Hi friends! I propose the challenge from NAFEMS. On the WEB is possible to find a solution proposed by a British FEM specialist. I solved the problem and I achieved a good accordance with their FEA results. After that the solution proposed by the specialist is 231 KN/m2 (to the collapse). I stopped my simulation at about 200 KN/m2 and this is my proposed limit for the plate...maybe I'm too on safe!!!

Try to solve it.....

Try to solve it.....

pdf

pdf

Challenge_02_web.pdf

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## Comments

a) Boundary: perform linear static to know if boundary condition will affect the results. If boundary are iperstatic could affect the results in a different manner performing second order analysis. Sensitivity studies must be performed to find the better boundary

b) calibration against known values, when is possible

c) mesh convergence studies for stress analysis

d) time/load increment sufficient small (convergence study)

e) check the reaction

f) hourglass control for reduced integration (if used)

.......and other

In this case if one performs a static analysis locking vertical displacements of perimetral nodes will find a downward vertical reaction at the corner which is not real. How this affects the results?

If one use CCX with shell elements S8R must evaluate hourglass energy (must remains small)

If one use CCX S8 elements must know that this elements are expanded to a 20 nodes brick elements. So if one restraints a node of the shell this node is the middle node through thickness. Conceptually must be restrained the lower nodes. How this affects the results? For example is necessary to conduct a study adding OFFSET parameter to *SHELL SECTION

Gravity load: is it negligible?