Reliability analysis of composite insulators subject to multiple dependent competing failure processes with shock duration and shock damage self-recovery

Recent developments in composite insulators highlight the demand for reliability analysis, and similar to most engineering products, composite insulators experience multiple dependent competing failure processes. However, two distinct characteristics of the failure processes of composite insulators-sustained shock and self-recovery mechanism-have not received attention in previous studies, resulting in inaccurate assessments of their reliability. In view of these problems, a novel shock damage model is first proposed to accurately reflect the impact of harmful random shocks on the degradation processes of composite insulators, considering both the shock magnitude and the shock duration. Subsequently, a detailed self-recovery process considering both the recovery level and the recovery time is developed to reflect the self-recovery mechanism. Furthermore, an improved practical reliability model with an analytical expression is proposed for composite insulators subject to multiple dependent competing failure processes considering degradation processes, random shocks, and self-recovery processes. Finally, a numerical study of composite insulators is conducted to illustrate the implementation of the proposed model.