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Force to close a

Re: Force to close a

Same way.

Re: Force to close a

Hi!

I used an elastoplastic material, but obtain this warning message with high stress

Re: Force to close a

Please show more views of your model.  Is there a location with a sharp inside corner like this?

 

All inside corners near areas of interest should have at least a small radius.  For the plastic parts I work with 0.15mm radius is used.  Compared to H-elements, P-elements are less forgiving.  In H-elements the stress is averaged over the element size which hides the singularity until using smaller and smaller elements.  For P-elements the order of the element captures the high stress with larger elements.  You can artificially limit the order of the elements near singularities but I prefer a tiny, but realistic radius.

 

What strain is it reporting vs. what you expect?  Are you using a force or an enforced displacement.  With a force this same message often comes when the design cannot reach the load applied, sometimes even failing to finish the loadsteps.  I also suggest to plot a measure of plastic strain or stress vs loadstep.  You can stop the analysis and view intermediate results at each loadstep.

 

Finally element quality/number will affect the ability to model large strains.  A mapped mesh with quads and more layers through the thickness will help capture larger strains without too much element distortion.  A tetra mesh with large elements could contribute to the issue.

stress_riser.PNGstress riser

 

Re: Force to close a

Hi, 

I try to improve my model, but I obtain again high stresses;

I added a small radius where the displacement occurs and mapped mesh

Re: Force to close a

modulus.JPG

Re: Force to close a

Re: Force to close a

no

tan_mod.JPG

Re: Force to close a

In this way the values  of stress down, but there is again the warning

"** Warning:
The stress is much higher than the yield strength of one of the
elasto-plastic materials in your analysis. Please review
your material properties and/or units."

Re: Force to close a

wrong.JPG

Re: Force to close a

Where did you find this value (1000)?

The data sheet I mean.

Thanks

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