Multi-objective optimization in reliability based design

This paper discusses the development of a reliability-based multi-objective design tool for solving structural optimization problems. The developed design optimization tool has the capability to take into account the effects of variability on the proposed design through a user specified reliability design criterion. The nonlinear goal programming method used, provides for a design method that eliminates the difficulty of having to define an objective function and constraints, while at the same time has the capability of handling rank ordered design objectives or goals. In this work, multiple design criteria including structural weight, load induced stress, deflection, and mechanical reliability are considered. For simulation purposes the design of a pressure vessel cover plate was undertaken as a testbed for the developed design tool. The formulation of this structural optimization problem into goal programming form is presented. The resulting optimization problem was solved using Powell's conjugate directions method. Some numerical test cases are included demonstrating the design tool's capabilities as it applies to this design problem.