Learning Forum

[Morgan Ramanauskas]

Hi All,

I'm having issues getting COMBIN39 springs to work in compression only. I have activated the beta features and have the springs set to compression only, however, using spring probes I can see that the springs which are loaded in tension still have loading applied. I need to include all of the springs as in future the load will change direction based on the load step. 

Is it possible to use COMBIN39 in compression only?

As an alterative can springs be activated/deactivated for differnet load steps?

Any help would be greatly appreciated.

Kind regards,

Morgan

[dlooman]

At 2023R2 Mechanical error traps an attempt to make a nonlinear spring Compression Only.  Combin39 doesn't have a Compression Only option (interestingly, it does have a tension only option!).  When you make a spring "Compression Only" Mechanical uses a link180 element which doesn't support the nonlinear stiffness.  So it's sort of a catch22.  With APDL commands you can define the COMBIN39 force displacement in compression and tension.  A workaround within Mechanical would be to connect the nonlinear spring to an extra body and then define nonlinear (compression only) contact between that body and the surface you had intended to connect the compression only spring to.