On the consideration of uncertainty in design: optimization - reliability - robustness

Structural designs proposed by engineers aim to ensure that specific defined requirements are satisfied. Structural optimization is also widely used to identify an admissible design with optimal performance. However, it is important to remember that real mechanical problems exhibit uncertainties in practice that might entail challenges when searching for admissible and/or optimal design solutions. One objective of this paper is to discuss the possible formulations of design problems in this type of uncertain context. By considering uncertainties in the constraint and/or objective functions underlying design problems, several design strategies might in fact be implemented. Especially, this paper should contribute to clarifying the use of the concepts of robustness and reliability in design. After an introduction, the featured design strategies are illustrated and discussed via three academic examples which involve multiple random and design variables. Results show that the structural solutions obtained can be quite sensitive to the formulation of the problem. Thus, the latter should be considered as an essential step during the design procedure.