An inspection strategy for randomly failing systems subjected to random shocks

This paper is motivated by the study of randomly failing systems whose state is only known through inspection and for which high availability is required. Security and alarm systems such as power system protective relays and environmental censoring equipment are typical examples of such systems. The deterioration process of these systems is generally governed by electromechanical transient shocks which occur randomly over time and whose magnitude is also random. These shocks damage the system cumulatively. Under the proposed inspection strategy, the system is inspected at predetermined times T₁, T₂, … . If failure is detected then the system is replaced by a new one, otherwise it is kept operating. The expression of the system time-stationary availability is presented and an algorithm has been developed to generate the inspection sequence which insures a certain availability level. In cases where limited resources restrict the user to predetermined inspection period, the computer program generates the optimal design and operating parameters which will provide the targeted system availability level. A test case is analyzed and potential applications related to automotive industries are mentioned