Definin Plastic material in ABAQUS

[AdekunleAdeniyi]

Hi,

I am tryin to define a material porperties for a polycarbonate sheet in Abaqus 6.8 but I am finding it difficult.
I have defined:
Density
Poisson ratio
Young's modulus

I am trying to add the plastic property. I am tryin to enter the plastic strain values but due to the material softening, some stress values have two strain values.

Any idea on how to define the plastic property will be very helpful

P.s. I have attached the stress-strain graph.

 

[Nileo2005]

Just input two points of stress/strain data and Abaqus should interpolate between them in search for your value. Hit enter after you put in your first two points and the curser should form a second row. I think this is what you're asking for, but not positive. Hope it helps!

 

[bassmanjax]

You'll struggle to get that exact curve with *PLASTIC, as ABAQUS requires a monotonically increasing function to describe the plasticity curve.

http://en.wikipedia.org/wiki/Monotonic_function

You'll need to simplify the material model to be able to use *PLASTIC, or look at a different type of model, such as viscoelasticity.

Just bear in mind that *PLASTIC is intended for metal plasticity, not for modelling polymers.

Regards

Martin Stokes CEng MIMechE

 

[vumat721]

I'm not sure I would trust that your experimental data. The data looks like it is from a displacement controlled loading situation, in which case it would be impossible for you to have more than one stress point for each strain point. I would suggest approximating your curve by ignoring the points after your bulge that seem to go back in strain.

Also, *Plastic is fine for modeling polymers. So long as you are not concerned about unloading behavior.