Reliability Allocation Method for Aircraft Mechanical Systems Involving Motion Performance and Failure Correlation

One of the most important design requirements for aircraft mechanical systems is to ensure that their motion functions can be executed smoothly. In this paper, an unconstrained reliability allocation method is proposed, taking into account the characteristics of aircraft mechanical systems. A decomposition principle for assessing the motion performance of aircraft mechanical systems has been proposed, and the contribution of each subsystem is analyzed. Weighting factors for system allocation are proposed and refined, and a failure correlation index is proposed to account for the influence of the interaction between subsystems on the potential failure rate. Furthermore, non-destructive failure events that could have a significant impact on motion performance have been taken into account in the potential improvement of subsystems. Subsequently, reliability prediction models of the systems are established using the Copula function, and a calculation method is introduced to distinguish and quantify the correlation between different subsystems. Finally, the applicability and validity of the proposed method are demonstrated through an engineering case. The results indicate that when failure correlation is considered, the reliability allocated to subsystems is significantly lower than that obtained using traditional methods, providing theoretical guidance for the reliability design of aircraft mechanical systems.