共因失效是由共同诱因引发的相关失效形式,普遍存在于各类系统,当前研究仅限于二态系统。该文针对存在共因失效的串并联不可修系统,探讨共因失效的发生与作用机理,基于载荷离散化方法和概率发生函数建立多状态系统可靠性定量评估模型,新模型可反映在失效共因下元件部分失效及其累积效应对系统各级性能的影响。研究表明,元件因失效共因而统计相关时,各元件状态趋同的概率增大,而取异值的概率减小,对系统可靠度分析产生影响。载荷离散化模型实现系统共因失效相关性的近似解耦,发生函数法能以统一的程序方式快捷处理概率组合问题。提出的模型为多状态系统共因失效及可靠性研究提供新途径。
Common cause failure, a kind of dependent failure mode in many systems, is initiated by some common causes. Study of common cause failures is confined to binary systems presently. In the light of non-repairable multi-state series-parallel systems with common cause failure, the mechanism of establishment and effect of common cause failure is represented, and a new reliability assesment model is put forward based on load discretization method and probability generating function approach. The new model can manifest the actions of partial failures in some components with a common failure cause and the corresponding accumulative effects on entire system performance. It is shown that the common cause can inevitably induce failure-dependence of all components in the common cause group. If some component-failures are dependent statistically due to a common cause, probability all components in the same state increments, which can effects the reliability assessment. The load discretization method realizes the approximate decoupling for failure-dependency, and the probability generating function approach is proved to be very convenient for different types of algebraic combination owing to relatively small computational resource costs. The model provides a new path for reliability study of multi-state systems with common cause failures.