PANDA2 finds minimum weight designs of laminated composite flat or curved cylindrical panels or cylindrical shells with stiffeners in one or two orthogonal directions. The panels or shells can be loaded by as many as five combinations of in-plane loads and normal pressure. Constraints on the design include crippling, local and general buckling, maximum tensile or compressive stress along the fibers and normal to the fibers in each lamina, and maximum in-plane shear stress in each lamina. Local and general buckling loads are calculated with the use of either closed-form expressions or discretized models of panel cross sections.

An analysis branch exists in which local post buckling of the panel skin and stringers are accounted for, meaning that the panel can be intentionally optimized to permit local buckling at a load less than the design load. In this branch a constraint condition that prevents stiffener pop-off is introduced into the optimization calculations.

The PANDA2 system includes two processors, PANEL and PANEL2, that can be used to create valid input files for BIGBOSOR4, and a processor, STAGSUNIT, that can be used to create valid input files for STAGS. Therefore, an optimum design first obtained by PANDA2 can be evaluated rather easily by then running BIGBOSOR4 and/or STAGS with automatically-generated valid input data corresponding to the optimized design developed by PANDA2.

Graphic showing Objective vs Iterations for Superopt

Graphic from AIAA 48th Structures, Structural Dynamics, and Materials Conference, Paper no. AIAA-2007-2216, 2007.

Design iterations during an execution of SUPEROPT, a PANDA2 processor the purpose of which is to seek a “global” optimum design. Each “spike” in the plot corresponds to a new starting design, which (as explained in [1D, 1K]) is generated randomly in a manner consistent with all linking and inequality constraints. See Table 3 for a typical PANDA2 runstream that includes several executions of SUPEROPT.

For a gallery of the kind of problem that can be solved by PANDA2, see the following three slide shows: Slide Show (1987-1995), Slide Show (1996-1999), and Slide Show (2002-2007). These three slide shows are primarily composed of pictures taken from the long, illustrated abstracts of papers about PANDA2 and results generated from executions of PANDA2 with verification of optimum designs produced by PANDA2 via execution of STAGS.

Abstracts and Papers (1987-1995)

Abstracts and Papers (1996-1999)

Abstracts and Papers (2002-2007)

Unpublished Papers