creep in femap

[domenicob]

hi there, i'm new to fem and femap environment
i would like to know how to perform a creep analisys with femap using MSC nastran.
I got some trouble in the analisys selection.
I read somewhere on the user guide that i have to run two different subcases the first with a static load and the second with the same loads but with the creep analisis set in Model>loads>NonlinearAnalisys.
what kind of analisys do i have to select when exporting the files? (static,nonlinear transient...etc)

 

[brkica]

Creep is time-dependent so you may set it up as a transient analysis with an elasto-visco-plastic material. I have never done creep in Nastran, but you certainly need one of creep models of the form creepstrainrate = f(stress,creep strain, time,temperature) with f = function depending on stress or stress and time. However, you can also include temperature effects but also make it dependent on evolved creep strain.

These are socalled power law based creep models. Usually it means that you need exprimental data in order to fit one of the models to experiments in order to determine model constants, as the program only asks the model constants which are usually unknown unless you do experiments en fit the curves.

Regards.