Replacement Policy for a Two-Unit System with Failure Rate Interaction and Shocks

• Main Authors: Chien-kuo Sung, 宋建國
• Other Authors: Tsung-shin Hsu
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/29231981061099442581

博士 === 國立臺灣科技大學 === 工業管理系 === 100 === This dissertation presents an extended replacement policy for a two-unit system that is subject to shocks and exhibits interaction of failure rates. The shocks were simulated using a non-homogeneous Poisson process (NHPP). There are two types of system shocks considered: (1) a Type I shock causes a minor failure of Unit A, and the damage that is caused by such a failure affects Unit B, and (2) a Type II shock which causes a total failure of the system (catastrophic failure). All Unit A failures can be corrected by making minimal repairs. The system also exhibits interaction among the failure rates of units; a failure of any Unit A causes an internal shock that increases the failure rate of Unit B, while a failure of a Unit B causes instantaneous failure of Unit A. Furthermore, the shocks occur according to a non-homogeneous pure birth process (NHPBP) is presented. The shock type is based on a random mechanism that depends on the number of shocks that have occurred since the last replacement. The goal of this dissertation is to derive the expected cost per unit time of replacement by introducing relative costs as a factor in determining optimality. The optimal replacement period (T*), the optimal number of Unit A failures (n*) assuming NHPP, and optimal age replacement policy assuming NHPBP which minimize that cost were determined.