General Mechanical

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Different results when I am using substep

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Subscriber

I got different results using one substep and dividing two substeps in static structural. I have a geometry including two parts with different materials. for the 120s, we have only decreasing the temperature and then they separate in the next 120s, so we have a peak in Von-mises stress. When I simulated that in one substep and controlled the changing using tabular everything is ok. But, when I divided it into two substeps, the answers will be different and are not reasonable. What is the problem? I have to divide my simulation into two substeps in this step due to applying a function for one of boundary that does not work in the first 120s, which I have to deactivate. Please guide me. Also, my other question is that if use just one substep, I can define an if clause through command (because the deactivate option will be applied for the whole simulation, so it is not an option for one substep). How can I do that?

• Aniket
Ansys Employee

Can you explain your problem in some more details? which analysis are you doing what are boundary conditions?

-Aniket

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Subscriber

Excuse me, I cannot post my geometry due to some reasons. I have elastic material on a viscoelastic material. The viscoelastic one was fixed at the bottom and has an interface (frictional contact) with elastic material at the top edge. We have the simulation for 240s at all. In the first 120, all the other boundaries like the left and right sides of both materials are confined using defining a zero displacement in all directions (the top edge of the elastic materials is free). During this period, the temperatures of both materials decrease from 200 C to 100C (experienced a shrinkage), then in the next 120 s, all boundaries remain the same except there is no change in the temperature and a displacement is applied to the top edge of the elastic material, and they will be separate, so we have some Von-Mises stress in both materials. When I have just a number for displacement on the top edge of the elastic, I can have the whole simulation in one substep and the results make sense. However, when I want to define an equation for that, I have to define a function, and it will be defined for the whole process, however, I do not have displacement in the first 120s, so I need to define that with an if clause through a comment to be applied the equation after 120s ( I have no clue for this option). Or another option, defining the problem in two substeps with active and deactivate options for different amounts at each substep. However, my results with two substeps do not make sense because I tried the simulation with two substeps even with just a number on the top edge, but it cannot repeat the same results with one substep for the previous model without an equation. I guess there is a bug in static structural when we defined substeps. Please let me know adding an if clause comment for one substep or my problme for two substeps.

• Rahul Kumbhar
Ansys Employee

This may be material definition or setup issue. Please see if you can create sharable model and share it here. Volunteers may help you once verify the model setup.