Time-Dependent Reliability Sensitivity Analysis for Performance Degradation Mechanism

Reliability sensitivity analysis (SA) is a method to identify the relationship between the change in reliability and the change in the characteristics of uncertain variables. Very few methods can be applied for the reliability SA for long-term degeneracy mechanism, especially when the time-dependent limit state function regarding the interested performance is implicit. This paper proposes a new method to compute the reliability sensitivity measures. First, a surrogate model called time-dependent polynomial chaos expansion (PCE) is employed to approximate the uncertain output of the model and the extensive probabilistic collocation method (PCM) and moving least squares (MLS) method-based algorithm is proposed to compute the coefficients of the time-dependent PCE. Then, the explicit time-dependent limit state function can be obtained and the reliability sensitivity measures can be calculated straightforwardly. Finally, this approach is applied to an engineering case and the time-dependent reliability sensitivity measures are obtained for the long-term degeneracy mechanism model.