I have a model under compression with large deflection. When I turn off stress-stiffening effects in PLANE42 elements by issuing "SSTIF,OFF", the solution converges. The solution does not converge with PLANE18X elements as they ignore the SSTIF command, regardless of element formulation used. Is it possible to modify the PLANE182 element to converge successfully in the same or in a similar pattern as PLANE42, all other things being equal?
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At 11.0SP1, "SSTIF,OFF,-1" will turn off stress stiffening effects in the 18X elements, even with "NLGEOM,ON". This will remain an undocumented feature. Users should be cautioned to use this option only as a last resort when all else fails (mesh refinement, element formulation options, nonlinear material testing). Inclusion of stress stiffness and pressure load stiffness gets you closer to tangent stiffness and are generally recommended. |
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