I am trying to use engineering stress-strain data for nonlinear modelling of the isotropic material in APDL. There is of course no problem in elastic region. In plastic region, we have strain hardening till necking followed by strain softening zone till rupture. But how do I exaclty know when softening starts? Does softening always starts after necking?
a) If No. How can I confirm the softening zone from engineering stress-strain curve?
b) If Yes, then I can simply change the engineering curve into true curve and use available hardening model till necking. Then what about softening? Well, I tried to use damage critetia to model the softening zone. As we know, it needs true stress-strain data as an input to find diffetent damage parameters. So, can we use the conversion relation beyond necking and find damage parameters?
Any suggestions are welcomed and Thank You in advance.
The conversion from engineering stress-strain to true stress-strain is commonly used in material modeling, especially for materials that undergo significant plastic deformation. However, the conversion has limitations, especially beyond the necking point. Let's address your questions and considerations:
The conversion from engineering to true stress-strain is most accurate up to the point of necking, but beyond that, it may not accurately represent the material's behavior, especially in the softening region. To model softening accurately, it's essential to have access to true stress-strain data or to use appropriate modeling techniques that consider the specific material response in the post-necking regime. Accurate characterization of softening typically requires additional experimental data or advanced modeling methods.
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