Reliability evaluation of systems with degradation and random shocks

This paper introduces a proposed model to evaluate the reliability of multi-component degradation systems suffering two kinds of competing failure causes: internal degradation process and damage from external random shocks. The internal degradation is expressed as a random process with respect to working time, and a geometric process is employed to describe cumulative damage caused by external random shocks. In our proposed model, the system is assumed to be failed when internal degradation or cumulative damage from random shocks exceed random life thresholds. The reliability expression is derived when the random life threshold and degradation process are considered to follow a Weibull distribution. A studied case of series-parallel system is presented to illustrate the proposed model, and a numerical algorithm is provided to simplify the calculating process based on normal approximation and assess the system reliability. Finally, Monte Carlo simulation method is employed to verify the model and algorithms.