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Post buckling response for tube collpase.

Post buckling response for tube collpase.

Post buckling response for tube collpase.

(OP)
Hi,

I have been working on a model of a tube with external pressure applied to it in ANSYS WB v11.0. The objective of this analysis was to figure out the value of lateral external pressure at which the tube will collapse. The ends of the tube are fixed and the tube has external hydrostatic pressure acting on it.

Using the first mode shape from a linear buckling mode analysis, a geometric imperfection was given to the tube so that collapse can be initiated. When a non-linear analysis was carried out on the tube using a bilinear isotropic hardening material model & large deflection turned ON, the deflection of the tube increased by a large amount for a small increment in applied load once the bifurcation point was reached indicating the onset of collapse. But, it is the post buckling response that I am having trouble capturing.

1) I tried refining the mesh & making the load steps smaller but it got to the point where it took 12 hours for the run and it still could not capture the post buckling response.
2) I tried adding artificial damping & using the ARCLEN method, but that did not help either.

So I was wondering if anyone here has successfully captured the post buckling response of a tube with external pressure. Any command or setting that I can use to capture the highly nonlinear load-deflection curve?

Thanks,
Mike

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