The degradation model of servo valve with coupled failure mechanisms

The electrohydraulic servo valve requires steady and accurate performance in service time, while the structural degradations caused by wear and fluid contamination result in the performance degradation. The traditional methods of degradation modeling ignore coupling effect of structural degradations, so that some deviations exist in the system degradation model. In this paper, performance model of valve is created by simulation method using AMESim, while the structural degradation process of electro-hydraulic servo valve is built in mathematical method according to failure mechanism. Furthermore, the coupling effect of structural degradation is derived and added into structural degradation. Calculating the structural degradation and modifying corresponding structural parameter in performance model, the structural degradation with coupling effect is integrated into performance model. According to the simulation procedure, the performance degradation process is observed from the output of performance model, and two group measurements of rated flow from 200 hours experiment are collected. Comparing the simulation results with experimental measurements, we can find that system degradation model with coupled failure mechanisms is more accurate than the degradation model with independent failure mechanisms.