Decomposition method for coupled system reliability-based multidisciplinary design optimization

To reduce the computational cost of Reliability-based Multidisciplinary Design Optimization (RBMDO), a novel decomposition method oriented to coupled RBMDO was presented. Function Cost Table (FCT) was defined to tackle the randomness of reliability functions, and the computational method for FCT cost based on randamness characteristics of reliability functions was presented. Coupling Dependency Table (CDT) was also defined to cope with the coupling relationship between function, and an algorithm to identify and decompose the coupling variables was presented. Moreover, the measurement method for evaluation index of total computational cost was improved based on the information provided by FCT and CDT. Genetic algorithm was applied to obtain the minimal total computational cost decomposition solution. This method was verified by an electronic packaging RBMDO problem. Compared to two existing decomposition solutions, this method significantly reduced the total computational cost. Compared to traditional approach, this method had two advantages: on one hand, the coupled variables could be identified and decomposed so that it could be used for the coupled system decomposition; on the other hand, reliability functions were decomposed into average various sub-tasks to obtain less cost of the overall computation.