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This is Fig. 9 from the 2005 substiff paper. This slide shows a STAGS model of the entire cylindrical shell. All major stiffeners and all sub-stiffeners are smeared. The STAGS 480 finite element is used.
Shown here is STAGS bifurcation buckling mode 1 for the optimized perfect shell. The STAGS buckling load factor, Pcr = 1.2883. Pcr = 1.0 is the design load.
Compare with the previous slide. Corresponding to that model, in which the major rings and major stringers were modeled as little flexible shell units, the buckling load factor, Pcr = 1.0511. Hence, in this case smearing the major rings and stringers leads to a prediction that is unconservative, perhaps unacceptably so.
This and the previous several slides demonstrate the various STAGS models that can be generated automatically by the PANDA2 processor called "STAGSUNIT", models of a shell that has previously been optimized by PANDA2.
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