ABAQUS results regarding improvement of strength

[abc123ali]

Respected ABAQUS users, I worked on stuff regarding thin sheet plasticity for which I got results with increased yield strength. Regarding it I have these questions

1. When we work for thin sheets, the work of hardening making the thick metal converting to sheet is included in experimental process which in return increases the yield strength; area under the stress-strain curve upto yield point is enhanced. How the software ABAQUS include this affect or which algorithm of mathematical model it follow to perform work hardeing during thining of metal sheets practically?

2. Secondly, If the yield strength is increased in the output results of ABAQUS; it means that for the same value of yield strain in experimental tension test verified or bechmarked with ABAQUS for thick sheet, thin sheet has high value of yield stress so there must be a point before this strain in thin sheet ABAQUS analysis curve which is equal to the yield strength of the thick sheet; which has more yield strain compare to thin sheet for the same value of yield stress. So in this situation which factor decides the yield and fracture point? Is thin sheet more vulnerable to yielding because of high values of yielsd stress and may it fracture earlier than thick one; as it attains value of fracture strength or UTS with less strain compared to the simple fracture strength tension test along with thick sheet fracture using experimental procedure?

3. How to predict the accurate value of fracture strain and fracture stress for thin sheet using ABAQUS considering above? Will the strength increase on expense of resilence energy or which one is the deciding factor to measure the safety factor, failure and yielding point in this case: tensile stress or tensile strain?; for the same value of yield strain the yield stress for thin specimen is more than thick so if the yield point of the thick plate is reached than the same value of yield stress occurs at lesser value of strain for thin sheet so at that point will the thin plate reach its yield strength or just the calculted yield strength is hypothetical ?

Thanks for cooperation

 

[FEA way]

So you simulated thinning itself too ? By simulating the forming process in the way it's done in real life ? And then you loaded the thinned sheets with some operational loads ? Or was the workflow different ?

 

[abc123ali]

I havent simulated forming process. I just did it by modifying the thickness of gemetry. How can I simulate forming process in ABAQUS to match results with real life?

 

[FEA way]

Then you should definitely do it so that your simulations account for all the effects caused by manufacturing like residual stresses and so on. It's typically done in Abaqus/Explicit and then the results (deformed mesh with material state) are imported to Abaqus/Standard for regular analysis of operational loading and/or springback after manufacturing. There are quite a few examples of simulations of different metal forming processes in Abaqus documentation.

 

[SWComposites]

You will need to input the appropriate material properties for the amount of work hardening at a given post-forming thickness.

And your questions about properties of thin vs thick sheets and post-forming are not a FEA issue, but a strength of materials issue that needs to be sorted out outside of the FEM.