More Membrane questions

FatmacFatmac
I'm finding more use for membrane elements and recently I have been getting some success in using them in the belts running around sheaves. I have seen mention of potential bugs in Calculix with these elements, can any one point me to where I could find more info about these bugs? I have noticed some odd differences in MW output when using membrane elements. I imagine that in calculix, membrane elements are expanded into solids like shell elements are. However the output from MW makes me question this. I attached a simple test that, I hope, illustrates


my point. In the case of the membrane results, the output shows only a 2d film, not a 50mm thick sheet as in the shell analysis. (also I see the shell bending more smoothly than the membrane). My other observation is that generally the membrane analysis takes longer. My questions are - have I set up the membrane elements correctly? and if so is the representation in MW suggesting that membrane elements remain 2d in the analysis?

Comments

  • FatmacFatmac
    here is the file
  • FatmacFatmac
    here
  • disladisla
    Membranes can’t sustain bending . In a bending test you would expect a V shape compared to the U delivered by a regular shell.
    To see the expansion add NODE FILE OUTPUT 3D option




  • FatmacFatmac
    Thanks Disla for pointing that out - it felt a little odd that the membrane required a 3D option and the shell did not. Now I see the expansion, it gives me more confidence that I am setting the membrane elements up correctly. it is interesting to see how the elements behave with the membrane having 2 nodes at junctions with other elements
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