A three-dimensional shape optimization system—shop3D

Abstract

A modular approach for shape optimization of three-dimensional solid structures is described. A major consideration in the development of this capability is the desire to use a commercially available finite element program, such as NASTRAN, for analysis. Since NASTRAN cannot be called as a subroutine, a system architecture was developed of independently executable modules in which sequential execution is controlled by job control language. Also, shape sensitivities are not commonly available in commercial programs. A hybrid approach which is based on the material derivative concept is developed to obtain shape sensitivities by post processing finite element results stored on files. A quick generation of a good optimization model combined with an efficient optimization system will result in a drastic design time saving. In this paper, different modeling approaches for shape optimization are discussed. Emphasis will be placed upon a special modeling technique which overlays the design model onto an already existing finite element model. Several automotive related examples are used to evaluate the program's effectiveness.