Bi-objective optimization of the reliability-redundancy allocation problem for series-parallel system

•We present a bi-objective reliability-redundancy allocation problem.•Reliability is considered as a triangular fuzzy number.•Linear and nonlinear membership functions are used for defining their fuzzy goals.•Preferences of DM corresponding to each objective have been incorporated.•PSO algorithm has been utilized to solve the optimization problem.

The main objective of this paper is to solve the bi-objective reliability redundancy allocation problem for series-parallel system where reliability of the system and the corresponding designing cost are considered as two different objectives. In their formulation, reliability of each component is considered as a triangular fuzzy number. In order to solve the problem, developed fuzzy model is converted to a crisp model by using expected values of fuzzy numbers and taking into account the preference of decision maker regarding cost and reliability goals. Finally the obtained crisp optimization problem has been solved with particle swarm optimization (PSO) and compared their results with genetic algorithm (GA). Examples are shown to illustrate the method. Finally statistical simulation has been performed for supremacy the approach.