Hello
I have an FE model (linear elastic material, homogeneous) using shell181 elements. The structure is subject to constant acceleration and undergoes a static analysis (antype,static).
About shell,mid and keyopt(8), Ansys manual reports:
KEYOPT(8) = 2 stores midsurface results in the results file for single or multi-layer shell elements. If you use SHELL,MID, you will see these calculated values, rather than the average of the TOP and BOTTOM results. You should use this option to access these correct midsurface results (membrane results) for those analyses where averaging TOP and BOTTOM results is inappropriate; examples include midsurface stresses and strains with nonlinear material behavior, and midsurface results after mode combinations that involve squaring operations such as in spectrum analyses
My midsurface results are not the average of top and bottom results, despite linear material and static analysis.
Just as an example for one element, I have for Von Mises (PRETAB):
ELEM STOP SMID SBOT
41848 0.20593E+008 0.60772E+007 0.26821E+008
where SMID, Von mises at shell,mid location, clearly is not the average between top and bottom.
So, why is this behavior happening given that I have linear material and no response spectrum analysis?
For some more context - I am trying to review my simulations results and check whether some calculated high stresses go through the thickness of the shell elements or if they are mainly located at top/bottom. When I plot shell,mid in Ansys I get some results, quite low, see above one order of magnitude less than top/bottom. However, when I evaluate membrane stresses taking the average between top/bottom, then I get much higher results, for element above would be around 0.23E8.
Thanks in advance.
I have an FE model (linear elastic material, homogeneous) using shell181 elements. The structure is subject to constant acceleration and undergoes a static analysis (antype,static).
About shell,mid and keyopt(8), Ansys manual reports:
KEYOPT(8) = 2 stores midsurface results in the results file for single or multi-layer shell elements. If you use SHELL,MID, you will see these calculated values, rather than the average of the TOP and BOTTOM results. You should use this option to access these correct midsurface results (membrane results) for those analyses where averaging TOP and BOTTOM results is inappropriate; examples include midsurface stresses and strains with nonlinear material behavior, and midsurface results after mode combinations that involve squaring operations such as in spectrum analyses
My midsurface results are not the average of top and bottom results, despite linear material and static analysis.
Just as an example for one element, I have for Von Mises (PRETAB):
ELEM STOP SMID SBOT
41848 0.20593E+008 0.60772E+007 0.26821E+008
where SMID, Von mises at shell,mid location, clearly is not the average between top and bottom.
So, why is this behavior happening given that I have linear material and no response spectrum analysis?
For some more context - I am trying to review my simulations results and check whether some calculated high stresses go through the thickness of the shell elements or if they are mainly located at top/bottom. When I plot shell,mid in Ansys I get some results, quite low, see above one order of magnitude less than top/bottom. However, when I evaluate membrane stresses taking the average between top/bottom, then I get much higher results, for element above would be around 0.23E8.
Thanks in advance.
