Imperfect Repair Strategies for Two-Dimensional Warranty

<p>When a repairable product under warranty fails, the manufacturer (warrantor) has the choice to either repair or replace the failed product. When repairing a failed product, the degree of repair which affects the working condition of the product can vary, and this is assumed to have an impact on the cost of the repair. The main motivation of this study is to develop a warranty repair strategy that minimizes the costs associated with servicing the warranty. In this research, the product coverage is represented by a two-dimensional rectangular region with a free-replacement warranty. We propose an imperfect repair strategy that suggests employing imperfect repairs of a predefined degree, in prespecified subregions of the warranty region. The aim is to then minimize the expected warranty servicing cost to the manufacturer by determining the optimal partitioning of the warranty region for the chosen degrees of repair. Two imperfect repair models are considered, and for both, the expressions for the distribution of the times to imperfect repair and the expected warranty servicing cost per product sold are derived. We numerically illustrate our findings and compare the expected costs of the proposed imperfect repair strategy with those of previously developed repair-replacement warranty strategies.</p>

Imperfect Repair Strategies for Two-Dimensional Warranty

<p>When a repairable product under warranty fails, the manufacturer (warrantor) has the choice to either repair or replace the failed product. When repairing a failed product, the degree of repair which affects the working condition of the product can vary, and this is assumed to have an impact on the cost of the repair. The main motivation of this study is to develop a warranty repair strategy that minimizes the costs associated with servicing the warranty. In this research, the product coverage is represented by a two-dimensional rectangular region with a free-replacement warranty. We propose an imperfect repair strategy that suggests employing imperfect repairs of a predefined degree, in prespecified subregions of the warranty region. The aim is to then minimize the expected warranty servicing cost to the manufacturer by determining the optimal partitioning of the warranty region for the chosen degrees of repair. Two imperfect repair models are considered, and for both, the expressions for the distribution of the times to imperfect repair and the expected warranty servicing cost per product sold are derived. We numerically illustrate our findings and compare the expected costs of the proposed imperfect repair strategy with those of previously developed repair-replacement warranty strategies.</p>

Imperfect Repair Strategies for Two-Dimensional Warranty

<p>When a repairable product under warranty fails, the manufacturer (warrantor) has the choice to either repair or replace the failed product. When repairing a failed product, the degree of repair which affects the working condition of the product can vary, and this is assumed to have an impact on the cost of the repair. The main motivation of this study is to develop a warranty repair strategy that minimizes the costs associated with servicing the warranty. In this research, the product coverage is represented by a two-dimensional rectangular region with a free-replacement warranty. We propose an imperfect repair strategy that suggests employing imperfect repairs of a predefined degree, in prespecified subregions of the warranty region. The aim is to then minimize the expected warranty servicing cost to the manufacturer by determining the optimal partitioning of the warranty region for the chosen degrees of repair. Two imperfect repair models are considered, and for both, the expressions for the distribution of the times to imperfect repair and the expected warranty servicing cost per product sold are derived. We numerically illustrate our findings and compare the expected costs of the proposed imperfect repair strategy with those of previously developed repair-replacement warranty strategies.</p>

Relations of Imperfect Repairs to Critical Infrastructure Maintenance Costs

This article presents an analysis of maintenance costs and maintenance policy of critical infrastructure systems, considering the case of imperfect repair. The maintenance costs of the systems, considering a multistate approach and imperfect repairs, are analyzed with reference to the renewal stream and renewal process theory. Availability characteristics of repairable critical infrastructure systems with non-negligible renovation time, necessary for the cost analysis, are determined based on classical renewal theory. We assume that the system is renewed after exceeding its critical reliability state. The multistate approach proposed to availability analysis, including imperfect repairs, allows considering various configurations of the system’s renewals. The procedure for determining the total cost of maintenance up to certain point in time is proposed. Furthermore, the procedure comparing the costs of repair and operation of the system until a certain moment for different configurations of the number of repairs to various reliability states is put forward and its exemplary application is presented. Conducting perfect renewals of infrastructure to the state of entire availability seems to be the most profitable in the case study analyzed in the article. The exception is when imperfect repairs are much cheaper than perfect repairs (they are up to half of the perfect repair cost), or when costs of an infrastructure’s renewals are considered in the short period of its exploitation (up to one year). The summary provides a conclusion on maintenance policy based on the proposed procedure analysis and a comparison of maintenance costs for various configurations of perfect and imperfect repairs.

System Maintenance Using Several Imperfect Repairs Before a Perfect Repair

Allowing several imperfect repairs before a perfect repair can lead to a highly reliable and efficient system by reducing repair time and repair cost. Assuming exponential lifetime and exponential repair time, we determine the optimal probability $p$ of choosing a perfect repair over an imperfect repair after each failure. Based on either the limiting availability or the limiting average repair cost per unit time, we determine the optimal number of imperfect repairs before conducting a perfect repair.