Reliability modeling for multi-component systems subject to multiple dependent competing failure processes with shifting hard failure threshold

For complex multi-unit systems whose sub-unit suffering multiple dependent competing failure processes (MDCFP) with shifting hard failure threshold, new multiple-component system models were developed in this paper. The previous studies about reliability analysis have focused on a single unit or simple system with s-independent failure processes and failure times. The new models are different from previous studies by extending unit-level degradation model to the system level. In this paper, each component in the system can be invalid owing to a hard failure process or a soft failure process. These failure processes mentioned-above are not only competing but also dependent and whichever happens first, the component fails. Moreover, the hard failure threshold can change due to the increment of the total degradation. Then, the reliability models for series, parallel, series-parallel system were derived respectively. Finally, numerical examples about Micro-electro-mechanical System (MEMS) are illustrated to verify the developed models and the results are effective. These models could be applied in MEMS or used in many other similar systems.