How to define bilinear elastic-plastic material in Abaqus?

[SteveFinnan]

I'm having problem to define the bilinear elastic-plastic material. I have the following information.

density = 7800 kg/m^3
Young Modulus = 193 GPa
Yield strength = 207 MPa
Poisson's ratio = 0.27
Tangent Modulus = 692 MPa
Shear Modulus = 75 MPa

I already ran the first simulation, but the result varied too much. This is because I didn't include Yield strength, Tangent Modulus and Shear Modulus.

After that I defined again the property, this time I include the Yield Strength and the plastic strain. And the is the same as the first simulation.

Yield Plastic
Strength Strain
207 0
300 0.05
370 0.1
390 0.15
380 0.2
350 0.25


So, I think Tangent Modulus is important in determine the outcome. However, I do not know how to define bilinear elastic-plastic material with tangent modulus in it.

If you can spare your little time to answer, I'll be very grateful. Thank you

 

[Dave442]

Hi SteveFinnan,

You can define your bilinear elastic plastic material model as follows:

*MATERIAL,NAME=STEEL
*DENSITY
7800,
*ELASTIC
193e+09, 0.27
*PLASTIC
207e+06, 0
UTS,UPS

UTS = ultimate tensile strength and UPS = ultimate plastic strain

The tangent stiffness describes the slope of the stress-strain curve between yield and failure. So if you specify a suitable value for the ultimate plastic strain you can work out the corresponding ultimate tensile strength from the tangent stiffness. Also, when your specifying the ultimate tensile strength and ultimate plastic strain, true stress and true plastic strain values must be used.

Good luck,
Dave