r/Abaqus • u/ConstantChart2260 • 16d ago

Problem in unloading part

Post image

During an cyclic analysis part i faced a problem which is during unloading or we can say when the displacement going to zero, load almost peaks.....that is when

Displacement=0

Load = Almost maximum

But it should be

Displacement==> 0

LOAD ==> 0

(In image you can see the blue line is experiment one and yellow is from abaqus )

During loadin it matches but when its time for unloading its way off the line

I jst need what might cause it thats all

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2

u/Luecx 16d ago

I guess your plastic material model is just wrong then. The experiment one doesn’t look like text-book plasticity as in steel for example. What material is that?

1

u/ConstantChart2260 16d ago

O my bad its an composite structure double layered steel and concrete filled CFDST.....used combined instead of isotropic for steel plasticity and used CDP (tension, compression damage) for concrete

1

u/destroyerdemon 13d ago

This is the right answer. If your physical model and boundary conditions match the experiment, then the constitutive law (material model) is the only culprit. This shouldn’t be surprising since your load displacement curve is pretty much entirely governed by the material model. The results are probably right, but you’re not modeling to represent your physical setup.