Altair RISE

A program to recognize and reward our most engaged community members

Nominate Yourself Now!

rubber thermal analysis

My current requirement is to analyze the thermal deformation and stress of an entire rubber material structure when its temperature decreases from the initial 100℃ to 50℃. However, I found that the resulting contour plot from the analysis shows zero values, which suggests that the coefficient of thermal expansion is not functioning, or perhaps I have entered the expansion coefficient in the wrong location. I checked the help documentation, but I'm still unsure: for the hyperelastic material (MATHE card), is the thermal expansion coefficient indeed input at the TEXP parameter, or should it be set in another location?

Thanks！

Find more posts tagged with

OptiStruct

v2022

Accepted answers

solon

You are not running with large displacement but with small displacement theory. To activate it you have to add param,lgdisp,1 in your bulk data or NLPARM(LGDISP) in your subcase definition.

All comments

solon

Hello,

You have to run a nonlinear large-displacement analysis to account for the effects of the thermal expansion coefficient using MATHE.

h_h

Thank you very much for your answer.

Yes, I did use a nonlinear large displacement analysis step, but the resulting contour plot still shows zero results after the analysis. For comparison purposes, I created a hyperelastic material and a steel material in the model, selecting material cards MATHE and MAT1 respectively. I know that the thermal expansion coefficient is entered at position A in MAT1, and after consulting the help documentation, I confirmed that the thermal expansion coefficient for the MATHE card is entered at the TEXP parameter. In the final analysis, it turns out that this analysis method has an effect on the steel material, but not on the rubber material.

May I ask what the reason is?

solon

Can you share the model or a representative example, with us?

h_h

rubber_thermal.hm

Thank you for your reply. Here is my model – could you please help check for any errors? Thank you very much!

h_h

Thank you very much. What you mean is that when I perform rubber thermal analysis, I need to create an NLPARM card and input it at the NLPARM (LGDISP) section in the analysis step, right?

h_h

I’ve got it clearly. I greatly appreciate your solution; it’s been incredibly valuable.

h_h

Excuse me. Earlier, you mentioned that the NLPARM (LGDISP) card should be activated when temperature effects need to be considered for rubber.
For comparison purposes, I have adopted the same load boundary conditions and am temporarily not taking temperature into account.
Due to relevant analysis requirements, I used RBE2 to couple the inner surface, applied a forced displacement at the coupled point, and finally extracted the reaction force of the coupled point using SPCF. It was found that there is a significant discrepancy in the extracted reaction forces between the cases where NLPARM (LGDISP) is activated and where only NLPARM is used. Based on engineering experience, the reaction force extracted from the analysis with the NLPARM card activated is more in line with practical conditions. How can I resolve this issue?