Shape design sensitivity analysis and optimisation with an existing associative CAD system

Abstract

In this paper, a new approach to shape design sensitivity analysis and optimisation of mechanical components is proposed. The approach draws upon the capabilities offered by state-of-the-art associative modelers to provide for shape design parameterization and design velocity computations, and uses a commercial finite element code for performance analysis and adjoint computations. The material derivative concept of continuum mechanics and a domain method of shape design sensitivity analysis are used for design sensitivity computations. The approach makes shape design optimisation a practical design tool bringing closer design, analysis, and manufacturing. The integrated design environment allows designers to create models that capture design intent, create finite element meshes for finite element analysis, perform geometric as well as performance what-if studies, modify design to improve performance, and generate 2-D production drawings at any design iteration. A number of approaches have been proposed during the last years for shape design parameterization. The ability to obtain an improved or optimal shape has been hindered so far by the ability to couple the analysis model with the design model. The earliest proposed approach used the position of the boundary nodes as design parameters, Zienkiewicz and ~am~belll. The method presented some severe drawbacks, as pointed out by in^^. Furthermore, as design variables were assigned to nodes on the moving part of the boundary, the number of design variables becomes very large leading to high computational effort. Also, undesirable shapes may result due to difficulty in ensuring boundary slope continuity. Since only boundary nodes move, it is difficult to maintain finite element mesh during the optimisation process.