Defining plasticity

[john84]

Hi,

I have a stress vs strain curve of a material and want to define a elastic plastic model. From the curve, I filled in the values of yield stress and plastic strain. Since the analysis is nonlinear, I will have to define the load with respect to time i.e. time dependent load (history loading). For that steps have to be defined. How do I define steps in order to make abaqus understand about the elastic as well as plastic region?I am not very clear on how to define the time period, the increments even after going through the manual.

Is it like the first step which would be defined should be linear region, the second should be yield point the third plastic deformation and so on?

Can anyone explain me in detail?

Thanks in advance.

 

[portliner]

You must make partitions of your geometry reflecting the elastic and plastic regions. Define an elastic material and a plastic one and assinh them to their proper partitions. You can not trigger the elastic or plastic material behaviour through the STEPs.

/Stig

 

[MechIrl]

You do not need to implicitly specify transitions for elastic/plastic behaviour. If the stress in the material exceeds YS then there will be plasticity regardless of choice in step time. However,due to material non-linearity it may be neccesary to ensure you use a few incrmeents within a step to ensure solution convergence.