International Society of Science and Applied Technologies 

Optimal Replacement Policies with Deviation Times for Cumulative Damage Processes  
Author  Xufeng Zhao


CoAuthor(s)  Lubing Wang; Satoshi Mizutani; Toshio Nakagawa


Abstract  In most studies of maintenance modeling, we should give assumptions of the costs for replacement policies, and then find the optimal policies to balance the expected costs before and after failures. However, when an operating unit degenerates with damage due to shocks, preventive replacement policies should be better done at some damage level Z before failure threshold K, even they are planned at time T or at shock number N. In other words, the total damage Z_{T} at time T and Z_{N} at shock N should be less than K. In our opinion, replacement policies cannot prevent the failure K perfectly and only the expected but not exact time T^{*}, shock number N^{*} and damage level Z^{*} are obtained. From the above viewpoint, we model replacement policies for cumulative damage processes to balance the expected deviations of time and damage level between the planned times of preventive and corrective replacement policies. Without considering the assumptions of costs, which are sometimes strong assumptions, we believe that it would be reasonable to construct replacement models from the point of deviation time and damage.


Keywords  Replacement policy, damage model, deviation time, failure threshold, reliability  
Article #: RQD2763 
Proceedings of 27th ISSAT International Conference on Reliability & Quality in Design 