Dynamic reliability analysis of series mechanical systems considering strength degradation path dependence of components

Abstract

In this paper, dynamic reliability models of series mechanical systems in terms of stress parameters and strength parameters are established, in which strength degradation path dependence (SDPD) and failure dependence of components in the system are taken into consideration. Despite the computational convenience for reliability evaluation by using the independent strength distribution at each load application, large errors could be caused due to neglecting the existence of SDPD. In this paper, influences of SDPD on both dynamic system reliability and failure dependence are investigated. Moreover, the impacts of the dispersion of initial strength and the number of components in a system on the influences of SDPD on dynamic system reliability are analyzed. In addition, the clamp band joint system is used as illustrative examples to demonstrate the proposed models. The results show that SDPD have considerable influences, which vary in different operational stage of series mechanical systems, on dynamic system reliability and failure dependence. Besides, the dispersion of initial strength and the number of components have different impacts on the effects of SDPD on system reliability.

Reliability-Based Analytic Models for Fatigue Lifetime Distribution Estimation of Series Mechanical Systems under Random Load considering Strength Degradation Path Dependence

“…However, strength degradation path dependence (SDPD) is neglected when using this method, which could cause large calculation error as is described in the authors' former research [21].…”

“…It is difficult to provide an explicit expression of the time-dependent system structure function for system reliability computation. To address the problems above and take the load process and the strength degradation process as the input of proposed models, the lifetime distribution models of series mechanical systems are established based on the dynamic reliability models developed in the authors' previous research [21]. For a series mechanical system with components, the dynamic reliability can be calculated by…”

“…and are material parameters that describe the strength degradation process and can be referred to in [21].…”

“…The practical examples of series mechanical systems and parallel systems can be referred to in [21]. In this section, for illustrative convenience, it is assumed that the components are identical in the series system shown in Figure 12.…”

“…In this section, for illustrative convenience, it is assumed that the components are identical in the series system shown in Figure 12. The statistical parameters of load and material parameters in [21] are adopted for the components in the two systems, which are listed in Table 1. To validate the lifetime distribution models, MCSs are performed with the flow chart shown in Figure 7.…”