nonlinear static structural analysis. Apply increasing load in steps & release.

David_R

Using Optistruct & Hypermesh non linear static analysis, I wish to apply increasing load in steps and then release the load. I wish to see the residual deformation due to yielding of the structural steel once the applied load has been removed. 

This is not a transient time dependent scenario. I believe DLOAD, TLOAD1, TABLED1 cards may be relevant. 

1 - How are Optistruct users best able to learn this loading method? 

2 - where in the support documentation is this covered? This is a fundamental FEA topic.

Adriano_Koga

you can perform NL Static Simulation in OptiStruct, for this.

There are 2 ways:

• multiple NL Static loadcases with each loadcase final load value as desired (using CNTNLSUB option to create subsequent loadcases)
• single NL Static loadcase, using TLOAD1 and TABLED1 to create a pseudo-time table, with the carying load, as you've supplied in the table above.

For option #1, I would just run 1st loadcase from zero to point 5, and then 2nd loadcase from 5 to 7, and last subcase removing all load.

David_R

Thanks.

It was the CNTNLSUB option that I was not aware of & needed to add to my assumed method. This method then has the advantage that it allows different NLPARM, NLOUT, NLAPADT cards for each case.

Adriano_Koga

correct. For multiple loadcases, you're allowed to use different setup. You could also try the newer NLCTRL which replaces most of these into a single card.

Adriano_Koga

chair_nofllwer_twosubcases.fem

Time_dependent_Loading.pdf

chair_nofllwer_timedependent.fem

i've found these around here… 1 example using 2 loadcases, and another with a single subcase, "time" dependent.