Performance degeneration analysis and reliability evaluation of servo valve

Generally, products especially aviation products must satisfy rigorous demand on the performance sensitivity caused by uncertainty disturbance. As long as performance indexes overstep the specified range, the temporal failure would happen. Otherwise, long time degeneration becomes increasingly obvious with usage and further intensifies performance sensitivity. So performance reliability gradually degrades. However, traditional reliability assessment methods are distinctly deficient when applied to evaluate performance reliability considering degeneration. Therefore, an improved method is proposed in this research. The definition and expression of performance reliability are presented first, and the theory of performance reliability evaluation considering degeneration is also introduced. To solve the simulation problem for the long time, a multi Monte Carlo algorithm is proposed. In the case of servo valve, according the procedure of the performance reliability evaluation method, initial uncertainty disturbance sub-models of design parameters& environment & noise, and degenerated uncertainty disturbance sub-models are both established. Then two kinds of submodels are respectively injected into the performance model to construct the integrated performance and reliability model considering uncertainty and degeneration. Finally time-dependent performance reliability is evaluated via the multi Monte Carlo method. Simulation results demonstrate that the method in this study is feasible.