An Investigation On Some Issues Of Sealing Abrasive Wear And Life Prediction Of Certain Type Aircraft Actuator

Hydraulic actuator is an important component of aircraft hydraulic aviationcontrol system. The reliability of hydraulic actuator affects the sensibility andaccuracy of the flight attitude. Continuously working in high temperature and pressurein the long term, the function of the actuator relies on the sealing performance. Thefailure of the sealing can decrease the work efficiency of the hydraulic system, evenjeopardizes the security of the whole flight. While the actuator is working, the solidparticles inevitably float in the air, and the wear debris form in the sliding pairs. Thesewear debris will cause wear in the shifting pair between the sealing ring and the pistonrod, which can not be ignored. In this paper, the sealing property and life predictionare studied, which focus on the sliding pair between the sealing ring and the pistonrod of certain flight hydraulic actuator.Firstly, using the Hertz contact theory as the theoretical basis, the wear model forthe sealing structure is established, that is the transition from three-body abrasivewear to two-body abrasive wear, involving two wear stages and models. Based on theoblique-impact theory and Hertz damping contact theory, a three-body abrasive wearmodel is established. Then based on the plowing abrasive wear theory, a two-bodyabrasive wear model is established. Considering the contact surface quality, a t oilslick abrasive wear model is established.Secondly, considering the characteristics of the rubber material, a FEM model ofthe abrasive wear between the sealing ring and the piston rod is established usingANSYS. Then the two stages of the actuator sealing structure abrasive wear areanalyzed by FEM, to investigate the factors that influence the abrasive wear. TheFEM results turn out that the abrasive diameter have negative correlation and theimpacting speed positive correlation to the three-body abrasive wear. The criticalcondition of three-body abrasive wear is obtained, by which the three-body abrasive isjudged to happen. On the basis of the collusion above, contact stress, the mostimportant factor that help predicting the life of the actuator, is analyzed.Thirdly, the microcosmic abrasive contact stress is transformed to themacroscopical stress on the surface of the piston rod referring the G-W statistic model,and a statistic computing method for extra stress caused by abrasive wear is proposed.Using the combination wear computing method and considering the abrasion loss, alife prediction method is proposed.In the end, a whole virtual prototype of the hydraulic actuator is established withthe dynamics simulation software ADAMS, by which the working situation of the actuator under the extra contact stress caused by abrasive wear is simulated, so is themacroscopically influence caused by abrasive wear to the wear life. Then themicrocosmic grain contact theory above is confirmed.In this paper, there are three ways to study the sealing under the extra contactstress of abrasive wear, that is theoretical model, microcosmic stress and macroscopicstress. A judging criteria of sealing life prediction and abrasive wear of actuator isproposed. This paper provides a new factor for sealing improvement, a new field formeasuring the sealing, a new method for life prediction.