redundancy allocation problem with a mixed strategy for a system with k-out-of-n subsystems and time- dependent failure rates based on weibull distribution: an optimization via simulation approach

Reliability improvement for electronics and mechanical systems is vital for engineers in order to design of these systems. for this reason, there are many researches in this scope to help engineers in real world applications. one of the useful methods in reliability optimization is redundancy allocation problem (rap). in the most previous works, the failure rates of system components are considered to be constant based on negative exponential distribution; whereas, nearly all systems in real world have components with time-dependent failure rates; i.e., the failure rates of system components will be changed time by time. in this paper, we have worked on a rap for a system under k-out-of-n subsystems with time- dependent components failure rates based on weibull distribution. also, the redundancy policy of the proposed system is considered as mixed strategy and the optimization method was based on the simulation technique to obtain reliability function as implicit function. finally, a branch and bound algorithm has been used to solve the model, exactly.