How to create a submodel?

[PierreMalouf8976]

Is it possible to create a sub-model of a specific component from a half-model, along with its corresponding temperatures, and then perform a non-linear stress analysis on the component?

For background information, I am conducting a non-linear thermal analysis with the aim of assessing the stress / deformation of a particular component within the assembly.

So far I have created a half-model of the mechanism to be evaluated and obtained realistic temperature results.

Analyzing the non-linear stress of the entire half-model  based on the temperature distribution takes a long time. It is also very laborious.

Having the ability to create a sub-model would speed up the process, which is the reason for my initial inquiry.

The only other option would be to create a separate FEA model of the component and manually enter the temperatures based on the half-model. This is something I am trying to avoid.

Best regards,

Pierre Malouf

Consulting mechanical engineer-railway rolling stock

[roman.gebhard5MV47]

As far as i know, Inventor Nastran has not the capability to create a submodel.

I created a manual way myself for submodelling in Inventor Nastran, but this wont be efficient at all.

The model i created was just for testing. if you are still interested, let me know!

[PierreMalouf8976 · Accepted solution]

I agree with you that Nastran lacks the ability to create a submodel. It would be good if this feature was added to Nastran.

I was able to find a workaround for the analysis I am doing. It involves solving a half-model of the system and then transferring the results to a smaller model. More specifically,

1. A nonlinear transient heat analysis is done on the half model.

2. The temperatures for the submodel are taken from step 1 (basically written down on a piece of paper).

3. The submodel is partitioned in smaller sections to which a temperature is assigned and a linear thermal analysis is done. The assigned temperature is based on the results of step 1.

4. The linear thermal analysis of step 3 assigns temperature values to the individual nodes of the submodel.

5. The analysis of step 4 is duplicated and used to run a nonlinear static analysis. Boundary conditions are assigned to represent conditions from the half model and the temperatures of step 4 are used as an input.

6. This allows me to obtain the stress distribution when the submodel is heated.

As you can see, it is labor-intensive.

I would be curious to know how you proceeded.

Best regards,

Pierre Malouf

[John_Holtz]

Hi Pierre,

I agree with your steps. 

When Nastran uses the temperatures from a heat transfer analysis as a load in a stress analysis, the temperature are transferred from node 1 in the thermal model to node 1 in the stress model, node 2 to node 2, through node N (in whichever model has fewer nodes). Therefore, the thermal model and the stress model need to have the same mesh.

John