Genetic Algorithms as an Approach to Configuration and Topology Design

Abstract

The genetic algorithm, a search and optimization technique based on the theory of natural selection, is applied to problems of structural topology design. An overview of the genetic algorithm will first describe the genetics-based representations and operators used in a typical genetic algorithm search. Then, a review of previous research in structural optimization is provided. A discretized design representation, and methods for mapping genetic algorithm chromosomes" into this representation, is then detailed. Several examples of genetic algorithm-based structural topology optimization are provided: we address the optimization of cantilevered plate topologies, and we investigate methods for optimizing finely-discretized design domains. The genetic algorithm's ability to find families of highly-fit designs is also examined. Finally, a description of potential future work in genetic algorithm-based structural topology optimization is offered. 1 Introduction Our interest in this article is the generation of optimal basic configurations of designed artifacts, a process commonly known as conceptual design. We use a general optimization technique which is not tailored to any particular design domain. Specifically, the examples we provide are in the domain of structural topology optimization using genetic algorithm search (Goldberg, 1989). Genetic algorithms can be applied to many other classes of conceptual design problemsÑthese efforts intend to help determine the utility of genetic algorithms in conceptual design. 2 Genetic Algorithms Genetic algorithms (GA's) are an optimization strategy where points in the design space are analogous to organisms involved in a process of natural selection (Holland, 1975). Each organism is represented by a character string analogous to a chromosome, with each character position analogous to a gene and each character value analogous to an allele. These "chromosomes," each representing a possibly-optimal design, are created in generations, with offspring designs arising from parent designs. Child designs are created when parent designs, chosen from the best designs in a generation, group in pairs to produce offspring via genetic reproduction and crossover (Fig. 1). Infrequent, random mutations (Fig. 2) are then performed on individual alleles. These operations yield two new chromosomes which represent two new designs possessing traits from both parents.