This paper on "Engineering Design Using Evolutionary Structural Optimisation Based on Iso-Stress-Driven Smooth Geometry Removal" was presented at the NAFEMS World Congress on The Evolution of Product Simulation From Established Methods to Virtual Testing & Prototyping - 24-28 April 2001, The Grand Hotel, Lake Como, Italy.

Abstract

The main goal of Evolutionary Structural Optimisation (ESO) research has been to provide an easily applicable optimisation method for the engineering industry which assists the design process for product improvement. Originally ESO was based on the concept of fully stressed structures and it is obtained by slowly removing, from a Finite Element mesh, the elements that present the lowest stress value. Following this heuristically-driven removal criterial the initial topology evolves towards the optimum one. Since its introduction in 19921 ESO has been developed and extended to several types of structural problems. Initial weaknesses of ESO were (i) typically long solution times and (ii) topologies with jagged surfaces as a result of removing whole elements in the optimisation process. These characteristics hindered its application to computer aided design and analysis. In this investigation, these weaknesses have been addressed for 20 situations by (i) basing the stress computation on the Fixed Grid (FG) finite element method and (ii) removing material with the lowest values along iso-stress contours instead of removing whole elements. A boundary representation (B-rep) of the structure is maintained at each iteration of the optimisation process. Modification to the workpiece is made by identifying the stress contour lines and incorporating them into the evolving geometry. The topological consistency of the B-rep is maintained via regularized 2D boolean operations.