关键词: 运行过程, 超远航装备, k/n系统, 预防性维修, 更换准则

Abstract: Super-voyage equipment refers to gear designed for journeys covering vast distances and extended durations, such as crewed spacecraft and space stations. As human society advances, exploring the cosmos or uncovering uncharted territories has become inevitable. However, in practice, the reliability of current super-voyage technology remains immature. For instance, in 2024, a technical malfunction in a certain spacecraft left astronauts stranded on the International Space Station, primarily due to partial propulsion system failures compounded by a nitrogen leak. This underscores the critical importance of ensuring high reliability in such equipment throughout the entirety of their missions. Preventive maintenance refers to a series of maintenance activities carried out before a system failure occurs, aimed at enhancing system reliability and reducing economic losses caused by potential breakdowns. Due to its scientific rigor and effectiveness, it has attracted considerable attention from numerous scholars. This paper focuses on preventive maintenance research for k/n systems, as the core subsystems of super-voyage equipment—such as the control system, engine system, and propulsion system in a certain spacecraft model—are typically designed using a k/n configuration. However, research on preventive maintenance for k/n systems during operational processes remains insufficient at present. Therefore, to effectively prevent failures in the k/n systems of super-voyage equipment during operation, this paper proposes a preventive maintenance model for such systems tailored to their operational processes, building on existing research. First, by thoroughly considering the operational process, a basic preventive maintenance model for the k/n systems of super-voyage equipment based on their operational period is constructed, and the optimal number of components is determined analytically. Subsequently, to balance economic efficiency and maintainability, an optimized preventive maintenance model based on a replacement first criterion, as well as one based on a replacement last criterion, are proposed for the k/n systems of super-voyage equipment. The optimal number of components and the optimal scheduled replacement time are obtained through analytical methods. To verify the correctness of the analytical results, detailed numerical analyses are provided for each optimal solution. The numerical analysis reveals that when traditional models, which do not account for system operational duration, are applied, the resulting optimal number of components is minimized, making it difficult to effectively prevent system failures during operation. In the basic model section, calculations using conventional models—which also neglect operational duration—yield the smallest optimal number of components. Generally, a higher number of components enhances the reliability of a k/n system. By disregarding operational duration, the optimal component count is minimized, consequently reducing system reliability to its lowest level. For instance, when the operational duration is tx=0.4 and c1=10.0, the optimal number of components n* is 10, indicating that the system should be designed as a 2/10 configuration. However, if calculated using traditional models, n* becomes 8, resulting in a 2/8 system design. Compared to the 2/10 configuration, this reduces reliability and undermines the ability to prevent failures during operation. This finding demonstrates that the proposed model is more effective and scientifically robust than traditional preventive maintenance approaches. Finally, a case study on the preventive maintenance of a specific spacecraft's control system is conducted to illustrate how the proposed model can be used to derive the optimal maintenance strategy for a k/n system. As the "nerve center" of a spacecraft, the control system handles core tasks including attitude adjustment, orbital maneuvers, and communication management, making it crucial for ensuring flight safety and mission success. Any minor failure within the control system could trigger a chain reaction, leading to catastrophic consequences. Therefore, preventing failures in a spacecraft's control system during operation is of paramount importance. However, the numerical analysis indicates that traditional preventive maintenance methods are insufficient for effectively preventing failures in a k/n system during operation, whereas the new model proposed in this paper can successfully address this issue. Based on the actual situation, the optimal maintenance strategies for three scenarios are analyzed. The preventive maintenance model for the k/n system of super-voyage equipment oriented to the operational process, as proposed in this paper, can provide decision-makers with a scientific basis for enhancing the reliability of such systems during operation. However, the object of this study is crewed super-voyage equipment. For uncrewed super-voyage equipment carrying cargo, repairs cannot be performed on the system during its mission. Therefore, an in-depth analysis of preventive maintenance issues for this type of equipment represents a promising direction for future research.

Key words: operation duration, super-voyage equipment, k/n system, preventive maintenance model, replacement principle