Differential evolution approach to reliability-oriented optimal design

• This research investigates the use of differential evolution algorithm to broaden the applicability field of the one-level KKT method in RBDO.
• The proposed approach removes the difficulty of taking the gradient of the second optimality condition, which implicitly assumes the existence of the second order derivatives of the limit state functions.
• Challenging numerical examples for which traditional optimization techniques are unfeasible become tractable.

The adoption of an evolutionary optimization approach, to tackle Reliability Based Design Optimization (RBDO) problems for which classical optimization is not feasible, can potentially lead to expand the use of RBDO in engineering applications. The herein proposed novel approach consists of coupling a differential evolution strategy with the one-level reliability method based on the Karush–Kuhn–Tucker (KKT) conditions. By selecting a few significant examples from the literature, convergence is found within a number of iterations compatible with the current capabilities of standard computational tools. These examples are chosen because lack of convergence is reported in literature when adopting classical gradient-based methods coupled with the reliability assessment. The performance and the efficiency of the algorithm are discussed, together with possible future improvements.