Decision on Redundancy Allocation

Redundancy allocation is a decision that involves assessing and choosing where to locate additional components or subassemblies, above the minimum required for an existing system to operate, in order to promote the system’s reliability. Specifically, the field of multi-objective redundancy allocation has received several contributions since the 1970s and the combinatorial complexity of these problems has mainly encouraged researchers to develop search algorithms focused on the Pareto front definition, the most frequent approach in this literature. Finding a set of non-dominated solutions based on heuristics is a step that demands much computational effort to solve the problem. Despite these difficulties, the DM’s preferences should be evaluated in order to recommend a solution that represents the best compromise among the criteria considered, such as reliability, cost and weight. This chapter covers redundancy allocation problems from a multicriteria perspective. Therefore, basic concepts related to the typical criteria and tradeoff in redundancy allocation problems are presented and a brief review of the literature on MCDM/A redundancy allocation is given. To illustrate the MCDM/A approach for redundancy allocation, a decision model considering a standby system based on Multi-attribute Utility Theory (MAUT) is presented including the DM’s behavior to risk (prone, neutral and risk averse). The problem approached in this chapter involves a question about how to select a suitable maintenance strategy in order to evaluate the tradeoff between a system’s availability and cost, including experts’ prior knowledge to deal with the uncertainty of failure and repair rate parameters.