how to get the material non linearity results in optistruct.

Question

In my current simulation, I need to establish contact between two components. Initially, the contact occurs at a single point(small area), but as the load increases, it transitions into surface contact. However, during the simulation, the initial point contact leads to excessive localized plastic strain at a single node, causing convergence issues.

Could anyone suggest the best approach to obtain accurate material curve results while avoiding or minimizing these unrealistic plastic strains in the assembly?

Rajashri_Saha · Answer

If you want to remove those elements then use MOADCHG option to deactivate those elements from the analysis.

Refer below link for this.

https://help.altair.com/hwsolvers/os/topics/solvers/os/modchg_sub_r.htm?zoom_highlight=modchg

Thanks

Rajashri

Surya Koneti · Answer

Hi Rajashri,

Thank you for your attention to my query.

In my case, the geometry involves a sharp edge with a relatively fine mesh. The contact defined in the assembly is a standard contact, where the sharp edge tends to protrude into the opposing surface. In addition to the primary and secondary components, the assembly also includes softer components that are expected to undergo plastic deformation.

At this stage, I would like to exclude the localized plastic deformation occurring near the sharp region and focus on obtaining the material curve results for the remaining components. Could you please suggest a suitable approach or best practice to achieve this effectively?

Apologies, but I am unable to share the .fem file.

Regards,

Surya

Rajashri_Saha · Answer

Hi,

The plastic strain might be due to excessive deformation.

If it is a sharp feature, try to remesh with smaller mesh size and define main and secondary surface correctly. You can use CONSLI in contact card if it large displacement analysis with additional SMOOTH option. In case the parts are of different material, try STIFF=SOFT in PCONT card.

Thanks

Rajashri