Negative CTE

[m.moschetti]

Dears,

I would perform a simple linear static analysis to understand displacements due to thermal loads. As usual, I make a  steady state thermal analysis, then on a duplicated model I select the temperature load from output.  The problem is that in the assembly, one material has a negative thermal expansion coefficient (1direction, ortothropic 3D properties). Nastran solution failed because of that. Is there any chance to do it?

Thank you in advance.

[John_Holtz · Accepted solution]

Hi @m.moschetti 

What is the message when the analysis fails? Please copy the full error or warning message from the log file. (Use Windows File Explorer to view the folder where the model is stored, then browse into the modelname > InCAD > FEA folder. Open the .log file with Notepad, find the error/warning, and copy the 3 or  4 lines associated with the warning.)

When you use a CTE of 0 or a positive value, does the analysis run?

John

[m.moschetti]

Dear John,

Thank you for the answer. I now understand the point from fatals. Here below the errors. It was not a matter of negative CTE, but the missing shear modulus of the ortothropic material. I supposed that were automatically calculated if Poissons are defined, as for isotropic. Sorry for the alarm. Please delete the post if it is spammy.

FATAL ERROR T2020: INVALID MATERIAL DATA IN FIELD 2
+X 0X -8.299-53.3999-51.0399-42.9300+2 0.0
^------^

FATAL ERROR T2020: INVALID MATERIAL DATA IN FIELD 3
+X 0X -8.299-53.3999-51.0399-42.9300+2 0.0
^------^

FATAL ERROR T2020: INVALID MATERIAL DATA IN FIELD 4
+X 0X -8.299-53.3999-51.0399-42.9300+2 0.0
^------^

WARNING T2265: USING INITIAL TEMPERATURE SET FROM MATERIAL REFERENCE TEMPERATURE