Plastic finite element analysis

[Jai460]

I am using NX-NASTRAN for the plastic component non linear analysis.I gave youngs modulus,poison ratio,shear modulus,stress-strain curve at particular temperature as the mechanical material properties.I have selected type of non linearity as plastics ,yield function criterion as von mises and Hardening rule as isotropic.In addition to that,I gave yield strength value,ultimate strength value,Thermal expansion coefficient value,thermal conductivity value,specific heat value in the material properties.
I have solved the problem with appropriate boundary condition.I have selected solution type as NLSTATIC 106-single constraint because it is basically a static analysis.
while solving i am getting error like"FATAL MESSAGE 316 (IFPDRV):ILLEGAL DATA ON BULK DATA ENTRY MATS1"
i got the error after including stress-strain curve in the material property.
My question are.
1.Whether my assumptions are right for plastic analysis?
2.whether i need to include some other properties also?
3.How can i overcome fatal message 316 in NX NASTRAN?

Thanks in advance

 

[rb1957]

3) are you entering the data onto the MATS1 card directly, or are you using a pre-processor (so you type in your parameters, and it writes the card) ?

can you export the nastran bdf (or echo th einput in your output) and see what's written on the MATS1 card ?

you could have written two numbers (ie have two decimal points) in one data field; unless you're using free format input.

Quando Omni Flunkus Moritati

 

[rothers]

What does your stress/strain curve look like ? Make sure your using true stress/strain values (no negative gradients) otherwise the material model may compute a negative stain hardening modulus - not good.

 

[inline6]

NX Nastran SOL106 and even MSC Nastran 106 are terrible for highly non linear problems with plasticity it has so many problems converging

 

[rothers]

That's been my experience as well, really need SOL601 for anything more than small displacements.