Abstract
PANDA is an interactive program through which minimum weight designs of composite, elastic-plastic, stiffened, cylindrical panels and complete cylindrical shells can be obtained subject to general and local buckling constraints and stress and strain constraints. The panels or shells are subjected to arbitrary combinations of uniform in-plane axial, circumferential, and shear loads. Nonlinear material effects are included if the material is isotropic or has stiffness in only one direction (as does a discrete or smeared stiffener). The panel can be stiffened with both stringers and rings. Several types of general and local buckling modes are introduced as constraints in the optimization process, including general instability, panel instability with either stringers or rings smeared out, local skin buckling, local crippling of stiffener segments, and general, panel, and local skin buckling including the effects of stiffener rolling. Certain stiffener rolling modes in which the panel skin does not deform but the cross section of the stiffener does deform are also accounted for. The interactive PANDA system consists of three independently executed modules, BEGIN, DECIDE, PANCON, that share the same data base. In the first module, BEGIN, an initial design concept and rough (not necessarily feasible or accurate) dimensions are provided by the user in a “conversational” mode. In the second module, DECIDE, the user decides which of the design parameters of the concept are to be treated by PANDA as decision variables in the optimization phase. In the third module, PANCON, the optimization calculations are carried out with the help of the well-known optimizer CONMIN.
Published Version
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