A probabilistic feasible region approach for reliability-based design optimization

Reliability-based design optimization (RBDO) is a useful tool for design optimization when considering the probabilistic characteristics of the design variables. However, its use in practical applications is hindered by its huge computational cost during structure reliability evaluating process. Sequential optimization and reliability assessment (SORA) method is one of the most popular methods used for RBDO. In this paper, the proposed probabilistic feasible region (PFR) approach is based on the SORA framework, and it is developed to enhance the efficiency of SORA. In PFR, the notion of probabilistic feasible region is created using the reliability assessment results; Rather than conducting reliability assessment for every movement of the design variables, when the design variables locate in the probabilistic feasibile region during the optimizaiton iterations, no new relibility assessment will be needed. The range of the probabilistic feasible region is updated and becaome larger during the interaion processes, and its creation does not need extra computational cost. The computation capability of the proposed PFR is demonstrated and compared to the SORA method using a mathematical example, a speed reducer design and a box girder structure design application. The comparison results show that the proposed PFR approach is very efficient.