OPTIMAL REPLACEMENT OF AN ITEM SUBJECT TO CUMULATIVE DAMAGE UNDER PERIODIC INSPECTIONS

An item undergoes cumulative damage through use. The item fails random ly but the failure rate depends on the accumulated damage. The item is preventively replaced if it survives a certain damage limit at period ic inspections; on failure, it is replaced immediately. The optimal da mage limit for preventive replacement which minimizes the long-run exp ected cost rate is derived. It is unique if an item has increasing dam age-dependent failure rate. Numerical example for a stationary gamma p rocess with Weibull distributed failure is given. Copyright (C) 1996 E lsevier Science Ltd.