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 of electronic and mechanical systems is vital for engineers in order to design these systems. For this reason, there are many researches in this area to help engineers with real-world applications. One of the useful methods in reliability optimization is Redundancy Allocation Problem (RAP). In most previous related works, the failure rates of system components are considered to be constant based on negative exponential distribution, whereas nearly all real-world systems have components with timedependent failure rates; in other words, the failure rates of system components will change from time to time. In this paper, we have worked on an RAP for a system under k-outof- n subsystems that have components with time-dependent failure rates based on Weibull distribution. In addition, the redundancy policy of the proposed system is considered as a mixed strategy, and the optimization method is based on the simulation technique to obtain the reliability function as an implicit function. Finally, a branch and bound algorithm has been used to solve the model exactly.