abormal von mises stresses and peeq values

[neslon]

Hi all!

I have an elastoplastic material defined by a Mises yield surface defined by the following input

*Material, name=Mat1
*Damping, alpha=2000.
*Density
7.8e-06,
*Elastic
196000., 0.3
*Plastic
375., 0.
400., 0.009
500., 0.0464
600., 0.1145
676.09, 0.1965
700., 0.2474
710.87, 0.3233

I am performing an explicit analysis and several parts of my structure (at least 5% of the "elements") have von mises stresses and peeq values bigger than the last point of the plastic data (710.87, 0.3233). Is abaqus interpolating beyond (710.87, 0.3233)?

Thanks in advance.

 

[StefCon]

Hi,
I think it extrapolates yes. 32% plastic strain is a lot. Extrapolation beyond this value might not be physically correct. Remember to activate nlgeom for large deformations (and plastic materials).

Regards,

 

[neslon]

Hi.

I am using data presented in this paper "The Stress–Strain Behavior of Coronary Stent Struts is Size Dependent Ann Biomed Eng. 2003 Jun;31(6):686-91." for 316L stainless steel.

Here you can find the stress-strain plot that I used (150micron curve). (

http://imageshack.us/photo/my-images/191/30l1.png/)

So it makes sense having 32% plastic strains... Right?