results nastran and inventor

[Anonymous]

Why am i getting different results in Inventor simulation and nastran in cad simulation???

[Roelof.Feijen]

Hello @Anonymous ,

There can be a lot of reasons why you get different results.

Inventor Simulation uses a different mesher.

• make sure that in both applications the mesh matches reasonably
• that you use the same element types

Make sure the set-up, loads and constraints are reasonably comparable.

We can only say something about the cause for your analysis if we can compare the two analyses. I suggest you add your model here.

[Anonymous]

Please see the attached model

[Roelof.Feijen]

Hello @Anonymous ,

I am unable to solve the Inventor Stress Analysis study. So I can’t compare the results. What I can see is that there is a different setup in the loads/forces. There is one load in Inventor Stress Analysis added to another face than in Inventor Nastran. In Inventor Nastran there is also a load added to a face that is fully constraint. I would suggest to review the setup in both FEA software, before you start comparing the results. 

[Anonymous]

Hi, please see the corrected one. In this you can see the different results.

[Roelof.Feijen]

I am not sure why, but I can't solve your model in Inventor Stress Analysis. I tested it on two different workstations.

Maybe someone else can compare the results?

[John_Holtz]

Hi,

I cannot run the Inventor Stress Analysis either because the model will not mesh. I do not know why the model does not mesh.

If I export the model to STEP and open it, it will mesh. But it has lost all of the splits.

@Anonymous. 

• The displacements should be close to being the same. If the displacements are different, it is because the input is different (loads, constraints, material properties), or the mesh is not fine enough to converge to a solution.
• If the maximum stress value is different and occurs at the edge of a constraint, it is because analysis does not do a good job with edges of constraints. If you refine the mesh, the stress will increase each time: this is an inaccurate stress. When you have a real stress concentration, the result will stabilize once the mesh is fine enough. Therefore, you should ignore the maximum value that occurs and compare results that are not adjacent to the maximum value. The results should then compare between Inventor Stress Analysis and Inventor Nastran.

If one of the above items is not the answer, please tell us which result is different, and include images of it.