Plastic Material Bilinear Setup

[Lee.Conti]

Hi,

I am modeling a nonlinear material using bilinear.

It is a plastic material where stress is dropping after yield point and modulus given in the specification is secant modulus NOT tangent modulus (initial best straight line).

I wanted to know for the ANSYS bilinear input below:

Modulus: Should I use tangent modulus or secant modulus (usually use this for linear properties)

Yield Strength: Should I use the stress point at the end of best straight line or yield point (usually use it for linear properties)

Tangent modulus: Should the tangent modulus be calculated based on engineering stress/strain or true stress/strain?

Thank you!

 

[Petr Vymlatil]

Hi Lee.Conti,

first you should decide if you need to define your stress-strain curve using engineering or true stress-strain curve. I doubt that you will see drop after yield point in the true stress-strain curve. If you are going to activate large-deflection (large rotation) effects or large strain effects (NLGEOM,ON), you must use true stress-strain curve.

After that, think how you approximate your true/engineering data with bi-linear plastic model.

Regards,

Petr



Petr Vymlatil (

http://www.designtec.eu)