AUTODESK INVENTOR FEA ANALYSIS TUTORIAL

AUTODESK INVENTOR FEA ANALYSIS TUTORIAL

By: Jonathan DeRoner

This tutorial is to serve the purpose of performing calculations within the stress analysis environment of Autodesk Inventor Professional. While the environment may slightly change in terms of layout during each release, this will give the basics on how to set up the different types of calculations that can be performed. This tutorial is being written using Autodesk Inventor Professional 2014.

Getting Started

You will first want to begin by opening the desired part in Inventor. For this part of the tutorial we will be using a simple 1 X 2 inch rectangular beam that is 12 inches long. Name: FEA Tutorial Bar

A- Defining Material

Inventor has a very large library of materials to choose from for your parts that you produce. By applying these materials, this will make calculations that we will be doing as accurate as possible. For this part we will be applying Mild Steel as our material to the rectangular beam.

Step 1: Click on the dropdown list above and locate Steel, Mild in the list. You will notice that once you select the material that the color of the part changes to a brighter gray color. This means the part is now made of mild steel in Inventor.

Tip: If you cant find the material you are looking to apply to a part in the basic drop down list of materials, the Autodesk Material Library at the bottom of the dropdown list will update the current list and will give you a much wider array of materials to choose from. You can also check the physical properties of the material by clicking the material icon next to the dropdown list.

This will bring open the Material Browser menu where you can check the physical properties of every material. You can even edit existing materials and create your own new ones relative to what will be used in the part you are producing.

B- Getting Setup in Stress Analysis Environment

Now that we have our material defined, we can begin FEA analysis in the Stress Analysis environment.Step 2: Click on the Environments tab and then the Stress Analysis Icon.

This will take you to the Stress Analysis environment where we can begin setting up our simulation. We first need to create a simulation however.

Step 3: Click on the Create Simulation icon. A menu to set up the simulation will then appear. Simply click OK to accept the default setup. You will then notice a new array of tools to use .

As of now, this is what your screen should look like.

C- Applying Constraints

Applying constraints properly is very critical in the Stress Analysis environment. Improper application could result in improper and incorrect calculations as the end result. You ALWAYS want to double-check and make sure you have everything constrained the way a part would be as close in relation to the real life scenario the part will be used for as possible.

For this simulation we will be simulating the 12 inch long Mild Steel Beam as if it were welded to the side of an existing structure. Even though we have no other structure in place, our constraints will help us simulate the situation. There are 3 types of constraints to choose from, however, for this tutorial, we will only be using Fixed constraints.Step 4: In the Constraints tab, click on the Fixed constraint icon.

You will then be prompted with a menu to select a location for the constraint. For this simulation, select the back, 1 X 2 inch face of the beam. You will have to rotate the beam to select the face.

Once you have selected the face, click OK. This will then close the menu. You will notice in the simulation browser on the left that in the constraints dropdown, there is now a fixed constraint in the browser on the face we selected.

Make sure to rotate the view of the part to the original view we began with after the constraint has been placed.

E- Applying Proper Physical Forces

When applying forces, its best to research the type of force that will be acting upon the part before applying the force to proper area of the part. You will notice in the menu there are 5 different forces to choose from in the Loads menu.

You have Force, Pressure, Bearing, Moment, and Gravity. Typically every situation will have gravity as a factor so we can define gravity easily by selecting the gravity icon.

Step5: Click on the Gravity icon and the following menu will appear.

The amount shown is Earths default gravity. We then need to select the direction gravity will be acting on the part.

Step 6: Select one of the vertical edges of the part.

Notice an arrow will appear relative to the direction of the edge shown. If the arrow is not pointing in the direction desired, this can be flipped or adjusted with the gravity menu as shown by simply flipping the direction, or adjusting the XYZ coordinates of direction in the gravity dropdown.

Once gravity is set properly, click OK the arrow for the direction of gravity will remain shown on the part. Gravity now will also appear under the Loads dropdown in the simulation browser.

Now we can add our force that will directly be acting on the part. For this simulation, we will have a 25 lbs of force (NOTE: Not Pressure/PSI) on the top face of our rectangular block.

Step 7: Click on the Force icon in the loads tab.

The following menu will appear asking us to select a location.

Step 8: Select the top face of the rectangular block. Then in the magnitude tab, type in 25. The force tab will recognize that it is 25 lbforce.

Click OK when finished.

Your screen should look like the image below when finished this step.

In any simulation we may create, there are 3 very critical steps to complete before we run any simulation. We need to define our material the parts will be made out of, define the constraints of the part, and the loads that will be acting on the part. We have now completed all 3 basics and are now ready to run our simulation.

F- Running the Simulation

Up to this point, we have completed all the basics to running a simulation in the Stress Analysis Environment. We have defined the material of our part, defined the constraints, and the loads that will be acting on the part. Now we can run the simulation.Step 9: Click on the Simulate icon.

The following menu will then appear. When it does, click Run and then Inventor will generate the simulation. This may take a few minutes to complete.

Your screen will look something like the image below when the simulation is complete.

This means the simulation is finished and we can see the results of our simulation. The 3 types of results you will want to check are the Von Mises Stress, Displacement, and Safety Factor.

The Von Mises Stress is the amount of stress occurring on the part at a time during the simulation and is the default result always shown. Your results should be similar to those shown below.

We can then check the displacement and safety factor as well.

Step 10: Double-click on the Displacement result in the simulation browser and this will then show the displacement results.

While the results seem exaggerated compared to what they really are, there is only a displacement of .001 inches which is very little. We can change the level of exaggeration of the resulting image under the display tab.

Step 11: Click on the display dropdown and select Actual. The image will then change and the actual level of displacement can be seen on the part. You will notice that there is very little change in the image now.

Never be quick to judge what you see in the results right off the bat. Inventors default representation is to multiply the effects in the image shown so you can see what the results of the forces are doing to the part in the simulation.The next thing we will want to check is the Safety Factor.

Step 12: Double-click on the Safety Factor result in the simulation browser and the screen should look like the image below.

The safety factor isnt listed because it is well above the range listed. So to see a safety factor, we are going to adjust the amount of force acting on the beam.

Step 13: Double-Click on Force 1 in the simulation browser and change the force to 500 lbforce and click OK

We need to update the simulation so we will run the simulation with the new force acting on the beam.

Step 14: Click the Simulate icon and then click run.

The simulation is now updated and there are new results listed under the Von Mises Stress, Displacement, and Safety Factor.

Step 15: Double-Click on Safety Factor results in the simulation browser. Your screen should show similar results to those shown below.

Now that we can see the Safety Factor, this beam maintains a Safety Factor of approximately 3.55 with 500 lbforce pressing down on the top face. As long as a part has a Safety Factor above 1, it is ok to use. The higher the results are above 1, the better. If the results are ever below 1, the design would likely fail and be a safety hazard if used in the real world for the intended purpose. This is the end of part 1 of the tutorial. G- Making Calculations Precise

In many cases, we usually only want a force to apply to a specific part on the face of an object. If we know where that force will be precisely and how much there will be, we can edit the part itself to reflect where the force will be acting. In this simulation, we will be seeing the results of force acting on the end of the beam in a 2 X 2 inch region at the very end of the rectangular block. Step 1: Open the FEA Tutorial Bar and create a sketch on the top face. (Note: If you have the FEA Tutorial Bar still open from the steps before, close the file. Do NOT save any changes to the part and re-open the original)

Make sure to create a 2 X 2 inch rectangle at the end of the top face as shown. Once this is complete, click Finish Sketch

We will then want to split the face of the rectangle.Step 2: Click on the Split tool in the modify tab and follow the instructions below.

Step 3: Inventor prompts us to select a split tool. So in this step, select the rectangle we sketched previously.

You will then need to select the face of the object to be split. Click on the Faces tool and select to the top face. Then click OK

The top face of the rectangle has now been split into 2 separate faces on the screen as you can see in the image below.

To make the faces easer to distinguish in the FEA environment, we are going to change the color of the new split face to beige.

Step 4: Click on the new split face and then click the Color Wheel icon in the top left of the screen.

The following menu of colors from Inventors library will appear. Click on the color Beige and upload it to the parts face by clicking the icon and then the Add appearance to document command that will appear just below the icon. You can always select other colors also. Once finished, close the browser.

Your part should look like the image below.

Now we are ready to run the simulation again. Follow the directions as listed previously for applying material of mild steel to our part before moving on to the Stress Analysis environment.Step 5: Under the Environments tab click on the Stress Analysis icon and then create a new simulation. Accept all the defaults given.

Your screen should look similar to the image below when finished.

We are now ready to apply the constraints and loads just like we did before. Only this time, the load will be placed on the face that is colored beige instead.Step 6: Apply a fixed constraint to the back face of the rectangle.

The constraint will appear in the Simulation browser like we have seen before.

Now we are ready to apply the force to the split face of the rectangle.

Step 7: Click on the Force icon and then select the beige face of the rectangle. Notice that the force is now only being designated to the face we have created.

Change the force amount to 500 lbforce and then click OK

Note: Make sure to define gravity after applying the 500 lbforce by selecting the edge like we did previously.

Your screen should look like this when all these steps have been completed.

Now we are ready to run the simulation again since we have the 3 essentials for any simulation. We have defined our material, our constraints, and our loads.Step 8: Click the Simulate icon and then run the simulation.

You will now notice a great difference in the results as they now relate to the force only acting on the 2 X 2 inch face rather than the whole top face of the rectangular block. Your results should be very similar to the ones listed below.Von Mises Stress

Displacement

Safety Factor

Even with the 500 lbforce now being more concentrated at the end of the rectangular block in relation to where it is fixed in the simulation, it is still able to hold a safety factor above 1.

H- ConclusionMaking sure that a simulation is run as close in relation to what a part will be doing in real life is very important and having knowledge of how these simulations work is key to getting the correct results that would also be relative to those we would otherwise perform hand calculations to obtain. Always make sure when running simulations that you have the 3 factors that need to be defined before jumping to conclusions of the results that are given. 1. Always define a parts material. 2. Always make sure the constraints are defined correctly in relation to where a part will be and what it will be doing. 3. Always make sure the forces acting on a part are input correctly and as precise as possible. Even to obtain maximum precision, some small edits need to be made to a part to relate to what a part is supposed to do in many cases. These simulations will help save time when determining the capabilities of parts and also help determine if a part is safe for use before it is even produced.