Reliability evaluation and optimization of dissimilar-component cold-standby redundant systems

A new methodology for reliability evaluation and optimization of non-repairable dissimilar-component cold-standby redundant systems is introduced in this paper. Each component includes some elements with series-parallel configuration. When the operating component fails, the next dissimilar component is put into operation. Therefore, the initially functioning elements are backed up by one or more cold-standby redundant elements. The lifetimes of the elements are assumed to be independent random variables with Erlang distribution. The purchase cost of each element is assumed to be an increasing function of its expected lifetime. To evaluate the system reliability, we apply shortest path technique in stochastic networks. To do that, we construct a directed stochastic network called E-network, in which each path of this network corresponds with a minimal cut of the reliability graph. Finally, we construct a multi-objective problem and apply the surrogate worth trade-off method to solve the related problem and determine the optimal allocation of reliability to the elements of the system.