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STAGS model of nonlinear buckling of a ring and stringer stiffened axially compressed cylindrical shell previouly optimized by PANDA2

This is Fig. 61 from the 2007 Bushnell paper. Shown here is the nonlinear stringer bending-torsion buckling mode obtained by STAGS for the optimum design obtained by PANDA2.

This stringer buckling mode is used as a second buckling modal imperfection shape with amplitude, Wimp2 = -0.0005 inch in a subsequent nonlinear static STAGS run listed as Case 4 in Table 4 (previous slide).

This nonlinear stringer bending-torsion buckling mode corresponds to the load factor, PA = 1.07084. There is one imperfection shape in the STAGS model that produced the nonlinear stringer bending-torsion buckling mode displayed here: that shown 5 slides ago with amplitude, Wimp1=+0.0625 inch.

The nonlinear collapse load Nx(collapse) predicted by STAGS from the static nonlinear equilibrium of the model with the two imperfection shapes is
Nx(collapse)=1.1386 x Nx(applied)=1.1386 x 3000 lb/inch, in which 3000 lb/in is the design load used for the PANDA2 optimization and 1.1386 is the STAGS load factor, PA.

PANDA2 predicts 1.0097 x Nx(applied) for the stringer bending-torsion buckling mode of the imperfect shell as loaded by the design load, Nx(applied)= -3000 lb/in.

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