On the application of quasi-renewal theory in optimization of imperfect maintenance policies

This research applies quasi-renewal process to develop imperfect preventive maintenance models for aging systems. Due to the system failure and maintenance, the aging systems deteriorate during their life cycle and lead to "decrease of operation time" and "increase of maintenance time." Thus, after failure and/or maintenance, the system operating time, maintenance time, maintenance cost, and environmental factors will deteriorate. Using statistical analysis, the deteriorating parameters can be derived to facilitate the construction of more accurate availability and maintenance cost models. Based on the statistical analysis of failure and maintenance data, the failure distribution and availability models of aging systems can be constructed. Considering the "block" and "age" preventive maintenance policies, separately, the maintenance cost models are developed to minimize the maintenance cost rate. Using the numerical analysis, the optimal "block" or "age" preventive maintenance period can be solved. Finally, the optimal preventive maintenance policy can be obtained via the synthesis and analysis of different maintenance policies subject to the constraint of availability requirements. The results of this research can be applied to different equipment in the operational phase of the total life cycle. Collecting the field failure and maintenance data, the methods and procedures developed in this research can be applied to different equipment to analyze the preventive maintenance period for different policies to obtain the optimal preventive maintenance policy.