Age Replacement Policies with Shortage and Excess Costs  
Author Mingchih Chen
Co-Author(s) Xufeng Zhao; Toshio Nakagawa
Abstract It has been proposed that if replacement time is planned too early prior to failure time, a waste of operation cost, i.e., excess costs, would incurr because the system might run for an additional period of time to complete critical operations, and if the replacement time is too late after failure, a great failure cost, i.e., shortage cost, is incurred due to the delay in time of the carelessly scheduled replacement. The above notion of shortage and excess costs of units are taken into considerations for replacement first and last models in this paper. That is, the unit is supposed to be replaced preventively at age T or at working time Y and works N, and the approaches of whichever occurs first and last are applied for models. We obtain the expected cost rates and their optimum replacement times. Comparisons of replacement first and last are also made analytically.
Keywords Shortage cost, working time, replacement last, age replacement, random replacement
    Article #:  23-079
Proceedings of the 23rd ISSAT International Conference on Reliability and Quality in Design
August 3-5, 2017 - Chicago, Illinois, U.S.A.