Parts stressed beyong the material UTS should break
Parts stressed beyong the material UTS should break
(OP)
In SolidWorks Simulation Premium 2009 sp 4.1 I am trying to analyse the effect of frame structures being subjected to impact by a large mass. I am using bi-linear elasto-plastic materials and getting good results but in some parts of the structure maximum stresses exceed the UTS, in the anylisis these members are still contributing to the strength of the structure whereas in reality they should break and take no further part. Does anyone know of a workable solution to achieve this?






RE: Parts stressed beyong the material UTS should break
With a solver such as is found in SW (implicit solver) elements cannot detach from one another. All you will get is continued deformation of the element when you reach plasticity.
As an analyst it is up to you do determine when a portion of the model has failed based on plastic strain. The model will not detach.
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
"Node news is good news."
RE: Parts stressed beyong the material UTS should break
Please tell if you have given this a go.
Regards
RE: Parts stressed beyong the material UTS should break
gfbotha, many thanks for your answer. My understanding of defining a multi-linear stress-strain curve is that it has to be monotonic so the stress value must increase with strain and can-not turn downwards. The best it could do is become horizontal, but this would not solve my problem as the elements would still be contributing strength.
RE: Parts stressed beyong the material UTS should break
Rob Stupplebeen
RE: Parts stressed beyong the material UTS should break
However, I don't understand why you need a visual of the failure. Are you totally collapsing something far beyond what would normally be considered failure? Generally unconstrained plasticity is the point at which a structure has totally failed and there is no point in going further.
TOP
CSWP, BSSE
www.engtran.com www.niswug.org
"Node news is good news."
RE: Parts stressed beyong the material UTS should break
If one is to try this out, I would not take the stress down all the way (to zero) and would consider displacement or arc-length control. Granted, convergence might prove more difficult.
Similarly one might also explore the NL elastic material model for a rough estimate - if true modelling of plasticity and behaviour during unloading is not important. With all the above I am assuming a first cut type of analysis where trends and order of magnitude are more important, also given your software limitations.
RE: Parts stressed beyong the material UTS should break
I will consider these and make some trials and respond later.
Regards to you all