Linear or nonlinear

[ptc-5735041]

Dear gentlemen,

I have here a stress analysis. I have done it with both linear and nonlinear methods using creo simulate 2.0.

In linear case, the stress result is almost 50% more.

Now these are the questions:

1) why is the model in linear case stiffer than nonlinear?

2) which one is more trustable?

Thank you very much

Mahdi

[dtran]

hyper elastic is used for flest and bone or rubber like material. don't use it for metal

here is the difference between linear and non linear in the case of metal:

For linear study (Hook's law) ,  stress = Young Mod * strain.

For nonlinear.

1 Truth stress strain curve

2 elastoplastic with perfect plastic deformation

3 elastoplastic with strength hardening.

Most of engineering application (95%) falls into the linear elastic.

If the secondary stress (caused by  contact or geometry change) is too high, None linear can be employed. Don't look at the stress level. examine the equivalent plastic strain (guild line per API-8C). it was good to study the affect of the local singularity of the geometry.

Answer to your Q1. Stress in None linear study does not follow the Hook's law, and thus it is smaller than the other

Answer to your Q2. Both are good.