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This is Fig. 15 of the 2005 PANDA2 paper. Shown here is the STAGS prediction for a shell previously optimized as imperfect by PANDA2. (Case name = testax4).
Shown here is the general buckling mode from a STAGS model of the optimized stiffened and sub-stiffened cylindrical shell (optimized by PANDA2 as imperfect but perfect in this STAGS model) under the same combined axial compression, external pressure, and in-plane shear listed in the caption two slides ago.
The sub-stiffeners are smeared, the major stiffeners are shell units, the STAGS 480 finite element is used.
This is bifurcation buckling mode 1, buckling load factor, Pcr = 1.4468 (general buckling). Pcr is significantly greater than 1.0 (the design load factor) because the shell was optimized by PANDA2 including the effect of a general buckling modal imperfaction whereas this slide shows the critical general buckling mode obtained from a model in which the same shell is perfect.
The purpose of obtaining STAGS predictions of this sort is to obtain a general buckling modal imperfection shape to be used in a subsequent nonlinear static equilibrium analysis by STAGS.
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