how nonlinear is the material?
are you sure it can't be approximated in a linear method?
i doubt you would lose that much accuracy
I do not know how non-linear is the material. I do know that I am using high load to reach area in the curve where the deformation are non-linear.
Do I need premium simulation for this?.
Should I concentrate on linear deformation and ensure that my design does not reach non linear stress/strain ratio?
Looking at the stress/strain graph the Yield stress is about 40MPa and the max stress in the linear zone is about 20MPa for average PP material.
The Simulation are showing the bucket collapsing with the wall going in a convex shape. The bucket in the test machine is going in a concave shape.
I would like to get a more realistic deformation. I only have simulation professional. I was wondering what can I do to get a more accurate simulation.
Also the loading of the bucket with 7000N is showing still a high margin to yield stress. The buckets collapse at 7000N and 60second.
I think the key is granting that you container will withstand the loads. I'd go for the worst conditions test.
About the deformation shape .....
Have you observed the real tests for a simple metal sheet loaded from two edges ?
There is no way for making a prediction about to which side the sheet is going to bend. Bulging is quite affected by the material anisotropy, and tiny differences in the fixing devices.
The key here is avoiding bulging. From my point of view, probably both shapes (convex and concave) are possible and accurate.
Constraint observation: it would appear from your analysis plot that the top "spreads out"; that is not the case in your in-situ, crush test. You should probably add some horizontal restraint to the top surface, perhaps with friction?
As @Txon states, whether concave or convex might be a process/material thing, i.e. buckling, where you can predict that it will happen but not exactly in which direction.
Have you tried contacting SABIC or Exxon directly to get the information you are looking for as to non-linear material properties?
The more I get into plastics FEA, the more I realize how difficult it is to get any accurate or even reasonable answers here...
If you're new to nonlinear world, I would suggest to start reading some fundamental things:
and so on...
There is very little linearity in plastics. As Txon already mentioned, one of the biggests misleadings is plastics is to assume they are isotrophic...If you investigate the plastics injection process, you will quickly realize how much the material properties can vary ie. due to orientation effect and lot's of other things.
If there are some assumptions and simplifications to be made regarding FEA for a steel structures, there will be even more for plastics.
I'm not sure what more you could achieve by obtaining a better stress-strain curve in this particular example..