System-level damage-threshold interference model for system reliability evaluation

A system-level damage and threshold interference (SLDTI) model considering correlation information within a system is proposed based on probabilistic analysis framework in this paper. Based on the cumulative damage theory, the SLDTI model takes damage and threshold as two random variables to quantitatively characterize the uncertainty of external load and material properties, respectively. Compared with the traditional from-part-to-system reliability model, the SLDTI model is modeled directly from the system level so that the effect of statistical dependence between the failures of different parts within the system can be embodied inherently. An engineering case study of steam turbine rotor is given to illustrate the process of applying SLDTI model to system reliability assessment. Meanwhile, the surrogate model technology is applied to achieve the acquisition of the probability distribution of the damage of the reference part (RP) and the mapping of the failure correlation between the dangerous parts (DPs) in the system. Furthermore, the effect of uncertainty in damage and threshold on system reliability is quantitatively analyzed. The results indicate that the proposed model is more reasonable than traditional models, particularly when the system is subjected to a volatile service environment, which provides insights for operational maintenance and reliability optimization.