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Assigning Initial Tension to Fasteners in Altair Inspire for FEA and Topology Optimzation

Louis_Shen

Dear all,

I have a question about applying initial tension to fasteners in Altair Inspire. In previous Altair releases (I believe I was on 2023), there was a section in the Property Editor for Fasteners to adjust its pretension, which is also explained in this post https://help.altair.com/inspire/en_us/topics/inspire/reference/FAQ_assign_initial_tension.htm .

After I updated my Aitair Inspire to 2025.1, the option to adjust the fastener pretension in the property editor no longer exists (see picture below).

Has the pretension feature been moved elsewhere?

Thank you very much for your help in advance!

Best regards,

Louis

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Accepted answers

SouravDas0306

Hi Louis,

Right click on the fastner and select new pretention group. The pretension functionality has not been removed in Inspire 2025.1, but its visibility is now more dependent on the active analysis setup and solver configuration. In previous versions, the pretension field was directly exposed in the Fastener Property Editor, whereas in 2025.1 it may only appear for supported study types. Could you please verify that the study is an OptiStruct static/linear analysis and that the model is not running in SimSolid mode? It is also worth fully expanding the Property Editor after selecting the fastener and checking whether pretension needs to be defined through a Pretension load/group in the Loads ribbon first. Since pretension is not supported for all analysis types, the option can be hidden depending on the current setup. If the option is still unavailable after these checks, please share a simple sample model and the study type so we can investigate further.

In a linear static load case you must assign pretension to a single pretension group, select the fasteners it applies to and enter the force. You can choose “Simultaneous” to load all fasteners at once and tick “Preload Result” if you want results showing only the pretension effects.

Known limitations:• OptiStruct frequency analyses with pretension are not supported.• SimSolid sequential loading with pretension is not supported.

Regards,

Sourav

All comments

SouravDas0306

Hi Louis,

Known limitations:• OptiStruct frequency analyses with pretension are not supported.• SimSolid sequential loading with pretension is not supported.

Regards,

Sourav

Louis_Shen

Hi Sourav,

Thank you very much for your response.

How do I check if my model uses OptiStruct or SimSolid? I know I can select between OptiStruct and SimSolid directly before running the analysis in the Analysis pop-up window. Is this what you mean? I simulated a simple model with pretensioned fasteners using OptiStruct and SimSolid, and both appear to account for the pretension.

Best regards,

Louis

SouravDas0306

Hi Louis,

Yes, that is exactly what I mean. In the analysis setup window, the solver you select before running (click on file > preference> Under Inspire run option and you can select the alaysis solver and choose) the simulation determines whether the model is solved using OptiStruct or SimSolid. If you selected OptiStruct, the analysis used the traditional finite element solver, whereas selecting SimSolid used the meshless SimSolid solver. Your test with a simple model containing pretensioned fasteners is consistent with expected behavior, since both OptiStruct and SimSolid support bolt pretension effects and can account for preload in the structural response, even though they handle the underlying calculations differently.

Regards,

Sourav