Dynamic reliability analysis of mechanical components based on equivalent strength degradation paths

摘要

Owing to the randomness of load applied to mechanical components, it is difficult to accurately determine the strength degradation path. Therefore, the distribution of strength at each load application is always used to deal with the uncertainty of strength in its degradation process, which may cause errors in reliability calculations due to neglecting the correlation with the remaining strength at each load application in a strength degradation path. To deal with this problem, dynamic reliability models of mechanical components with the failure mode of fatigue are developed in this paper, based on equivalent strength degradation paths, whose uncertainty is determined by both the distribution of material parameters and the distribution of load. The proposed models can be used to quantitatively analyse the influences of the variation in statistical parameters of material parameters on the reliability and failure rate of components. Explosive bolts, which are important to the successful launch of satellites, have been chosen as representative examples to validate the effectiveness and accuracy of the proposed models. The results show that using strength distribution at each load application may lead to large errors in calculating reliability. Moreover, different material parameters have different influences on dynamic characteristics of reliability and on the failure rate of mechanical components.