Reliability Based Design Optimization for Multidisciplinary Systems Using Response Surfaces

Abstract

This paper investigates reliability based design optimization (RBDO) using response surface approximations (RSA) 1;2 for multidisciplinary design optimization (MDO). In RBDO the constraints are variational (reliability based) since the design variables and the system parameters can have variation and can be subjected to uncertainties 18 . For these problems the objective is to minimize a cost function while satisfying reliability based constraints. This class of problems is referred to as reliability based multidisciplinary design optimization (RBMDO) problems 5 . The reliability constraints, which can be formulated in terms of the reliability indices or in terms of the probability of failure, themselves represent an optimization problem and can be very expensive to evaluate for large scale multidisciplinary problems. Response surface approximations of the constraints are used in estimating the reliability indices or probability of failure when solving an approximate optimization problem using FORM. In this research RSAs are integrated within RBDO to significantly reduce the computational cost of traditional RBDO. The proposed methodology is compared to traditional RBDO in application to multidisciplinary test problems, and the computational savings and benefits are discussed.