Stresses at Integration Points using S4 elements

[isma82]

All,

I have modelled using shell elements s4 a simply supported beam that has acting on it a uniform pressure load of 5N/mm2.

The dimensions of the beam are 10 mm with, 10 mm thick, and 100 mm long.

I am confused about the outcome of the stresses at the integration point of the elements. I attached a plot where I compared the integration point stresses, nodal stresses and hand-calculated stresses.

Does anyone understand the shape of the plot?

Thanks.

 

[Drej]

Confused how?

Given that your mesh is probably far too coarse for this problem, it looks perfectly reasonable. The integration point stresses are extrapolated to the nodes and then, depending on your settings, smoothed across elements (giving "element nodal values").

If this is a slender beam-type problem (given your dimensions it would certainly qualify as such), then use beam elements instead.

More importantly, refine your mesh and watch the stresses converge.




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[Drej]

One more thing - end effects. Your hand calc presumably assumes zero stress at the ends but presumably there is some constraint condition in the model, giving the difference between the two.


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