The Unit Temperature Increase validity check

[test123123]

Is the connection function in FEMAP not valid for thermal analysis?

I wanted to verify the validity of the FEM model by setting RBE2 and all materials to the same CTE and increasing the temperature by only 1 degree to check if the stress remains zero.
However, stress is still being showed in the local place using FEMAP-Connection-glue.

One side of the box is fully constrained with all 123456 degrees of freedom.

 

[karachun]

It is hard to understand your setup only from text description. Can you post some pictures or maybe share input .dat file for some simple test model.
If you have one side fully constrained than you definitely have some stress in your model.

UPD. Maybe try 3-2-1 constraint method instead of fully fixed side to allow structure to expand freely.

Free-Floating FEA Models - Digital Engineering

Apply equivalent pressure distributions on a structure without needing direct constraint boundary modeling with the 3-2-1 method..

www.digitalengineering247.com

 

[SWComposites]

RBE2 elements do not have any properties including CTE, nor do they deform under any type of loads.

And yeah, post a picture.

 

[karachun]

RBE2 elements have thermal expansion coefficient for thermal stress problems.

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Also this remark may be interest.

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By default CASE CONTROL command RIGID=LINEAR so maybe this is cause of problem.

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[SWComposites]

well that makes no sense at all. a rigid element that expands??

 

[karachun]

This make sense to add RBE2 element ability to expand so it do not produce artificial stress when used for example in bolt modeling or if RBE2 element used for beam to plate transition.

Thermal expansion is just change of linear dimensions, in don`t require cross section or thickness only thermal expansion coefficient.

 

[BlasMolero]

Hello!,
For THERMAL GLUE coupling tutorial with Simcenter FEMAP & NASTRAN please visit my blog in the following address, all is explained in detail step-by-step:

51.- Thermal Coupling Tutorial

Hello!, This is my first tutorial fully written on english, then I beg your pardon for any sintax error or mistake I made have — thanks!. In the following link you have a FEMAP & NX NASTR…

iberisa.wordpress.com

The old link here:

Heat Transfer from a Chip to PCB (Printed Circuit Board)

Best regards,
Blas.