Copulas Arisen from Degradation-Based Time-to-Failure Models

There are a variety of degradation models in the literature, each with certain effect random variation around mean path on time-to-failure device being degraded. To assess dependence that exerts resulting time-to-failure, this paper presents copula functions for time-to-failure-based respect to two well-known models, namely, multiplicative model and additive model. The implied case have explicit forms. proved be symmetric deterministic failure, but copulas obtained when failure is affected uncertainly by asymmetric. Necessary sufficient conditions implicit given.