Analysis of a Standby System with Dissimilar Components and Imperfect Repair

Operating systems do not perform their intended functions as time passes and ultimately fail due the failure of one or more of their parts, units, or components. Failure is caused by many factors such as age, deterioration, wear and tear, leakage, and lack of proper and timely maintenances. Failed components are usually replaced if not expensive or critical; otherwise repaired. Repair can be perfect, minimal, or imperfect; the selection of a specific repair option is dependent on the desire of the decision maker and the capability of the repairing staff/facilities. In this paper, imperfect repair is applied where a failed component is repaired several times before complete replacement. The system in this study consists of two dissimilar (non-identical) components, one in operation and the other in cold standby; each component has a different failure and repair rate depending on time spent in operation. The performance of the system is measured using steady state availability. A numerical example is presented to illustrate and compare the performance and cost of two versions of the system, the first version with two dissimilar components, and the second with two similar and new components.