[PPT]Interfacing with ANSYS - Lawrence Berkeley National …als/FEA/ANSYS_V9_INFO/Workbench... · Web viewChapter 5 Accessing ANSYS Options Chapter Overview In this chapter, the following

Accessing ANSYS Options

Chapter 5

February 4, 2005Inventory

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Chapter Overview• In this chapter, the following ways of interfacing with

ANSYS will be covered:– Named Selections and ANSYS Components– Using Commands Objects– Loading a Simulation Environment Directly in ANSYS

• The capabilities described in this section are generally applicable to ANSYS Professional licenses or above.


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A. Named Selections and ANSYS• As will be seen subsequently, there are different ways to

interface with ANSYS to access advanced functionality

• However, when the model is transferred to ANSYS, only node and element entities are sent– Solid model geometry is not referenced by the ANSYS solver– Because of this, it may be difficult to select or manipulate the

model if only the finite element mesh is present

• Named Selections provide a convenient way of selecting and manipulating the mesh– Named Selections are defined in Simulation– These are transferred as Components in ANSYS, where they

can be selected or manipulated, as needed.– To reference any “geometry” in ANSYS, the geometry must

first be defined as a Named Component in SimulationANSYS License AvailabilityDesignSpace EntraDesignSpaceProfessional xStructural xMechanical/Multiphysics x


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… Transferring to ANSYS• Named Selections transferred as ANSYS Components:

– Vertex, edge, and surface named selections are transferred as nodal components with the same name

– Named selections of solid, surface, and line bodies transfer as element components with the same name

• Change the selection filter to “Body”. This allows selection of surface and line bodies, not just solid bodies!

• The following conventions apply when Named Selections in Simulation are transferred as ANSYS Components:– Names beginning with a number have the prefix “C_” added – Spaces will be replaced by underscores– If multiple selection groups have the same name, only the last

one is converted as an ANSYS component

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… Transferring to ANSYS• Once Named Selections are transferred to ANSYS, they can

be referenced as Components to do the following:– Apply types of loads not supported in Simulation– Change element attributes– Define additional elements not supported in Simulation– Special postprocessing tasks– …etc.

• Most ANSYS commands accept component names as an argument, facilitating component use in ANSYS

• Named Selections are associative with the CAD geometry, so users do not have to worry if CAD model is updated

• Use of components is numbering-independent, so users do not have to worry if the mesh changes



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B. Overview of Command Objects• Command Objects enable users to add APDL (ANSYS

Parametric Design Language) commands, which expose advanced ANSYS functionality not otherwise available in Simulation– The Command objects requires that the user has familiarity

with APDL commands– Command objects can be inserted in the Part, Contact,

Environment or Solution branches:• Part branch: commands are inserted following the material

definition in ANSYS /prep7• Contact branch: commands are inserted following the contact

definitions in ANSYS /prep7• Environment branch: commands inserted prior to the SOLVE

command• Solution branch: commands inserted after the /POST1 command



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… Adding Command Objects• Adding command objects is done by right-clicking in the

appropriate branch and using “Insert > Commands”– A new branch with a Worksheet view will be shown where

APDL commands can be inserted.



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… Parameterizing Command Objects

• The details window for each command object can contain up to 9 parameter definitions (“ARG1 to ARG9”).– Just as with other detail information throughout Workbench

these arguments can be made parametric.

In this example a command object placed in the Environment branch contains the NSUB command. The syntax of the command is:NSUB, Initial substeps, max substeps, min substeps

Notice we have substituted ARG1 in the command resulting in:

Nsub, 10, arg1, 2

This parameter can be used throughout Workbench including DesignXplorer


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. . . Specifying Material Properties

• Command objects inserted in part branches allow quick material modification without having to know each part’s material number (ANSYS)

• In the example below the “mp” command is used to modify the Young’s modulus for the material used for “Part1”.– Notice the parameter “matid” is inserted into the command in

place of the material’s reference number.


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. . . Specifying Contact Properties

• Contact branch command objects can be used to modify ANSYS element type , real constant and material number data using parametric references.

• Can be used with symmetric or asymmetric contact pairs.

• Insert ANSYS commands using parametric references.


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… Obtaining Output Parameters• Inserting a Command Object under the Solution

branch allows for the use of postprocessing commands.

• Certain types of APDL parameters may be retrieved as Simulation parameters for use with design studies– A output “prefix” is specified (default is “my_”), so

all APDL parameters with that prefix will be searched and parsed.

– Output parameters can be used with Parameter Manager (discussed earlier in Chapter 10) or DesignXplorer, enabling inclusion of APDL commands



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… Retrieving ANSYS Output Information

• Command objects placed in the Solution branch can be used to retrieve plots from ANSYS

• Place the appropriate plot formating information (file type, size, etc.) in the command object.

• Issue the desired plot commands.

• ANSYS plots are placed below the command object.

• Plots are static images (see next page).


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… Retrieving ANSYS Output Information

• ANSYS plots are retrieved below the command object.


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… Linking with Text File• The Command Object’s contents can be exported or

imported to/from a text file:– The Command Object contents can be “refreshed” to reflect

current text file contents– In Details view, linked filename will be shown



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… Command Objects Summary• Command Objects provide a convenient means of adding

APDL commands to a Simulation model in order to access advanced ANSYS functionality not otherwise exposed– Commands branch provides pre- and post-processing access

inside of ANSYS, including linking contents with external text files (e.g., ANSYS input or macro files)

– When used for post-processing, certain parameters with a given prefix may be retrieved back into Simulation. This is useful not only to view APDL parameter output but also for design studies, such as with Parameter Manager or DesignXplorer

– For users not as familiar with APDL commands, the Preprocessing and Postprocessing Commands branches, discussed next, provide an alternate means of including ANSYS functionality within Simulation.



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C. Transferring Models to ANSYS• As seen in the previous section, the two types of

Commands branches allow the user to add ANSYS APDL commands within the Simulation environment to access advanced functionality

• In some cases, users may wish to transfer the Simulation model into ANSYS directly and run the model from there– All of these options will transfer the mesh only, not the solid

model geometry, to ANSYS

• There are three ways to transfer the mesh/loads to ANSYS:– Saving the Environment as a binary ANSYS database– Saving the Environment as an ASCII ANSYS input file– Loading the Environment in an ANSYS session


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… Saving the ANSYS Database• During solution, the ANSYS binary database can be saved

– In the Details view of the Solution branch, change “Save ANSYS db” to “Yes”

– Specify the ANSYS database filename in the “ANSYS db File Name” textbox, which will appear underneath

– Solve the model, which will initiate solution and save the ANSYS database (*.db)

– Things to keep in mind:• A solution must be initiated to create/save the

.db file• The ANSYS .db file will be saved in the active

units (Units menu)• This is also used in conjunction with saving

ANSYS result files after a solution (see next slide)

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… Saving Other ANSYS Binary Files• ANSYS files written during solution may also be saved:

– Use with the Postprocessing Commands Builder– Enable use to manually post-process within ANSYS later

• In the “Tools menu > Options… > Simulation: Solution,” user can save ANSYS files as well as specify where these files are stored. To save ANSYS files for each Simulation database, use the option “Use Project Directory.”

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… Writing an ANSYS Input File• An ANSYS input file may be generated,

independent of the Simulation solution– Select a Solution branch– Select “Tools > Write ANSYS Input File” and

enter the name and location of the input file– Things to keep in mind:

• As with saving the binary ANSYS database, only the currently selected Environment will be written. Write multiple input files for each Environment branch to be saved.

• Unlike saving the binary ANSYS database, this option does not require a Simulation solution. If loads/supports and requested results are incomplete, Simulation will not know what type of analysis to specify, so the model may be transferred as MESH200 generic ‘mesh-only’ elements. Otherwise, see previous chapters as to how the model will be translated to ANSYS

• There will be an /EOF command prior to SOLVE– To make the input file generate the mesh and solve, simply remove

the /EOF line in any text editorANSYS License AvailabilityDesignSpace Entra xDesignSpace xProfessional xStructural xMechanical/Multiphysics x


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… Loading Environment in ANSYS• It is possible to load an Environment directly into ANSYS:

– In the Workbench Project page, select a “Model”– On the right-side menu, one can list Environments contained

in that Model branch– Select the Environment of interest to load into ANSYS



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… Loading Environment in ANSYS– After selecting the Environment, the ANSYS Output Window

will appear, and the Workbench GUI will change to ANSYS– The analysis may be continued from within ANSYS

• Note that any actions performed in ANSYS will be captured in an ANSYS log file, but these will not be stored in Simulation

• When leaving ANSYS, the user will be prompted to save files



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… Loading Environment in ANSYS• All pertinent files from the ANSYS session will be stored in

a new subdirectory in the Solver Working Directory– The subdirectory name will be called “filename_num” where

“filename” is the name of the .dsdb file and “num” is the numerical Environment number

• For example, for the third environment branch of a Project.dsdb file, the subdirectory will be named “Project_3”

– All ANSYS-generated files, including the input file, error file, log file, and database, will be contained in the subdirectory

• filename_AWE.inp: text input file generated from Simulation and automatically read into ANSYS

• filename.db (optional): binary ANSYS database of mesh and loads• filename.err: text file containing all error or warning messages• filename.log: text file containing ANSYS command history• filename.page: temporary binary file (leave untouched)



Hyperelastic with Contact

Nonlinear Analysis of a Keyboard

Workshop 5


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D. Workshop 5 – Hyperelastic with Contact

This exercise will cover accessing ANSYS options through the Commands object. A 2D analysis of a portion of a hyperelastic keyboard will be performed, as shown below.– General use of Commands

object in the Geometry,Environment, and Solutionbranches

– Use of Named Selections willfacilitate manipulating datain ANSYS

– Output parameters and plotswill be retrieved from thesolution

– Items shown with roundbullet points are tasks to beperformed.


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…Workshop 5 – Hyperelastic with Contact

• Launch Workbench and open a new Simulation session

• Under the “Geometry” branch in the Details view:– Turn off import of solid and line

bodies and only select import of surface bodies

– Change the “Analysis Type” to “2-D”

• From the Context toolbar, choose “Geometry > From File…” and select the Parasolid file “keyboard.x_t”– The model will be attached to

Simulation, as shown next


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• Select the menu item “Units > Metric (mm, kg, N, °C, s, mV, mA)”

• Right-click on “Part 1” and select “Rename” to rename it to “ground”

• Likewise, right-click on “Part 2” and rename it to “keyboard”

• Right-click on “keyboard” and select “Insert > Commands” from the pop-up menu– In the contents of the Commands

object, type the following:mpdele,all,MATID

tb,hyper,MATID,1,,neo

tbdata,1,80.194



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The commands that were added in the previous slide delete the existing material properties for the “keyboard” part and replace it with a neo-Hookean hyperelastic model.– The “matid” parameter is used to

reference the material ID for that given part, so the element type or material can easily be changed using ANSYS commands

– The active Simulation units are used during analysis, so it is important that all materials defined in the Commands object have the same units as the active Simulation Units.

Contact regions can also be changed in a similar manner under the “Contact” branch.The ANSYS APDL parameters “CID” and “TID” refer to the contact and target real constant numbers.

mpdele,all,MATID

tb,hyper,MATID,1,,neo

tbdata,1,80.194



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• Using the Control Key, select both “ground” and “keyboard” from the Geometry branch– In the Details view, ensure that “Plane

Stress” is the “Behavior”– Enter “10” mm for the “Thickness”

In this example, the keyboard is assumed to have a plane stress state with a thickness of 10 mm.



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• Right-click on “Contact Region” under the Contact branch and select “Rename Based on Geometry”– The contact pair will be renamed to

“ground To keyboard,” as shown on the right

In this case, the automatic contact detection selected the top of the “ground” as the contact surface (red). We need to flip the contact pair such that the top of the “ground” is the target, as it is the stiffer material.

• Right click on “ground To keyboard” and select “Flip Contact/Target”



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• In the Details view, select “Contact”.– The bottom of the keyboard will be

highlighted. With the “Edge” selection active and the Control key pressed, select the other two lines as shown on the right, as these will be expected to touch the ground

– Click on “Apply” to complete the selection

– Change “Type” to “Frictionless”– Change “Behavior” to “Asymmetric”– Change “Formulation” to “Augmented

Lagrange”– Toggle “Pinball Region” to “Radius”

and enter “10” mm for the radius.



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• Select the Mesh branch and, in the Details view, toggle the “Global Control” to “Advanced”– The “Element Size” should be set to

“1” mm– Change “Curve/Proximity” to “100”– The “Shape Checking” can be

switched to “Aggressive”

• Change the selection filter to “Face” and select the “ground” part. From the Context toolbar, select “Mesh Control > Mapped Face Meshing”, as shown on the right– The “Element Shape” can be set to

“Quadrilaterals”



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• Change the selection filter back to “Edge” and select the four lines of the “ground” part, as shown on the right– From the Context toolbar, select

“Mesh Control > Sizing”– In the Details view, change “Type” to

“Number of Divisions”, with the number of divisions being 1

In this example, the ground is not of interest and is much stiffer than the keyboard, so it will be meshed with just one element.

• Right click on the Mesh branch and select “Preview Mesh”



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• Select the topmost line of the “keyboard” part and select the “Create Selection Group” icon– When asked for a name, enter

“PUSH_TOP”

A new Named Selection branch and PUSH_TOP object will be created in the Tree.

The Named Selection can be referenced as a nodal component in ANSYS Command objects in order to manipulate the model. In this case, a special loading will be applied to the nodes in “PUSH_TOP”



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• Highlight the Environment branch, then select the leftmost line of the “keyboard” part– From the Context toolbar, select

“Structural > Frictionless Support”

• Do the same for the rightmost line of the “keyboard” part and add a Frictionless Support there as well.



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• Select the bottommost line of the “ground” part– Add “Structural > Fixed Support” from

the Context toolbar

• Right-click on the Environment branch and select “Insert > Commands”– In the Commands object, select

“Import” from the Context toolbar– Select “keyboard2.mac” as the file– The contents of “keyboard2.mac” will

be inserted into the Commands object



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It may be worth pausing for a moment to examine the commands inserted from “keyboard2.mac”– All results are saved for each substep– The nodal component (Named

Selection) called “PUSH_NODE” is selected, and a coupled set for the y-direction is created for all of the nodes

– A displacement of –54 mm is applied in the y-direction on the master node of the coupled set.

– An element plot is generated, so the user can see the mesh and boundary conditions in Workbench Simulation

/show,png

time,54

outres,erase

outres,all,all

cmsel,s,PUSH_TOP

PUSH_NODE=ndnext(0)

cp,next,uy,all

d,PUSH_NODE,uy,-54

allsel,all

/pbc,all,1

eplot

/show,close



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• Select the Solution branch. In the Details view, change the following:– “Solver Type” to “Direct”

• This model has hyperelastic and steel materials, so the matrix may be ill-conditioned. The sparse direct solver will suffice for such a small problem.

– “Weak Springs” to “Off”– “Large Deflection” to “On”

• Although the text box may change to yellow, this is because no results have been requested yet.

– “Auto Time Stepping” to “On”– “Initial Substeps” and “Minimum

Substeps” of “10” and “Maximum Substeps” of “1000”



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• From the Context toolbar, select the following:– “Stress > Equivalent (von-Mises)”– “Strain > Equivalent (von-Mises)”– “Deformation > Total”– “Tools > Solution Information”– “Tools > Contact Tool”

• Change the Contact Tool detail to “Worksheet”, change “Contact Side” to “Contact” > “Apply”.

• Then RMB > Insert:– “Contact > Pressure”– “Contact > Penetration”



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There are some type of results that cannot be viewed directly from Simulation. These include load-history response (POST26) as well as element table items

• Right-click on the Solution branch and “Insert > Commands”– From the Context toolbar, select

“Import” and read in the “keyboard3.mac” file

– The contents will be displayed in the worksheet. Notice the inclusion of the output parameter “MY_REACTION” in the Details view.



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• The “keyboard3.mac” contains postprocessing ANSYS commands– The Time-History Post-

processor is used to plotforce vs. displacement at thetop of the keyboard

– The General Postprocessoris then used to get thereaction force due to pushingthe keyboard down. This isreported as “MY_REACTION,”which is also recognized bySimulation as an outputparameter that can be usedwith the Parameter Manageror DesignXplorer

– The resulting thicknesses are also plotted.

/show,png

/post26

rforce,2,PUSH_NODE,f,y,FORCE

/axlab,x,Displacement

/axlab,y,Force

plvar,2

finish

/post1

set,last

*get,MY_REACTION,node,PUSH_NODE,rf,fy

/title,Equivalent Stresses

plesol,s,eqv,2

/title,Out-of-plane Thicknesses

plesol,nmisc,1

/show,close



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• Click on the “Solve” icon to initiate the solution.

• Select the “Solution Information” branch to review the contents of the Output window.– The “Force Convergence” graph can

also be reviewed during solution to monitor the progress of the analysis

– At the end of the solution, a warning message may appear. The user does not have to worry about this, as the frictionless supports used in this example are fine for this large-deflection solution.



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• Select “Equivalent Elastic Strain” and review the strains.– Change the scaling in the Context

toolbar to “1.0 (True Scale)”– The undeformed model may also be

superimposed to get a better sense of how much the keyboard deformed.

– Note that the equivalent elastic strains are very large (~66%), as this is a hyperelastic model.

Review other results, such as stresses, deformation, and contact results. Contact pressure distribution is shown on the right.



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Note that under the Commands object in the Solution branch, there are four “Post Output” objects

– If no objects are shown under the Commands branch, click on the Workbench Project tab on the very top, then return back to Simulation tab to refresh the window

• Select “Post Output 2” – this is a plot of force vs. deflection in the y-direction.

– Note that the force is relatively small at first. Then, the slope changes when the front of the keyboard initiates contact. Another change in slope occurs when the middle contacts the ground.



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• “Post Output 4” shows the final thicknesses

– Recall that the initial thickness was 10 mm (Step 3)

– Because of the incompressibility of the hyperelastic material, some areas (yellow) became thinner while other areas (red) became thicker.

• “Post Output 3” shows equivalent stresses

– Note that the max stress in ANSYS is 141 MPa while max stress is 140 MPa in Simulation. This slight difference is due to the fact that ANSYS has different options for output, including averaged or unaveraged stresses, so the user has more control over output results with the Commands object.


Documents

[PPT]Interfacing with ANSYS - Lawrence Berkeley National …als/FEA/ANSYS_V9_INFO/Workbench... · Web viewChapter 5 Accessing ANSYS Options Chapter Overview In this chapter, the following