command file:

Directly type in the commands into a text file from scratch. This assumes a good knowledge of theANSYS command language and the associated options.

If you know what some of the commands and are unsure of others, execute the desired operationfrom the GUI and then go to File -> List -> Log File. This will then open up a new windowshowing the command line equivialent of all commands entered to this point. You may directlycut and paste from here to a text editor, or if you'd like to save the whole file, see the next item inthis list.

1.

Setup and solve the problem as you normally would using the ANSYS graphic user interface(GUI). Then before you are finished, enter the command File -> Save DB Log File This savesthe equivalent ANSYS commands that you entered in the GUI mode, to a text file. You can nowedit this file with a text editor to clean it up, delete errors from your GUI use and make changes asdesired.

2.

Running the Command File

To run the ANSYS command file,

save the ASCII text commands in a text file; e.g. frame.cmdstart up either the GUI or text mode of ANSYS

GUI Command File Loading

To run this command file from the GUI, you would do the following:

From the File menu, select Read Input from.... Change to the appropriate directory wherethe file (frame.cmd) is stored and select it.Now ANSYS will execute the commands from that file. The output window shows the progress ofthis procedure. Any errors and warnings will be listed in this window.When it is complete, you may not have a full view of your structure in the graphic window. Youmay need to select Plot -> Elements or Plot -> Lines or what have you.Assuming that the analysis worked properly, you can now use the post-processor to view elementdeflections, stress, etc.If you want to fix some errors or make some changes to the command file, make those changes ina separate window in a text editor. Save those changes to disk.To rerun the command file, you should first of all clear the current model from ANSYS. SelectFile -> Clear & Start New.Then read in the file as before File -> Read Input from...

Command Line File Loading

Alternatively, you can also read in the command file right from the ANSYS command line. Assumingthat you started ANSYS using the commands...

/ansys52/bin/ansysu52

and then entered

/show,x11c

This has now started ANSYS in the text mode and has told it what graphic device to use (in this case anX Windows, X11c, mode). At this point you could type in /menu,on, but you might not want to turn on

the full graphic mode if working on a slow machine or if you are executing the program remotely. Let'sassume that we don't turn the menu mode on...

If the command file is in the current directory for ANSYS, then from the ANSYS input window, type

/input,frame,cmd

and yes that is a comma (,) between frame and cmd. If ANSYS can not find the file in the currentdirectory, you may need to point it to the proper directory. If the file was in the directory, /myfiles/ansys/frame for example, you would use the following syntax

/input,frame,cmd,/myfiles/ansys/frame

If you want to rerun a new or modified file, it is necessary to clear the current model in memory withthe command

/clear,start

This full procedure of loading in command files and clearing jobs and starting over again can becompleted as many times as desired.

ANSYS Command Groupings

ANSYS contains hundreds of commands for generating geometry, applying loads and constraints, settingup different analysis types and post-processing. The following is only a brief summary of some of themore common commands used for structural analysis.

Category Command Description Syntax

BasicGeometry

k keypoint definition k,kp#,xcoord,ycoord,zcoord

l straight line creation l,kp1,kp2

larccircular arc line(from keypoints)

larc,kp1,kp2,kp3,rad(kp3 defines plane)

circlecircular line creation(creates keypoints)

see online help

splinespline line throughkeypoints

spline,kp1,kp2, ... kp6

aarea definition fromkeypoints

a,kp1,kp2, ... kp18

al area definition from lines a,l1,l2, ... l10

vvolume definition fromkeypoints

v,kp1,kp2, ... kp8

vavolume definition fromareas

va,a1,a2, ... a10

vextcreate volume from areaextrusion

see online help

vdragcreate volume by draggingarea along path

see online help

SolidModeling(Primitives)

rectng rectangle creation rectng,x1,x2,y1,y2

block block volume creation block,x1,x2,y1,y2,z1,z2

cylindcylindrical volumecreation

cylind,rad1,rad2,z1,z2,theta1,theta2

sphere spherical volume creation sphere,rad1,rad2,theta1,theta2

prismconetorus

various volume creationcommands

see online help

BooleanOperations

aaddadds separate areas tocreate single area

aadd,a1,a2, ... a9

aglue

creates new areas byglueing(properties remainseparate)

aglue,a1,a2, ... a9

asbacreat new area by areasubstraction

asba,a1,a2

ainacreate new area by areaintersection

aina,a1,a2, ... a9

vaddvlguevsbvvinv

volume boolean operations see online help

Elements &Meshing

et defines element typeet,number,typemay define as many as required; current typeis set by type

typeset current element typepointer

type,number

rdefine real constants forelements

r,number,r1,r2, ... r6may define as many as required; current typeis set by real

realsets current real constantpointer

real,number

mpsets material properties forelements

mp,label,number,c0,c1, ... c4may define as many as required; current typeis set by mat

matsets current materialproperty pointer

mat,number

esizesets size or number ofdivisions on lines

esize,size,ndivsuse either size or ndivs

eshape controls element shape see online help

lmesh mesh line(s)lmesh,line1,line2,incor lmesh,all

amesh mesh area(s)amesh,area1,area2,incor amesh,all

vmesh mesh volume(s)vmesh,vol1,vol2,incor vmesh,all

Sets &Selection

kselselect a subset ofkeypoints

see online help

nsel select a subset of nodes see online help

lsel select a subjset of lines see online help

asel select a subset of areas see online help

nslaselect nodes withinselected area(s)

see online help

allselselect everythingi.e. reset selection

allsel

Constraints dkdefines a DOF constrainton a keypoint

dk,kp#,label,valuelabels: UX,UY,UZ,ROTX,ROTY,ROTZ,ALL

ddefines a DOF constrainton a node

d,node#,label,valuelabels: UX,UY,UZ,ROTX,ROTY,ROTZ,ALL

dldefines (anti)symmetryDOF constraints on a line

dl,line#,area#,labellabels: SYMM (symmetry); ASYM(antisymmetry)

Loads fk defines afk,kp#,label,valuelabels: FX,FY,FZ,MX,MY,MZ

f defines a force at a nodef,node#,label,valuelabels: FX,FY,FZ,MX,MY,MZ

UofA ANSYS Tutorial

ANSYSUTILITIES

BASICTUTORIALS


ADVANCEDTUTORIALS

POSTPROC.TUTORIALS

COMMANDLINE FILES

PRINTABLEVERSION

Creating Files

Features

Basic Tutorials


Advanced Tutorials

PostProc Tutorials

Radiation

Index

Contributions

Comments

MecE 563



ANSYS Inc.


ANSYS Command File Programming Features

The following ANSYS command listing, shows some of the commonly used programming features in theANSYS command file language known as ADPL (ANSYS Parametric Design Language). It illustrates:

entering parameters (variables)prompting the user for parametersperforming calculations with paramaters; note that the syntax and functions are similar toFORTRANcontrol structures

if - then - else - endiflooping

This example file does not do anything really useful in itself besides generate keypoints along a line, butit does illustrate some of the "programming features" of the ANSYS command language.

!/PREP7 ! preprocessor phase!x1 = 5 ! define some parametersx2 = 10*ask,ndivs,Enter number of divisions (default 5),5 !! the above command prompts the user for input to be entered into the ! variable "ndivs"; if only is entered, a default of "5" is used!*IF,ndivs,GT,1,THEN ! if "ndivs" is greater than "1" dx = (x2-x1)/ndivs *DO,i,1,ndivs+1,1 ! do i = 1, ndivs + 1 (in steps of one) x = x1 + dx*(i-1) k,i,x,0,0 *ENDDO*ELSE k,1,x1,0,0 k,2,x2,0,0*ENDIF!/pnum,kp,1 ! turn keypoint numbering onkplot ! plot keypointsklist,all,,,coord ! list all keypoints with coordinates


Introduction This tutorial was created using ANSYS 7.0 to solve a simple 2D Truss problem. This is the first of four introductory ANSYS tutorials.

Problem Description

Determine the nodal deflections, reaction forces, and stress for the truss system shown below. Note that Young's Modulus, E, is 200GPa while the crass sectional area, A, is 3250mm2 for all of the elements.

(Modified from Chandrupatla & Belegunda, Introduction to Finite Elements in Engineering, p.123)

ANSYS Command Listing ! ANSYS command file to perform 2D Truss Tutorial (Chandrupatla p.123) ! /title, Bridge Truss Tutorial /PREP7 ! preprocessor phase ! ! define parameters (mm) height = 3118 width = 3600 ! ! define keypoints ! K,1, 0, 0 ! keypoint, #, x, y K,2, width/2,height K,3, width, 0 K,4, 3*width/2, height K,5, 2*width, 0 K,6, 5*width/2, height K,7, 3*width, 0 ! ! define lines ! L,1,2 ! line connecting kpoint 1 and 2 L,1,3 L,2,3 L,2,4

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CBT/Truss/Truss.html


L,3,4 L,3,5 L,4,5 L,4,6 L,5,6 L,5,7 L,6,7 ! ! element definition ! ET,1,LINK1 ! element type #1; spring element R,1,3250 ! real constant #1; Xsect area: 3200 mm^2 MP,EX,1,200e3 ! material property #1; Young's modulus: 200 GPa LESIZE,ALL, , ,1,1,1 ! specify divisions on unmeshed lines LMESH,all ! mesh all lines ! FINISH ! finish pre-processor ! /SOLU ! enter solution phase ! ! apply some constraints DK,1,ALL,0 ! define a DOF constraint at a keypoint DK,7,UY,0 ! ! apply loads ! FK,1,FY,-280e3 ! define a force load to a keypoint FK,3,FY,-210e3 FK,5,FY,-280e3 FK,7,FY,-360e3 ! SOLVE ! solve the resulting system of equations FINISH ! finish solution /POST1 PRRSOL,F ! List Reaction Forces PLDISP,2 ! Plot Deformed shape PLNSOL,U,SUM,0,1 ! Contour Plot of deflection ETABLE,SAXL,LS, 1 ! Axial Stress PRETAB,SAXL ! List Element Table PLETAB,SAXL,NOAV ! Plot Axial Stress

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CBT/Truss/Truss.html


3D Space Frame Example

Problem Description

The problem to be modeled in this example is a simple bicycle frame shown in the following figure. The frame is to be built of hollow aluminum tubing having an outside diameter of 25mm and a wall thickness of 2mm for the main part of the frame. For the rear forks, the tubing will be 12mm outside diameter and 1mm wall thickness.

ANSYS Command Listing ! Command File mode of 3D Bicycle Space Frame /title,3D Bicycle Space Frame /prep7 ! Enter the pre-processor ! Define Some Parameters x1 = 500 ! These parameters are not required; i.e. one could x2 = 825 ! directly enter in the coordinates into the keypoint y1 = 325 ! definition below. y2 = 400 ! However, using parameters makes it very easy to z1 = 50 ! quickly make changes to your model! ! Define Keypoints K,1, 0,y1, 0 ! k,key-point number,x-coord,y-coord,z-coord K,2, 0,y2, 0 K,3,x1,y2, 0 K,4,x1, 0, 0 K,5,x2, 0, z1 K,6,x2, 0,-z1

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CBT/Bike/Print.html


! Define Lines Linking Keypoints L,1,2 ! l,keypoint1,keypoint2 L,2,3 L,3,4 L,4,1 L,4,6 L,4,5 L,3,5 ! these last two line are for the rear forks L,3,6 ! Define Element Type ET,1,pipe16 KEYOPT,1,6,1 ! Define Real Constants ! (Note: the inside diameter must be positive) R,1,25,2 ! r,real set number,outside diameter,wall thickness R,2,12,1 ! second set of real constants - for rear forks ! Define Material Properties MP,EX,1,70000 ! mp,Young's modulus,material number,value MP,PRXY,1,0.33 ! mp,Poisson's ratio,material number,value ! Define the number of elements each line is to be divided into LESIZE,ALL,20 ! lesize,line number(all lines),size of element ! Line Meshing REAL,1 ! turn on real property set #1 LMESH,1,6,1 ! mesh those lines which have that property set ! mesh lines 1 through 6 in steps of 1 REAL,2 ! activate real property set #2 LMESH,7,8 ! mesh the rear forks FINISH ! Finish pre-processing /SOLU ! Enter the solution processor ANTYPE,0 ! Analysis type,static ! Define Displacement Constraints on Keypoints (dk command) DK,1,UX,0,,,UY,UZ ! dk,keypoint,direction,displacement,,,direction,direction DK,5,UY,0,,,UZ DK,6,UY,0,,,UZ ! Define Forces on Keypoints (fk command) FK,3,FY,-600 !fk,keypoint,direction,force FK,4,FY,-200 SOLVE ! Solve the problem FINISH ! Finish the solution processor SAVE ! Save your work to the database



/post1 ! Enter the general post processor /WIND,ALL,OFF /WIND,1,LTOP /WIND,2,RTOP /WIND,3,LBOT /WIND,4,RBOT GPLOT /GCMD,1, PLDISP,2 !Plot the deformed and undeformed edge /GCMD,2, PLNSOL,U,SUM,0,1 ! Set up Element Table information ! Element tables are tables of information regarding the solution data ! You must tell Ansys what pieces of information you want by using the ! etable command: ! etable,arbitrary name,item name,data code number ! The arbitrary name is a name that you give the data in the table ! It serves as a reference name to retrieve the data later ! Use a name that describes the data and is easily remembered. ! The item name and data code number come off of the tables provided. ! Examples: ! For the VonMises (or equivalent) stresses at angle 0 at both ends of the ! element (node i and node j); etable,vonmi0,nmisc,5 etable,vonmj0,nmisc,45 ! For the Axial stresses at angle 0 etable,axii0,ls,1 etable,axij0,ls,33 ! For the Direct axial stress component due to axial load (no bending) ! Note it is independent of angular location. etable,diri,smisc,13 etable,dirj,smisc,15 ! ADD OTHERS THAT YOU NEED IN HERE... ! To plot the data, simply type ! plls, name for node i, name for node j ! for example, /GCMD,3, PLLS,vonmi0,vonmj0 /GCMD,4, PLLS,axii0,axij0 /CONT,2,9,0,,0.27 /CONT,3,9,0,,18 /CONT,4,9,-18,,18



/FOC,ALL,-0.340000,,,1 /replot PRNSOL,DOF,




Introduction This tutorial is the second of three basic tutorials created to illustrate commom features in ANSYS. The plane stress bracket tutorial builds upon techniques covered in the first tutorial (3D Bicycle Space Frame), it is therefore essential that you have completed that tutorial prior to beginning this one.

The 2D Plane Stress Bracket will introduce boolean operations, plane stress, and uniform pressure loading.

Problem Description



ANSYS Command Listing ! Command File mode of 2D Plane Stress Bracket /title, 2D Plane Stress Bracket /prep7 ! Enter the pre-processor ! Create Geometry BLC4,0,0,80,100

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CBT/Bracket/Print.html


CYL4,80,50,50 CYL4,0,20,20 CYL4,0,80,20 BLC4,-20,20,20,60 AADD,ALL ! Boolean Addition - add all of the areas together CYL4,80,50,30 ! Create Bolt Holes CYL4,0,20,10 CYL4,0,80,10 ASBA,6,ALL ! Boolean Subtraction - subtracts all areas (other than 6) from ba ! Define Element Type ET,1,PLANE82 KEYOPT,1,3,3 ! Plane stress element with thickness ! Define Real Constants ! (Note: the inside diameter must be positive) R,1,20 ! r,real set number, plate thickness ! Define Material Properties MP,EX,1,200000 ! mp,Young's modulus,material number,value MP,PRXY,1,0.3 ! mp,Poisson's ratio,material number,value ! Define the number of elements each line is to be divided into AESIZE,ALL,5 ! lesize,all areas,size of element ! Area Meshing AMESH,ALL ! amesh, all areas FINISH ! Finish pre-processing /SOLU ! Enter the solution processor ANTYPE,0 ! Analysis type,static ! Define Displacement Constraints on Lines (dl command) DL, 7, ,ALL,0 ! There is probably a way to do these all at once... DL, 8, ,ALL,0 DL, 9, ,ALL,0 DL,10, ,ALL,0 DL,11, ,ALL,0 DL,12, ,ALL,0 DL,13, ,ALL,0 DL,14, ,ALL,0 ! Define Forces on Keypoints (fk command) FK,9,FY,-1000 !fk,keypoint,direction,force



SOLVE ! Solve the problem FINISH ! Finish the solution processor SAVE ! Save your work to the database /post1 ! Enter the general post processor /WIND,ALL,OFF /WIND,1,LTOP /WIND,2,RTOP /WIND,3,LBOT /WIND,4,RBOT GPLOT /GCMD,1, PLDISP,2 ! Plot the deformed and undeformed edge /GCMD,2, PLNSOL,U,SUM,0,1 ! Plot the deflection USUM /GCMD,3, PLNSOL,S,EQV,0,1 ! Plot the equivalent stress /GCMD,4, PLNSOL,EPTO,EQV,0,1 ! Plot the equivalent strain /CONT,2,10,0,,0.0036 ! Set contour ranges /CONT,3,10,0,,8 /CONT,4,10,0,,0.05e-3 /FOC,ALL,-0.340000,,,1 ! Focus point /replot PRNSOL,DOF, ! Prints the nodal solutions




Introduction This tutorial is the last of three basic tutorials devised to illustrate commom features in ANSYS. Each tutorial builds upon techniques covered in previous tutorials, it is therefore essential that you complete the tutorials in order.

The Solid Modelling Tutorial will introduce various techniques which can be used in ANSYS to create solid models. Filleting, extrusion/sweeping, copying, and working plane orientation will be covered in detail.

Two Solid Models will be created within this tutorial.

We will create a solid model of the pulley shown in the following figure.

We will also create a solid model of the Spindle Base shown in the following figure.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CBT/Solid/Print.html


ANSYS Command Listing Pulley Model

/PREP7 BLC4,2,0,1,5.5 ! Create rectangles BLC4,3,2,5,1 BLC4,8,0,0.5,5 AADD,ALL ! Add the areas together CYL4,3,5.5,0.5 ! Create circles CYL4,8.5,0.2,0.2 ASBA,4,1 ! Subtract an area AGEN,2,2,,,,4.6 ! Mirrors an area AGEN,2,1,,,-0.5 AADD,ALL ! Adds all areas LFILLT,22,7,0.1,, !Create a fillet radius of 0.1mm between lines 30 LFILLT,26,7,0.1,, AL,3,6,9 ! Creates fillet area (arbitrary area using lines AL,10,11,14 AADD,ALL ! Sweep K,1001,0,0,0 ! Keypoints K,1002,0,5,0 VROTAT,3, , , , , ,1001,1002,360, , ! Sweep area 4 about axis formed by keypoints 1001 K,2001,0,3,0 K,2002,1,3,0 K,2003,0,3,1



KWPLAN,1,2001,2002,2003 !Align WorkPlane with keypoints CSYS,5 ! Change Active CS to Global Cartesian Y CYL4,5.5,0,0.5, , , ,1 ! Create circle VGEN,8,5, , , ,45, , ,0 ! Pattern the circle every 45 degrees !Subtract areas vsbv,all,5 vsbv,13,6 vsbv,all,7 vsbv,4,8 vsbv,all,9 vsbv,2,10 vsbv,all,11 vsbv,2,12

Spindle Base Model

/PREP7 BLC4,0,0,109,102 ! Create rectangle K,5,-20,82 ! Keypoints K,6,-20,20 K,7,0,82 K,8,0,20 LARC,4,5,7,20 ! Line arcs LARC,1,6,8,20 L,5,6 AL,4,5,6,7 ! Creates area from 4 lines AADD,1,2 ! Now called area 3 CYL4,0,20,10 ! Area 1 AGEN,2,1, , ,69 ! Mirrors area 1 AGEN,2,1,2, , ,62 ! Mirrors again ASBA,3,ALL ! Subtracts areas VOFFST,6,26 ! Creates volume from area K,100,109,102,0 ! Keypoints K,101,109,2,0 K,102,159,102,sqrt(3)/0.02 KWPLAN,-1,100,101,102 ! Defines working plane BLC4,0,0,102,180 ! Create rectangle CYL4,51,180,51 ! Create circle AADD,25,26 ! Add them together VOFFST,27,26 ! Volume from area VADD,1,2 ! Add volumes AADD,33,34,38 ! Add areas AADD,32,36,37



CYL4,51,180,32, , , ,60 ! Create cylinder VADD,1,3 ! Add volumes CYL4,51,180,18.5, , , ,60 ! Another cylinder VSBV,2,1 ! Subtract it WPCSYS,-1,0 ! This re-aligns the WP with the global coordinate system K,200,-20,61,26 ! Keypoints K,201,0,61,26 K,202,-20,61,30 KWPLAN,-1,200,201,202 ! Shift working plane CSYS,4 ! Change active coordinate system K,203,129-(0.57735*26),0,0 ! Keypoints K,204, 129-(0.57735*26) + 38, sqrt(3)/2*76,0 A,200,203,204 ! Create area from keypoints VOFFST,7,20, ! Volume from area VADD, ALL ! Add it together



Effect of Self Weight on a Cantilever Beam

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to show the required steps to account for the weight of an object in ANSYS.

Loads will not be applied to the beam shown below in order to observe the deflection caused by the weight of the beam itself. The beam is to be made of steel with a modulus of elasticity of 200 GPa.

ANSYS Command Listing /Title, Effects of Self Weight /PREP7 Length = 1000 Width = 50 Height = 10 K,1,0,0 ! Create Keypoints K,2,Length,0 L,1,2 ET,1,BEAM3 ! Set element type R,1,Width*Height,Width*(Height**3)/12,Height !** = exponent MP,EX,1,200000 ! Young's Modulus MP,PRXY,1,0.3 ! Poisson's ratio MP,DENS,1,7.86e-6 ! Density LESIZE,ALL,Length/10, ! Size of line elements LMESH,1 ! Mesh line 1 FINISH /SOLU ! Enter solution mode ANTYPE,0 ! Static analysis

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Density/Print.html


DK,1,ALL,0, ! Constrain keypoint 1 ACEL,,9.8 ! Set gravity constant SOLVE FINISH /POST1 PLDISP,2 ! Display deformed shape

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Density/Print.html


NonLinear Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to outline the steps required to do a simple nonlinear analysis of the beam shown below.

There are several causes for nonlinear behaviour such as Changing Status, Material Nonlinearities and Geometric Nonlinearities (change in response due to large deformations). This tutorial will deal specifically with Geometric Nonlinearities .

To solve this problem, the load will added incrementally. After each increment, the stiffness matrix will be adjusted before increasing the load.

The solution will be compared to the equivalent solution using a linear response.

ANSYS Command Listing /prep7 ! start preprocessor /title,NonLinear Analysis of Cantilever Beam k,1,0,0,0 ! define keypoints k,2,5,0,0 ! 5" beam (length) l,1,2 ! define line et,1,beam3 ! Beam r,1,0.03125,4.069e-5,0.125 ! area, izz, height of beam mp,ex,1,30.0e6 ! Young's Modulus mp,prxy,1,0.3 ! Poisson's ratio esize,0.1 ! element size of 0.1" lmesh,all ! mesh the line finish ! stop preprocessor

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/NonLinear/Print.html


/solu ! start solution phase antype,static ! static analysis nlgeom,on ! turn on non-linear geometry analysis autots,on ! auto time stepping nsubst,5,1000,1 ! Size of first substep=1/5 of the total load, max # substeps=10outres,all,all ! save results of all iterations dk,1,all ! constrain all DOF on ground fk,2,mz,-100 ! applied moment solve /post1 pldisp,1 ! display deformed mesh PRNSOL,U,X ! lists horizontal deflections

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/NonLinear/Print.html


Buckling

Introduction This tutorial was created using ANSYS 7.0 to solve a simple buckling problem.

It is recommended that you complete the NonLinear Tutorial prior to beginning this tutorial

Buckling loads are critical loads where certain types of structures become unstable. Each load has an associated buckled mode shape; this is the shape that the structure assumes in a buckled condition. There are two primary means to perform a buckling analysis:

1. Eigenvalue

Eigenvalue buckling analysis predicts the theoretical buckling strength of an ideal elastic structure. It computes the structural eigenvalues for the given system loading and constraints. This is known as classical Euler buckling analysis. Buckling loads for several configurations are readily available from tabulated solutions. However, in real-life, structural imperfections and nonlinearities prevent most real-world structures from reaching their eigenvalue predicted buckling strength; ie. it over-predicts the expected buckling loads. This method is not recommended for accurate, real-world buckling prediction analysis.

2. Nonlinear

Nonlinear buckling analysis is more accurate than eigenvalue analysis because it employs non-linear, large-deflection, static analysis to predict buckling loads. Its mode of operation is very simple: it gradually increases the applied load until a load level is found whereby the structure becomes unstable (ie. suddenly a very small increase in the load will cause very large deflections). The true non-linear nature of this analysis thus permits the modeling of geometric imperfections, load perterbations, material nonlinearities and gaps. For this type of analysis, note that small off-axis loads are necessary to initiate the desired buckling mode.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Buckling/Print.html


This tutorial will use a steel beam with a 10 mm X 10 mm cross section, rigidly constrained at the bottom. The required load to cause buckling, applied at the top-center of the beam, will be calculated.

ANSYS Command Listing Eigenvalue Buckling

FINISH ! These two commands clear current data /CLEAR /TITLE,Eigenvalue Buckling Analysis /PREP7 ! Enter the preprocessor ET,1,BEAM3 ! Define the element of the beam to be buckled R,1,100,833.333,10 ! Real Consts: type 1, area (mm^2), I (mm^4), height (mm) MP,EX,1,200000 ! Young's modulus (in MPa) MP,PRXY,1,0.3 ! Poisson's ratio K,1,0,0 ! Define the geometry of beam (100 mm high) K,2,0,100 L,1,2 ! Draw the line ESIZE,10 ! Set element size to 1 mm LMESH,ALL,ALL ! Mesh the line FINISH /SOLU ! Enter the solution mode



ANTYPE,STATIC ! Before you can do a buckling analysis, ANSYS ! needs the info from a static analysis PSTRES,ON ! Prestress can be accounted for - required ! during buckling analysis DK,1,ALL ! Constrain the bottom of beam FK,2,FY,-1 ! Load the top vertically with a unit load. ! This is done so the eigenvalue calculated ! will be the actual buckling load, since ! all loads are scaled during the analysis. SOLVE FINISH /SOLU ! Enter the solution mode again to solve buckling ANTYPE,BUCKLE ! Buckling analysis BUCOPT,LANB,1 ! Buckling options - subspace, one mode SOLVE FINISH /SOLU ! Re-enter solution mode to expand info - necessary EXPASS,ON ! An expantion pass will be performed MXPAND,1 ! Specifies the number of modes to expand SOLVE FINISH /POST1 ! Enter post-processor SET,LIST ! List eigenvalue solution - Time/Freq listing is the ! force required for buckling (in N for this case). SET,LAST ! Read in data for the desired mode PLDISP ! Plots the deflected shape

NonLinear Buckling

FINISH ! These two commands clear current data /CLEAR /TITLE, Nonlinear Buckling Analysis /PREP7 ! Enter the preprocessor ET,1,BEAM3 ! Define element as beam3 MP,EX,1,200000 ! Young's modulus (in Pa) MP,PRXY,1,0.3 ! Poisson's ratio R,1,100,833.333,10 ! area, I, height K,1,0,0,0 ! Lower node K,2,0,100,0 ! Upper node (100 mm high) L,1,2 ! Draws line ESIZE,1 ! Sets element size to 1 mm LMESH,ALL ! Mesh line FINISH /SOLU ANTYPE,STATIC ! Static analysis (not buckling) NLGEOM,ON ! Non-linear geometry solution supported OUTRES,ALL,ALL ! Stores bunches of output



NSUBST,20 ! Load broken into 5 load steps NEQIT,1000 ! Use 20 load steps to find solution AUTOTS,ON ! Auto time stepping LNSRCH,ON /ESHAPE,1 ! Plots the beam as a volume rather than line DK,1,ALL,0 ! Constrain bottom FK,2,FY,-50000 ! Apply load slightly greater than predicted ! required buckling load to upper node FK,2,FX,-250 ! Add a horizontal load (0.5% FY) to initiate ! buckling SOLVE FINISH /POST26 ! Time history post processor RFORCE,2,1,F,Y ! Reads force data in variable 2 NSOL,3,2,U,Y ! Reads y-deflection data into var 3 XVAR,2 ! Make variable 2 the x-axis PLVAR,3 ! Plots variable 3 on y-axis /AXLAB,Y,DEFLECTION ! Changes y label /AXLAB,X,LOAD ! Changes X label /REPLOT



Modal Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to outline the steps required to do a simple modal analysis of the cantilever beam shown below.

ANSYS Command Listing FINISH /CLEAR /TITLE, Dynamic Analysis /PREP7 K,1,0,0 ! Enter keypoints K,2,1,0 L,1,2 ! Create line ET,1,BEAM3 ! Element type R,1,0.0001,8.33e-10,0.01 ! Real Const: area,I,height MP,EX,1,2.068e11 ! Young's modulus MP,PRXY,1,0.33 ! Poisson's ratio MP,DENS,1,7830 ! Density LESIZE,ALL,,,10 ! Element size LMESH,1 ! Mesh line

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Modal/Print.html


FINISH /SOLU ANTYPE,2 ! Modal analysis MODOPT,SUBSP,5 ! Subspace, 5 modes EQSLV,FRONT ! Frontal solver MXPAND,5 ! Expand 5 modes DK,1,ALL ! Constrain keypoint one SOLVE FINISH /POST1 ! List solutions SET,LIST SET,FIRST PLDISP ! Display first mode shape ANMODE,10,0.5, ,0 ! Animate mode shape

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Modal/Print.html


Harmonic Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to explain the steps required to perform Harmonic analysis the cantilever beam shown below.

We will now conduct a harmonic forced response test by applying a cyclic load (harmonic) at the end of the beam. The frequency of the load will be varied from 1 - 100 Hz. The figure below depicts the beam with the application of the load.

ANSYS provides 3 methods for conducting a harmonic analysis. These 3 methods are the Full , Reduced and Modal Superposition methods.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Harmonic/Print.html


This example demonstrates the Full method because it is simple and easy to use as compared to the other two methods. However, this method makes use of the full stiffness and mass matrices and thus is the slower and costlier option.

ANSYS Command Listing FINISH /CLEAR /TITLE, Dynamic Analysis /PREP7 K,1,0,0 ! Enter keypoints K,2,1,0 L,1,2 ! Create line ET,1,BEAM3 ! Element type R,1,0.0001,8.33e-10,0.01 ! Real Const: area,I,height MP,EX,1,2.068e11 ! Young's modulus MP,PRXY,1,0.33 ! Poisson's ratio MP,DENS,1,7830 ! Density LESIZE,ALL,,,10 ! Element size LMESH,1 ! Mesh line FINISH /SOLU ANTYPE,3 ! Harmonic analysis DK,1,ALL ! Constrain keypoint 1 FK,2,FY,100 ! Apply force HARFRQ,0,100, ! Frequency range NSUBST,100, ! Number of frequency steps KBC,1 ! Stepped loads SOLVE FINISH /POST26 NSOL,2,2,U,Y, UY_2 ! Get y-deflection data STORE,MERGE PRVAR,2 ! Print data PLVAR,2 ! Plot data

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Harmonic/Print.html


Transient Analysis of a Cantilever Beam

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to show the steps involved to perform a simple transient analysis.

Transient dynamic analysis is a technique used to determine the dynamic response of a structure under a time-varying load.

The time frame for this type of analysis is such that inertia or damping effects of the structure are considered to be important. Cases where such effects play a major role are under step or impulse loading conditions, for example, where there is a sharp load change in a fraction of time.

If inertia effects are negligible for the loading conditions being considered, a static analysis may be used instead.

For our case, we will impact the end of the beam with an impulse force and view the response at the location of impact.

http://www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Transient/Print.html


Since an ideal impulse force excites all modes of a structure, the response of the beam should contain all mode frequencies. However, we cannot produce an ideal impulse force numerically. We have to apply a load over a discrete amount of time dt.

After the application of the load, we track the response of the beam at discrete time points for as long as we like (depending on what it is that we are looking for in the response).

The size of the time step is governed by the maximum mode frequency of the structure we wish to capture. The smaller the time step, the higher the mode frequency we will capture. The rule of thumb in ANSYS is

time_step = 1 / 20f

where f is the highest mode frequency we wish to capture. In other words, we must resolve our step size such that we will have 20 discrete points per period of the highest mode frequency.

It should be noted that a transient analysis is more involved than a static or harmonic analysis. It requires a good understanding of the dynamic behavior of a structure. Therefore, a modal analysis of the structure should be initially performed to provide information about the structure's dynamic behavior.

In ANSYS, transient dynamic analysis can be carried out using 3 methods.



The Full Method: This is the easiest method to use. All types of non-linearities are allowed. It is however very CPU intensive to go this route as full system matrices are used.

The Reduced Method: This method reduces the system matrices to only consider the Master Degrees of Freedom (MDOFs). Because of the reduced size of the matrices, the calculations are much quicker. However, this method handles only linear problems (such as our cantilever case).

The Mode Superposition Method: This method requires a preliminary modal analysis, as factored mode shapes are summed to calculate the structure's response. It is the quickest of the three methods, but it requires a good deal of understanding of the problem at hand.

We will use the Reduced Method for conducting our transient analysis. Usually one need not go further than Reviewing the Reduced Results. However, if stresses and forces are of interest than, we would have to Expand the Reduced Solution.

ANSYS Command Listing finish /clear /TITLE, Dynamic Analysis /FILNAME,Dynamic,0 ! This sets the jobname to 'Dynamic' /PREP7 ! Enter preprocessor K,1,0,0 ! Keypoints K,2,1,0 L,1,2 ! Connect keypoints with line ET,1,BEAM3 ! Element type R,1,0.0001,8.33e-10,0.01 ! Real constants MP,EX,1,2.068e11 ! Young's modulus MP,PRXY,1,0.33 ! Poisson's ratio MP,DENS,1,7830 ! Density LESIZE,ALL,,,10 ! Element size LMESH,1 ! Mesh the line FINISH /SOLU ! Enter solution phase ANTYPE, TRANS ! Transient analysis TRNOPT,REDUC, ! reduced solution method DELTIM,0.001 ! Specifies the time step sizes !At time equals 0s NSEL,S,,,2,11, ! select nodes 2 - 11 M,All,UY, , , ! Define Master DOFs NSEL,ALL ! Reselect all nodes D,1,ALL ! Constrain left end F,2,FY,-100 ! Load right end !*



!At time equals 0.001s TIME,0.001 ! Sets time to 0.001 seconds KBC,0 ! Ramped load step FDELE,2,ALL ! Delete the load at the end !* !At time equals 1s TIME,1 ! Sets time to 1 second KBC,0 ! Ramped load step !* LSSOLVE,1,3,1 ! solve multiple load steps FINISH /POST26 ! Enter time history FILE,'Dynamic','rdsp','.' ! Calls the dynamic file NSOL,2,2,U,Y, UY_2 ! Calls data for UY deflection at node 2 STORE,MERGE ! Stores the data PLVAR,2, ! Plots vs. time !Please note, if you are using a later version of ANSYS, !you will probably have to issue the LSWRITE command at the !end of each load step for the LSSOLVE command to function !properly. In this case, replace the !* found in the code !with LSWRITE and the problem should be solved.



Transient Thermal Conduction Example

Introduction This tutorial was created using ANSYS 7.0 to solve a simple transient conduction problem. Special thanks to Jesse Arnold for the analytical solution shown at the end of the tutorial.

The example is constrained as shown in the following figure. Thermal conductivity (k) of the material is 5 W/m*K and the block is assumed to be infinitely long. Also, the density of the material is 920 kg/m^3 and the specific heat capacity (c) is 2.040 kJ/kg*K.

It is beneficial if the Thermal-Conduction tutorial is completed first to compare with this solution.

ANSYS Command Listing finish /clear /title, Simple Conduction Example /PREP7 ! Enter preprocessor ! define geometry length=1.0 height=1.0 blc4,0,0,length, height ! area - one corner, then width and height

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/TransCond/Print.html


! mesh 2D areas ET,1, PLANE55 ! Thermal element only MP,Dens,1,920 ! Density mp,c,1,2.040 ! Specific heat capacity mp,kxx,1,5 ! Thermal conductivity ESIZE,0.05 ! Element size AMESH,ALL ! Mesh area FINISH /SOLU ANTYPE,4 ! Transient analysis time,300 ! Time at end = 300 nropt,full ! Newton Raphson = full lumpm,0 ! Lumped mass approx off nsubst,20 ! 20 substeps neqit,100 ! Max no. of iterations = 100 autots,off ! Auto time search on lnsrch,on ! Line search on outres,all,all ! Output data for all substeps kbc,1 ! fixed temp BC's NSEL,S,LOC,Y,height ! select nodes on top with y=height D,ALL,TEMP,500 ! apply fixed temp of 500K NSEL,ALL NSEL,s,LOC,Y,0 D,ALL,TEMP,100 ! apply fixed temp of 100K NSEL,ALL IC,all,Temp,100 ! Initial Conditions: 100K SOLVE FINISH /POST1 ! Enter postprocessor /CONT,1,8,100,,500 ! Define a contour range PLNSOL,TEMP ! Plot temperature contour ANTIME,20,0.5,,0,2,0,500 ! Animate temp over time

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/TransCond/Print.html


Modelling Using Axisymmetry

Introduction This tutorial was completed using ANSYS 7.0 This tutorial is intended to outline the steps required to create an axisymmetric model.

The model will be that of a closed tube made from steel. Point loads will be applied at the center of the top and bottom plate to make an analytical verification simple to calculate. A 3/4 cross section view of the tube is shown below.

As a warning, point loads will create discontinuities in the your model near the point of application. If you chose to use these types of loads in your own modelling, be very careful and be sure to understand the theory of how the FEA package is appling the load and the assumption it is making. In this case, we will only be concerned about the stress distribution far from the point of application, so the discontinuities will have a negligable effect.

ANSYS Command Listing finish /clear /title, Axisymmetric Tube

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Axisymmetric/Print....


/prep7 /triad,off ! Turns off origin triad marker rectng,0,20,0,5 ! Create 3 overlapping rectangles rectng,15,20,0,100 rectng,0,20,95,100 aadd,all ! Add the areas together et,1,plane2 ! Define element type keyopt,1,3,1 ! Turns on axisymmetry mp,ex,1,200000 ! Young's Modulus mp,prxy,1,0.3 ! Poisson's ratio esize,2 ! Mesh size amesh,all ! Mesh the area finish /solu antype,0 ! Static analysis lsel,s,loc,x,0 ! Select the lines at x=0 dl,all,,symm ! Symmetry constraints lsel,all ! Re-select all lines nsel,s,loc,y,50 ! Node select at y=50 d,all,uy,0 ! Constrain motion in y nsel,all ! Re-select all nodes fk,1,fy,-100 ! Apply point loads in center fk,12,fy,100 solve finish /post1 nsel,s,loc,y,45,55 ! Select nodes from y=45 to y=55 prnsol,s,comp ! List stresses on those nodes nsel,all ! Re-select all nodes /expand,27,axis,,,10 ! Expand the axisymmetric elements /view,1,1,2,3 ! Change the viewing angle /replot

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CIT/Axisymmetric/Print....


Application of Joints and Springs in ANSYS

Introduction This tutorial was created using ANSYS 5.7.1. This tutorial will introduce:

the use of multiple elements in ANSYS elements COMBIN7 (Joints) and COMBIN14 (Springs) obtaining/storing scalar information and store them as parameters.

A 1000N vertical load will be applied to a catapult as shown in the figure below. The catapult is built from steel tubing with an outer diameter of 40 mm, a wall thickness of 10, and a modulus of elasticity of 200GPa. The springs have a stiffness of 5 N/mm.

ANSYS Command Listing /title, Catapult /PREP7 ET,1,PIPE16 ! Element type 1 ET,2,COMBIN7 ! Element type 2 ET,3,COMBIN14 ! Element type 3 R,1,40,10 ! Real constants 1

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CAT/Joints/Print.html


R,2,1e9,1e9,1e9 ! Real constants 2 R,3,5, , , ! Real constants 3 MP,EX,1,200000 ! Young's modulus (Material 1) MP,PRXY,1,0.33 ! Poisson's ratio (Material 1) N, 1, 0, 0, 0 ! Node locations N, 2, 0, 0,1000 N, 3,1000, 0,1000 N, 4,1000, 0, 0 N, 5, 0,1000,1000 N, 6, 0,1000, 0 N, 7, 700, 700, 500 N, 8, 400, 400, 500 N, 9, 0, 0, 0 N,10, 0, 0,1000 N,11, 0, 0, 500 N,12, 0, 0,1500 N,13, 0, 0,-500 TYPE,1 ! Turn on Element 1 REAL,1 ! Turn on Real constants 1 MAT,1 ! Turn on Material 1 E, 1, 6 ! Element connectivity E, 2, 5 E, 1, 4 E, 2, 3 E, 3, 4 E,10, 8 E, 9, 8 E, 7, 8 E,12, 5 E,13, 6 E,12,13 E, 5, 3 E, 6, 4 TYPE,2 ! Turn on Element 2 REAL,2 ! Turn on Real constants 2 E, 1, 9, 11 ! Element connectivity E, 2, 10, 11 TYPE,3 ! Turn on Element 3 REAL,3 ! Turn on Real constants 3 E,5,8 ! Element connectivity E,8,6 /PNUM,KP,0 ! Number nodes /PNUM,ELEM,1 ! Number elements /REPLOT FINISH /SOLU ! Enter solution phase ANTYPE,0 ! Static analysis NLGEOM,ON ! Non-linear geometry on



NSUBST,5 ! 5 Load steps of equal size D,3,ALL,0,,,4,12,13 ! Constrain nodes 3,4,12,13 F,7,FY,-1000 ! Load node 7 SOLVE FINISH /POST1 PLDISP,2 *GET,VERT7,NODE,7,U,Y



Design Optimization

Introduction This tutorial was completed using ANSYS 7.0 The purpose of this tutorial is to introduce a method of solving design optimization problems using ANSYS. This will involve creating the geometry utilizing parameters for all the variables, deciding which variables to use as design, state and objective variables and setting the correct tolerances for the problem to obtain an accurately converged solution in a minimal amount of time. The use of hardpoints to apply forces/constraints in the middle of lines will also be covered in this tutorial.

A beam has a force of 1000N applied as shown below. The purpose of this optimization problem is to minimize the weight of the beam without exceeding the allowable stress. It is necessary to find the cross sectional dimensions of the beam in order to minimize the weight of the beam. However, the width and height of the beam cannot be smaller than 10mm. The maximum stress anywhere in the beam cannot exceed 200 MPa. The beam is to be made of steel with a modulus of elasticity of 200 GPa.

ANSYS Command Listing /prep7 /title, Design Optimization *set,H,20 ! Set an initial height of 20 mm *set,W,20 ! Set an initial width of 20 mm K,1,0,0 ! Keypoint locations K,2,1000,0 L,1,2 ! Create line HPTCREATE,LINE,1,0,RATI,.75, ! Create hardpoint 75% from left side ET,1,BEAM3 ! Element type R,1,W*H,(W*H**3)/12,H,,,, ! Real consts: area,I (note '**', not '^'),heightMP,EX,1,200000 ! Young's modulus MP,PRXY,1,0.3 ! Poisson's ratio

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CAT/Optimization/Print....


ESIZE,100 ! Mesh size LMESH,ALL ! Mesh line FINISH /SOLU ANTYPE,0 ! Static analysis DK,1,UX,0 ! Pin keypoint 1 DK,1,UY,0 DK,2,UY,0 ! Support keypoint 2 FK,3,FY,-2000 ! Force at hardpoint SOLVE FINISH /POST1 ETABLE,EVolume,VOLU, ! Volume of single element SSUM ! Sum all volumes *GET,Volume,SSUM,,ITEM,EVOLUME ! Create parameter 'Volume' for volume of beam ETABLE,SMAX_I,NMISC,1 ! Create parameter 'SMaxI' for max stress at I nodESORT,ETAB,SMAX_I,0,1,, *GET,SMAXI,SORT,,MAX ETABLE,SMAX_J,NMISC,3 ! Create parameter 'SMaxJ' for max stress at J nodESORT,ETAB,SMAX_J,0,1,, *GET,SMAXJ,SORT,,MAX *SET,SMAX,SMAXI>SMAXJ ! Create parameter 'SMax' as max stress LGWRITE,optimize,txt,C:\TEMP ! Save logfile to C:\Temp\optimize.txt /OPT OPANL,'optimize','txt','C:\Temp\' ! Assign optimize.txt as analysis file OPVAR,H,DV,10,50,0.001 ! Height design variable, min 10 mm, max 50 mm, toOPVAR,W,DV,10,50,0.001 ! Width design variable, min 10 mm, max 50 mm, tolOPVAR,SMAX,SV,195,200,0.001 ! Height state variable, min 195 MPa, max 200 MPa,OPVAR,VOLUME,OBJ,,,200 ! Volume as object variable, tolerance 200 mm^2 OPTYPE,FIRS ! First-order analysis OPFRST,30,100,0.2, ! Max iteration, Percent step size, Percent forwarOPEXE ! Run optimization PLVAROPT,H,W ! Graph optimation data /AXLAB,X,Number of Iterations /AXLAB,Y,Width and Height (mm) /REPLOT

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CAT/Optimization/Print....


Substructuring

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to show the how to use substructuring in ANSYS. Substructuring is a procedure that condenses a group of finite elements into one super-element. This reduces the required computation time and also allows the solution of very large problems.

A simple example will be demonstrated to explain the steps required, however, please note that this model is not one which requires the use of substructuring. The example involves a block of wood (E =10 GPa v =0.29) connected to a block of silicone (E = 2.5 MPa, v = 0.41) which is rigidly attached to the ground. A force will be applied to the structure as shown in the following figure. For this example, substructuring will be used for the wood block.

The use of substructuring in ANSYS is a three stage process:

1. Generation Pass Generate the super-element by condensing several elements together. Select the degrees of freedom to save (master DOFs) and to discard (slave DOFs). Apply loads to the super-element

2. Use Pass Create the full model including the super-element created in the generation pass. Apply remaining loads to the model. The solution will consist of the reduced solution tor the super-element and the complete solution for the non-superelements.

3. Expansion Pass Expand the reduced solution to obtain the solution at all DOFs for the super-element.

Note that a this method is a bottom-up substructuring (each super-element is created separately and then assembled in the Use Pass). Top-down substructuring is also possible in ANSYS (the entire model is built, then

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CAT/Substructuring/Prin...


super-element are created by selecting the appropriate elements). This method is suitable for smaller models and has the advantage that the results for multiple super-elements can be assembled in postprocessing.

ANSYS Command Listing ! Bottom-Up Substructuring ! GENERATION PASS - Build the superelement portion of the model FINISH /CLEAR, START /FILNAME,GEN ! Change jobname /PREP7 ! Create Geometry blc4,0,40,100,100 ! Creates rectangle ! Define material properties of wood section ET,1,PLANE42 ! Element type MP,EX,1, 10000 ! Young's Modulus MP,PRXY,1,0.29 ! Poisson's ratio ! meshing AESIZE,1,10, ! Element size amesh,1 ! Mesh area FINISH /SOLU ANTYPE,SUBST ! SUBSTRUCTURE GENERATION PASS SEOPT,GEN,,2 ! Name = GEN and no printed output NSEL,S,EXT ! Select all external nodes M,ALL,ALL ! Make all selected nodes master DOF's NSEL,ALL ! Reselect all nodes NSEL,S,LOC,Y,140 ! Select the corner node NSEL,R,LOC,X,0 F,ALL,FX,5 ! Load it NSEL,ALL ! Reselect all nodes SAVE ! Saves file to jobname.db SOLVE ! GEN.SUB created FINISH ! USE PASS FINISH /CLEAR /FILNAME,USE ! Change jobname to use /PREP7 ! Create Geometry of non superelements blc4,0,0,100,40 ! Creates rectangle ! Define material properties ET,2,PLANE42 ! Element type TYPE,2 ! Turns on element type 2



MP,EX,2, 2.5 ! Second material property set for silicon MP,PRXY,2,0.41 ! Meshing AESIZE,1,10, ! Element size mat,2 ! Turns on Material 2 real,2 ! Turns on real constants 2 amesh,1 ! Mesh the area ! Superelement ET,1,MATRIX50 ! MATRIX50 is the superelement type TYPE,1 ! Turns on element type 1 *GET,MaxNode,NODE,,NUM,MAX ! determine the max number of nodes SETRAN,GEN,,MaxNode,GEN2 ! node number offset SE,GEN2 ! Read in superelement matrix NSEL,S,LOC,Y,40 ! Select nodes at interface CPINTF,ALL ! Couple node pairs at interface NSEL,ALL FINISH /SOLU ANTYPE,STATIC ! Static analysis NSEL,S,LOC,Y,0 ! Select all nodes at y = 0 D,ALL,ALL,0 ! Constrain those nodes NSEL,ALL ! Reselect all nodes ESEL,S,TYPE,,1 ! Element select SFE,ALL,1,SELV,,1 ! Apply super-element load vector ESEL,ALL ! Reselect all elements SAVE SOLVE FINISH /POST1 ! Enter post processing PLNSOL,U,SUM,0,1 ! Plot deflection contour FINISH ! EXPANSION PASS /CLEAR ! Clear database /FILNAME,GEN ! Change jobname back to generation pass jobname RESUME ! Restore generation pass database /SOLU ! Enter SOLUTION EXPASS,ON,YES ! Activate expansion pass SEEXP,GEN2,USE ! Superelement name to be expanded EXPSOL,1,1, ! Expansion pass info SOLVE ! Initiate expansion pass solution. Full superelement solFINISH /POST1 PLNSOL,U,SUM,0,1 ! Plot deflection contour



Coupled Structural/Thermal Analysis

Introduction This tutorial was completed using ANSYS 7.0 The purpose of this tutorial is to outline a simple coupled thermal/structural analysis. A steel link, with no internal stresses, is pinned between two solid structures at a reference temperature of 0 C (273 K). One of the solid structures is heated to a temperature of 75 C (348 K). As heat is transferred from the solid structure into the link, the link will attemp to expand. However, since it is pinned this cannot occur and as such, stress is created in the link. A steady-state solution of the resulting stress will be found to simplify the analysis.

Loads will not be applied to the link, only a temperature change of 75 degrees Celsius. The link is steel with a modulus of elasticity of 200 GPa, a thermal conductivity of 60.5 W/m*K and a thermal expansion coefficient of 12e-6 /K.

Preprocessing: Defining the Problem According to Chapter 2 of the ANSYS Coupled-Field Guide, "A sequentially coupled physics analysis is the combination of analyses from different engineering disciplines which interact to solve a global engineering problem. For convenience, ...the solutions and procedures associated with a particular engineering discipline [will be referred to as] a physics analysis. When the input of one physics analysis depends on the results from another analysis, the analyses are coupled."

Thus, each different physics environment must be constructed seperately so they can be used to determine the coupled physics solution. However, it is important to note that a single set of nodes will exist for the entire model. By creating the geometry in the first physical environment, and using it with any following coupled environments, the geometry is kept constant. For our case, we will create the geometry in the Thermal Environment, where the thermal effects will be applied.

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CAT/Coupled/Print.html


Although the geometry must remain constant, the element types can change. For instance, thermal elements are required for a thermal analysis while structural elements are required to deterime the stress in the link. It is important to note, however that only certain combinations of elements can be used for a coupled physics analysis. For a listing, see Chapter 2 of the ANSYS Coupled-Field Guide located in the help file.

The process requires the user to create all the necessary environments, which are basically the preprocessing portions for each environment, and write them to memory. Then in the solution phase they can be combined to solve the coupled analysis.

ANSYS Command Listing finish /clear /title, Thermal Stress Example /prep7 ! Enter preprocessor k,1,0,0 ! Keypoints k,2,1,0 l,1,2 ! Line connecting keypoints et,1,link33 ! Element type r,1,4e-4, ! Area mp,kxx,1,60.5 ! Thermal conductivity esize,0.1 ! Element size lmesh,all ! Mesh line physics,write,thermal ! Write physics environment as thermal physics,clear ! Clear the environment etchg,tts ! Element type mp,ex,1,200e9 ! Young's modulus mp,prxy,1,0.3 ! Poisson's ratio mp,alpx,1,12e-6 ! Expansion coefficient physics,write,struct ! Write physics environment as struct physics,clear finish /solu ! Enter the solution phase antype,0 ! Static analysis physics,read,thermal ! Read in the thermal environment dk,1,temp,348 ! Apply a temp of 75 to keypoint 1 solve finish /solu ! Re-enter the solution phase physics,read,struct ! Read in the struct environment ldread,temp,,,,,,rth ! Apply loads derived from thermal environment tref,273 dk,1,all,0 ! Apply structural constraints dk,2,UX,0



solve finish /post1 ! Enter postprocessor etable,CompStress,LS,1 ! Create an element table for link stress PRETAB,CompStress ! Print the element table



Using P-Elements



ANSYS Command Listing finish /clear /title, P-Method Meshing /pmeth,on ! Initialize p-method in ANSYS

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CAT/PElement/Print.html


/prep7 ! Enter preprocessor k,1,0,0 ! Keypoints defining geometry k,2,0,100 k,3,20,100 k,4,45,52 k,5,55,52 k,6,80,100 k,7,100,100 k,8,100,0 k,9,80,0 k,10,55,48 k,11,45,48 k,12,20,0 a,1,2,3,4,5,6,7,8,9,10,11,12 ! Create area from keypoints et,1,plane145 ! Element type keyopt,1,3,3 ! Plane stress with thickness option r,1,10 ! Real constant - thickness mp,ex,1,200000 ! Young's modulus mp,prxy,1,0.3 ! Poisson's ratio esize,5 ! Element size amesh,all ! Mesh area finish /solu ! Enter solution phase antype,0 ! Static analysis nsubst,20,100,20 ! Number of substeps outres,all,all ! Output data for all substeps time,1 ! Time at end = 1 lsel,s,loc,x,0 ! Line select at x=0 dl,all,,all ! Constrain the line, all DOF's lsel,all ! Re-select all lines lsel,s,loc,x,100 ! Line select at x=100 sfl,all,pres,-100 ! Apply a pressure lsel,all ! Re-select all lines solve finish /post1 ! Enter postprocessor set,last ! Select last set of data plesol,s,eqv ! Plot the equivalent stress

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CAT/PElement/Print.html


Using P-Elements



ANSYS Command Listing finish /clear /title, Convection Example /prep7 ! Enter the preprocessor ! define geometry k,1,0,0 ! Define keypoints k,2,0.03,0 k,3,0.03,0.03 k,4,0,0.03 a,1,2,3,4 ! Connect the keypoints to form area



! mesh 2D areas ET,1,Plane55 ! Element type MP,Dens,1,920 ! Define density mp,c,1,2040 ! Define specific heat mp,kxx,1,1.8 ! Define heat transfer coefficient esize,0.0005 ! Mesh size amesh,all ! Mesh area finish /solu ! Enter solution phase antype,4 ! Transient analysis time,60 ! Time at end of analysis nropt,full ! Newton Raphson - full lumpm,0 ! Lumped mass off nsubst,20 ! Number of substeps, 20 neqit,100 ! Max no. of iterations autots,off ! Auto time search off lnsrch,on ! Line search on outres,all,all ! Output data for all substeps kbc,1 ! Load applied in steps, not ramped IC,all,temp,268 ! Initial conditions, temp = 268 nsel,s,ext ! Node select all exterior nodes sf,all,conv,10,368 ! Apply a convection BC nsel,all ! Reselect all nodes /gst,off ! Turn off graphical convergence monitor solve finish /post1 ! Enter postprocessor set,last ! Read in last subset of data etable,melty,temp, ! Create an element table esel,s,etab,melty,273 ! Select all elements from table above 273 finish /solu ! Re-enter solution phase antype,,rest ! Restart analysis ekill,all ! Kill all selected elements esel,all ! Re-select all elements finish /post1 ! Re-enter postprocessor set,last ! Read in last subset of data esel,s,live ! Select all live elements plnsol,temp ! Plot the temp contour of the live elements



Contact Elements

Introduction This tutorial was completed using ANSYS 7.0 The purpose of the tutorial is to describe how to utilize contact elements to simulate how two beams react when they come into contact with each other.

The beams, as shown below, are 100mm long, 10mm x 10mm in cross-section, have a Young's modulus of 200 GPa, and are rigidly constrained at the outer ends. A 10KN load is applied to the center of the upper, causing it to bend and contact the lower.

ANSYS Command Listing finish /clear /title,Contact Elements /prep7 ! Top Beam X1=0 Y1=15 L1=100 H1=10 ! Bottom Beam X2=50 Y2=0 L2=100 H2=10 ! Create Geometry blc4,X1,Y1,L1,H1 blc4,X2,Y2,L2,H2

http://www.mece.ualberta.ca/tutorials/ansys/CL/CAT/contact/print.html


! define element type ET,1,plane42 ! element type 1 keyopt,1,3,3 ! plane stress w/thick type,1 ! activate element type 1 R, 1, 10 ! thickness 0.01 ! define material properties MP,EX, 1, 200e3 ! Young's modulus MP,NUXY,1, 0.3 ! Poisson's ratio ! meshing esize,2 ! set meshing size amesh,all ! mesh area 1 ET,2,contac48 ! defines second element type - 2D contact elements keyo,2,7,1 ! contact time/load prediction r,2,200000,,,,10 TYPE,2 ! activates or sets this element type real,2 ! activates or sets the real constants ! define contact nodes and elements ! first the contact nodes asel,s,area,,1 ! select top area nsla,s,1 ! select the nodes within this area nsel,r,loc,y,Y1 ! select bottom layer of nodes in this area nsel,r,loc,x,X2,(X2+L2/2)! select the nodes above the other beam cm,source,node ! call this group of nodes 'source' ! then the target nodes allsel ! relect everything asel,s,area,,2 ! select bottom area nsla,s,1 ! select nodes in this area nsel,r,loc,y,H2 ! select bottom layer of nodes in this area nsel,r,loc,x,X2,(X2+L2/2)! select the nodes above the other beam cm,target,node ! call this selection 'target' gcgen,source,target,3 ! generate contact elements between defined nodes finish /solut antype,0 time,1 ! Sets time at end of run to 1 sec autots,on ! Auto time-stepping on nsubst,100,1000,20 ! Number of sub-steps outres,all,all ! Write all output neqit,100 ! Max number of iterations nsel,s,loc,x,X1 ! Constrain top beam nsel,r,loc,y,Y1,(Y1+H1) d,all,all nsel,all nsel,s,loc,x,(X2+L2) ! Constrain bottom beam



nsel,r,loc,y,Y2,(Y2+H2) d,all,all nsel,all nsel,s,loc,x,(L1/2+X1) ! Apply load nsel,r,loc,y,(Y1+H1) f,all,fy,-10000 nsel,all solve finish /post1 /dscale,1,1 /CVAL,1,20,40,80,160,320,640,1280,2560 PLNSOL,S,EQV,0,1



ANSYS Parametric Design Language (APDL)

Introduction This tutorial was completed using ANSYS 7.0 The purpose of this tutorial is to familiarize the user with the ANSYS Parametric Design Language (APDL). This will be a very basic introduction to APDL, covering things like variable definition and simple looping. Users familiar with basic programming languages will probably find the APDL very easy to use. To learn more about APDL and see more complex examples, please see the APDL Programmer's Guide located in the help file.

This tutorial will cover the preprocessing stage of constructing a truss geometry. Variables including length, height and number of divisions of the truss will be requested and the APDL code will construct the geometry.

ANSYS Command Listing finish /clear /prep7 *ask,LENGTH,How long is the truss,100 *ask,HEIGHT,How tall is the truss,20 *ask,DIVISION,How many cross supports even number,2 DELTA_L = (LENGTH/(DIVISION/2))/2 NUM_K = DIVISION + 1 COUNT = -1 X_COORD = 0 *do,i,1,NUM_K,1 COUNT = COUNT + 1

http://www.mece.ualberta.ca/tutorials/ansys/cl/cat/apdl/apdl.html


OSCILATE = (-1)**COUNT X_COORD = X_COORD + DELTA_L *if,OSCILATE,GT,0,THEN k,i,X_COORD,0 *else k,i,X_COORD,HEIGHT *endif *enddo KEYP = 0 *do,j,1,DIVISION,1 KEYP = KEYP + 1 L,KEYP,(KEYP+1) *if,KEYP,LE,(DIVISION-1),THEN L,KEYP,(KEYP+2) *endif *enddo et,1,link1 r,1,100 mp,ex,1,200000 mp,prxy,1,0.3 esize,,1 lmesh,all finish

http://www.mece.ualberta.ca/tutorials/ansys/cl/cat/apdl/apdl.html



Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to outline the steps required to view cross sectional results (Deformation, Stress, etc.) of the following example.

ANSYS Command Listing FINISH /CLEAR /Title, Cross-Sectional Results of a Simple Cantilever Beam /PREP7 ! All dims in mm Width = 60 Height = 40 Length = 400 BLC4,0,0,Width,Height,Length ! Creates a rectangle /ANGLE, 1 ,60.000000,YS,1 ! Rotates the display /REPLOT,FAST ! Fast redisplay ET,1,SOLID45 ! Element type MP,EX,1,200000 ! Young's Modulus MP,PRXY,1,0.3 ! Poisson's ratio esize,20 ! Element size vmesh,all ! Mesh the volume

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CPP/Slice/Print.html


FINISH /SOLU ! Enter solution mode ANTYPE,0 ! Static analysis ASEL,S,LOC,Z,0 ! Area select at z=0 DA,All,ALL,0 ! Constrain the area ASEL,ALL ! Reselect all areas KSEL,S,LOC,Z,Length ! Select certain keypoint KSEL,R,LOC,Y,Height KSEL,R,LOC,X,Width FK,All,FY,-2500 ! Force on keypoint KSEL,ALL ! Reselect all keypoints SOLVE ! Solve FINISH /POST1 ! Enter post processor PLNSOL,U,SUM,0,1 ! Plot deflection WPOFFS,Width/2,0,0 ! Offset the working plane for cross-section view WPROTA,0,0,90 ! Rotate working plane /CPLANE,1 ! Cutting plane defined to use the WP /TYPE,1,8 ! QSLICE display WPCSYS,-1,0 ! Deflines working plane location WPOFFS,0,0,1/16*Length ! Offset the working plane /CPLANE,1 ! Cutting plane defined to use the WP /TYPE,1,5 ! Use the capped hidden display PLNSOL,S,EQV,0,1 ! Plot equivalent stress !Animation ANCUT,43,0.1,5,0.05,0,0.1,7,14,2 ! Animate the slices

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CPP/Slice/Print.html


Advanced X-Sectional Results: Using Paths to Post Process Results

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to create and use 'paths' to provide extra detail during post processing. For example, one may want to determine the effects of stress concentrators along a certain path. Rather than plotting the entire contour plot, a plot of the stress along that path can be made.

In this tutorial, a steel plate measuring 100 mm X 200 mm X 10 mm will be used. Three holes are drilled through the vertical centerline of the plate. The plate is constrained in the y-direction at the bottom and a uniform, distributed load is pulling on the top of the plate.

ANSYS Command Listing finish /clear /title, Defining Paths /PREP7 ! create geometry BLC4,0,0,200,100

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CPP/AdvancedX-SecRes...


cyl4,50,50,10 cyl4,100,50,10 cyl4,150,50,10 asba,1,all et,1,plane2,,,3 ! Plane element R,1,10 ! thickness of plane mp,ex,1,200000 ! Young's Modulus mp,prxy,1,0.3 ! Poisson's ratio esize,5 ! mesh size amesh,all ! area mesh finish /solu ! apply constraints lsel,s,loc,y,0 ! select line for contraint application dl,all,,UY ! constrain all DOF's on this face allsel ! apply loads allsel ! restore entire selection lsel,s,loc,y,100 SFL,all,PRES,-2000/10 ! apply a pressure load on a line allsel solve ! solve resulting system of equations finish ! plot results /window,1,top ! define a window (top half of screen) /POST1 PLNSOL,S,eqv,2,1 ! plot stress in xx direction (deformed and undeformed edge) /window,1,off /noerase /window,2,bot ! define a window (bottom half of screen) nsel,all ! define nodes to define path nsel,s,loc,y,50 ! choose nodes half way through structure path,cutline,2,,1000 ! define a path labeled cutline ppath,1,,0,50 ! define endpoint nodes on path ppath,2,,200,50 PDEF,,S,eqv,AVG ! calculate equivalent stress on path nsel,all PLPAGM,SEQV,200,NODE ! show graph on plot with nodes

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CPP/AdvancedX-SecRes...


Data Plotting: Using Tables to Post Process Results

Introduction This tutorial was created using ANSYS 7.0 The purpose of this tutorial is to outline the steps required to plot Vertical Deflection vs. Length of the following beam using tables, a special type of array. By plotting this data on a curve, rather than using a contour plot, finer resolution can be achieved.

This tutorial will use a steel beam 400 mm long, with a 40 mm X 60 mm cross section as shown above. It will be rigidly constrained at one end and a -2500 N load will be applied to the other.

ANSYS Command Listing finish /clear /title, Use of Tables for Data Plots /prep7 elementsize = 20 length = 400 et,1,beam3 ! Beam3 element r,1,2400,320e3,40 ! Area,I,Height mp,ex,1,200000 ! Youngs Modulus mp,prxy,1,0.3 ! Poisson's Ratio k,1,0,0 ! Geometry k,2,length,0 l,1,2 esize,elementsize ! Mesh size

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CPP/DataPlotting/Print.h...


lmesh,all ! Mesh finish /solu antype,static ! Static analysis dk,1,all ! Constrain one end fully fk,2,fy,-2500 ! Apply load to other end solve finish /post1 ! Note, there are 21 nodes in the mesh. For the procedure below ! the table must have (#nodes + 1) rows rows = ((length/elementsize + 1) + 1) *DIM,graph,TABLE,rows,2,1 ! Creat a table called "graph" ! 22 rows x 2 columns x 1 plane *vget,graph(1,1),node,all,loc,x ! Put node locations in the x direction ! in the first column for all nodes *vget,graph(1,2),node,all,u,y ! Put node deflections in the y direction ! in the second column *set,graph(2,1),0 ! Delete data in (2,1) which is for x = 400 ! otherwise graph is not plotted properly *set,graph(2,2),0 ! Delete data in (2,2) which is for UY @ x = 400 ! otherwise graph is not plotted properly *vget,graph(rows,1),node,2,loc,x ! Re-enter the data for x = 400, but at the end *vget,graph(rows,2),node,2,u,y ! of the table *vplot,graph(1,1),graph(1,2) ! Plot the data in the table /axlab,x,Length ! Change the axis labels /axlab,y,Vertical Deflection /replot

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/CPP/DataPlotting/Print.h...


Radiation Example

Problem Description

Radiation heat transfer between concentric cylinders will be modeled in this example. This is a general version of one of the verification examples converted to metric units.

ANSYS Command Listing /PREP7 /TITLE, RADIATION HEAT TRANSFER BETWEEN CONCENTRIC CYLINDERS ANTYPE,STATIC ! this is a general version of VM125 converted to metric rin=2*0.0254 ! inches to metres rout=8*0.0254 ndiv=20 arc=360 emis1=0.7 emis2=0.5 T1=700 ! degrees C T2=400 offset=273 ! to convert to degrees K stefbolt=5.699*10**(-8) ! metric version k,1,0,0 ! center of tube 1 k,5,0,0 ! center of retort k,6,0,0,-1 k,7,1 k,8,0,0,1 circle,1,rin,6,7,arc,ndiv ! inner cylinder, generated clockwise CIRCLE,5,rout,8,7,arc,ndiv ! outer cylinder; generated counter-clockwise ET,1,LINK32,,,,,,,1 ! HEAT CONDUCTING BAR; SUPPRESS SOLUTION OUTPUT R,1,1 ! UNIT CROSS-SECTIONAL AREA (ARBITRARY) MP,KXX,1,1 ! CONDUCTIVITY of inner cylinder (arbitrary) MAT,1 ESIZE,,1 csys,1 ! cylindrical coord system lsel,s,loc,x,rin LMESH,ALL lsel,all MP,KXX,2,1 ! CONDUCTIVITY of outer cylinder (arbitrary) MAT,2 lsel,s,loc,x,rout LMESH,all lsel,all csys,0 ! reset to rect coord system

University of Alberta ANSYS Tutorials - www.mece.ualberta.ca/tutorials/ansys/CL/Radiation/Print.html


FINISH /AUX12 EMIS,1,emis1 EMIS,2,emis2 VTYPE,0 ! HIDDEN PROCEDURE FOR VIEW FACTORS GEOM,1 ! GEOMETRY SPECIFICATION 2-D STEF,stefbolt ! Stefan-Boltzmann constant WRITE,VM125 ! WRITE RADIATION MATRIX TO FILE VM125.SUB FINISH /PREP7 DOF,TEMP ET,2,MATRIX50,1,,,,,1 ! SUPERELEMENT (RADIATION MATRIX) TYPE,2 SE,VM125 ! defines superelement and where its written to TOFFST,offset ! TEMPERATURE OFFSET FOR ABSOLUTE SCALE csys,1 nsel,s,loc,x,rout ! SELECT OUTER CYLINDER NODES D,ALL,TEMP,T1 ! T1 = 273 + 700 DEG. K nsel,all nsel,s,loc,x,rin ! SELECT INNER CYLINDER NODES D,ALL,TEMP,T2 ! T2 = 273 + 400 DEG. K nsel,all csys,0 FINISH /SOLU SOLVE FINISH /POST1 csys,1 nsel,s,loc,x,rin ! SELECT INNER CYLINDER NODES /com /COM,:) :) heat flow from inner to outer :) :) /com PRRSOL ! PRINT HEAT FLOW FROM INNER TO OUTER CYLINDER nsel,all nsel,s,loc,x,rout ! select outer cylinder nodes /com /COM,:) :) heat flow from outer to inner :) :) /com PRRSOL ! PRINT HEAT FLOW FROM OUTER TO INNER CYLINDER FSUM,HEAT ! only from selected nodes !!! nsel,all *GET,Q,FSUM,0,ITEM,HEAT *DIM,LABEL,CHAR,1,2 *DIM,VALUE,,1,3 LABEL(1,1) = 'Q(W/m) ' ! the 1 below is for unit length numer=stefbolt*2*pi*rin*1*((offset+T1)**4-(offset+T2)**4) exact=numer/(1/emis1+(rin/rout)*(1/emis2-1)) *VFILL,VALUE(1,1),DATA,exact *VFILL,VALUE(1,2),DATA,Q *VFILL,VALUE(1,3),DATA,ABS(Q/exact) /COM



/COM,--------------- VM125 RESULTS COMPARISON -------------- /COM, /COM, | TARGET | ANSYS | RATIO /COM, *VWRITE,LABEL(1,1),VALUE(1,1),VALUE(1,2),VALUE(1,3) (1X,A8,' ',F10.1,' ',F10.1,' ',1F5.3) /COM,------------------------------------------------------- /COM, FINISH



Documents

Tutorial Completo Ansys