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This is Fig. 1 from the 1987 PANDA2 paper. This slide shows a single skin-stringer module of a panel with T-shaped stiffeners. The axial load, Nx, acts normal to the screen. The local buckling and postbuckling analyses are based on this single-module model. A wide-column simulation of general buckling is also based on this single-module model.
The single module consists of a number of segments. Each segment can have a different laminated composite (or simple isotropic or orthotropic) wall construction.
Typically, decision variables in an optimization can include the cross-section dimensions, b, b2, h, and w, and also thicknesses and layup angles of layers in each module segment.
While this and the next 3 slides show a panel with T-shaped stiffeners, the PANDA2 "stable" of stiffener cross section shapes also includes blade (rectangular) stiffeners, J-shaped stiffeners, Z-shaped stiffeners, hat-shaped stiffeners, and truss-core sandwich wall construction. I-shaped stiffeners are treated as T-shaped stiffeners with a faying flange.
PANDA2 can also handle optimization of sandwich panels in which several failure modes unique to sandwich wall construction are included as design constraints (design margins).
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