Reliability Analysis of Load-Sharing Systems Subject to Dependent Degradation Processes and Random Shocks

Many systems often experience multiple failures resulting from simultaneous exposure to degradation processes and random shocks. For a load-sharing system, the dependencies among the degradation processes, random shocks and component failures potentially cause the system to fail more easily, which poses new challenging issues to evaluate the reliability. A novel reliability model for loadsharing systems subject to dependent degradation processes and random shocks is proposed. The new model extends previous models for simple parallel systems by considering the characteristics and specific dependencies of load-sharing systems. In a load-sharing system, the workload and shock load shared by each surviving component will increase after a component failure, leading to the higher degradation rate, the more serious sudden degradation damage caused by random shocks, and the greater probability of hard failure. In the model, the analytical expression is utilized to calculate the complex reliability. The complexity of this calculation is caused by the stochastic failure time of surviving components, the stochastic arriving time of shocks, and their interaction. A case of the load-sharing redundant micro-engines in micro-electromechanical system is presented to demonstrate the proposed model, and the result shows that the reliability of load-sharing system is lower than that of a simple parallel system.