Two-unit system subject to effective random shocks and preventive maintenance

This paper considers a two-unit system. The operating unit is subject to random shocks and preventive maintenance. The shocks occur at random times which follow a general distribution. The failure, repair and preventive maintenance times of the operating units are exponentially distributed. The mean time to system failure is obtained and how it is affected by random shocks and preventive maintenance is investigated. For both the systems, the graphs of Mean Time to System Failure (MTSF) are drawn against the shock rate for various values of the coefficient of variation of the shock time having K-Erlang distribution. From the graph, it is concluded that MTSF is inversely proportional to Coefficient of Variation (CV) of the shock time.