814. Structural Optimization – A Dream or a Reality?

Paper

Abstract

The concept of designing optimal structures is not new. Since the start of the present century many attempts have been made to develop rational approaches to optimal design with varying degrees of success. One major obstacle to satisfactory progress was the recognition that optimization represents a degree of computational complexity above direct analysis, which in itself can be a problem lacking a complete solution. The phenomenal development of the digital computer has brought many hitherto feasible but computationally impractical analytical techniques into everyday use. This has reduced the analysis problem to manageable proportions and at the same time permitted a degree of refinement totally unrealizable in the past. This fact alone has brought the prospect of true optimum design nearer to hand. A definition of structural optimization in its broadest sense is that it is a process of finding that structural design which, subject to a specified environment, set of loading actions and design constraints, is the optimum structure corresponding to some previously defined criterion of merit. The merit criterion will frequently be weight in the aerospace industry, but may also be cost effectiveness, thermal insulation efficiency or any other quantifiable measure or combination of measures appropriate to the purpose of the design. This definition embraces all parameters involved in the design including structural configuration, geometry, materials, member sizes, etc. The present state of the art shows a diversity of approaches to the problem. These range from straightforward enumerations of a number of possible designs and selection of that with the greatest (or least) ‘merit’ to the systematic and automatic redesign of a given configuration to achieve the greatest (or least) ‘merit’.
Development of optimization technology has now advanced beyond the stage of conceptual investigation. An operational capability now exists which can be used effectively by the engineer both at the project design and detail design levels. The present and future roles of optimization in the design process are discussed, along with a presentation of some current work in this field.