Plastic strains as initial condition in ABAQUS causing reduction in strength

[Gov45]

Hello All

In my ABAQUS simulation, I initialize the model with plastic strains and thickness data from forming simulation and use this data for buckling load simulation in ABAQUS.

When I do the buckling load simulation, the model in which plastic strains and thickness data is initialized shows higher load carrying capacity due to initial plastic strains which causes strain hardening effects.

But in one case the load carrying capacity has dropped by 2 kN after initializing the plastic strains and thickness.

My question is can initial plastic strains (40-50 % plastic strains)cause a reduction in load carrying capacity?

With Best Regards

 

[SWComposites]

If the thickness decreases, then yes.

 

[Gov45]

Thanks for the reply @SWComposites.

Yes there is a drop in thickness.
So I tried three cases

--> only thickness data from forming mapped - model A
--> only plastic strains from forming mapped - model B
--> no data mapped on model - model C

When I did the simulation for three cases

model A buckling load 73.2
model B buckling load 73.4
model C buckling load 74

Because of thickness reduction, buckling load dropped from 74 to 73.2 kN

But my concern is why the buckling load dropped from 74 to 73.4 kN in model B, there is no thickness mapped in model B.

Why the initial plastic strains are causing the drop in buckling load?
According to theory, the plastic strains should cause strain hardening but in my case (model B) the strength is dropping

 

[FEA way]

Aren’t you using the import functionality for this ? It’s meant for such cases and automatically transfers the deformed mesh along with the state of material.

 

[Gov45]

No @FEA Way,

I do forming simulation in a different software, converts the output of forming simulation to LS Dyana format and in ANSA I merge the LS Dyna file with ABAQUS input file and then do the Plastic strain and thickness mapping.

But, there is no question of mapping here as the mapping is 95% accurate

Question is why the initial plastic strains are causing the drop in buckling load?

 

[SWComposites]

hard to say without some pictures of the part and model.
please post deformed geometry plots for the buckling mode shapes for models A, B and C.

 

[FEA way]

Can you share the Abaqus .inp file(s) ?

Your workflow is quite complex. Can’t this forming process be simulated in Abaqus ? Are there specific features needed that Abaqus can’t provide but more specialized software can ?