Sensitivity and optimization of composite structures in MSC/NASTRAN

The main purpose of this paper is to present the considerations and the resultant approach used to implement design sensitivity capability for composites into a large-scale, general-purpose finite element system (msc/nastran). The design variables for composites can be lamina thicknesses, orientation angles, material properties, or a combination of all three. As a secondary goal, the sensitivity analysis has been coupled with a general-purpose optimizer to validate sensitivity analysis results and also demonstrate how easy it is couple to an optimizer once a general senssitivity capability is available. This preliminary version of the optimizer is capable of dealing with minimum weight structural design with a rather general design variable linking capability at the element level or the system level. Only sizing type of design variables (i.e., lamina thicknesses) can be handled by the optimizer.
Test cases have been run and validated by comparison witj independent finite element packages. The linking of a design sensitivity capability for composites in msc/nastran with an optimizer would give designsrs a powerful, automated tool to carry out practical optimization design of real-life, complicated composite structures.