Nonlinear constraints (Boundary) of shell colume structure

HYLI

Hello everyone,

I am currently using OptiStruct to simulate pile-soil interaction and have encountered some challenges that I hope to get your insights on.

In my model, the steel pipe piles are simulated using shell elements. To accurately capture the pile-soil interaction, I need to apply nonlinear boundary conditions at different positions along the piles. Specifically, some degrees of freedom in these boundary conditions should not be completely rigid but instead exhibit nonlinear stiffness. However, I am unsure how to implement this in OptiStruct.

Could anyone provide guidance on how to define and apply such nonlinear boundary conditions in OptiStruct? Any suggestions or references would be greatly appreciated!

Thank you in advance for your help.

Adriano_Koga

i believe the way to go is using the PBUSH/PBUSH1D spring elements in order do add some stiffness/flexibility into your model.

You can create what is called a 0D element. This is basically a grounded spring, and one end is fixed(SPCed) and the other is connected to your structure, just like you have sketched.

You can define some custom spring stiffness to your model.

https://2022.help.altair.com/2022/hwdesktop/hwx/topics/pre_processing/geometry/springs_create_t.htm

solon

Hello,

You can have a look at the bellow discussion as well, on how to create non linear spring for Optistruct

https://community.altair.com/discussion/39758/how-to-model-non-linear-spring-in-optistruct