Research On Main Sealing Performance Of High Pressure Aircraft Actuator

The main seal of aircraft actuators belongs to typical reciprocating seals,which is a key component of the wings,doors,and many other parts of an aircraft,and it determines the safety of flights.With the improvement of the hydraulic pressure system,high pressure increases the seal deformation,and greatly reduces the life of the actuator main seal.Therefore,it is of great significance to carry out theoretical and experimental studies of actuator reciprocating seals under high pressure in order to improve the life and reliability of the actuators.Reciprocating seals were taken as the research object and the research method of theoretical analysis and experimental measurement is carried out in the study of reciprocating sealing performance under high pressure and surface modification methods in this paper.Based on finite element theory,the ABAQUS software is used to establish a pressure penetration method,which can search for the boundary point of the contact and separation automatically,and the finite element simulation analysis of full pressure condition of reciprocating sealing under(0MPa-35MPa)has been completed.The simulation process consists of interference installation,fluid pressure loading as well as the movement of instroke and outstroke.Sealing ring stress strain contours under the condition of different pressure has been acquired,and the areas of the maximum stress and strain under different pressures were analyzed.Moreover,we obtained the contact pressure distribution of the seal lip,which is the basis of the numerical calculation.A mixed lubrication model of reciprocating seal considering dynamic pressure effect and the effect of the contact between the asperities and the piston rod has been developed based on inverse lubrication theory(IHL).The model couples the analysis of solid mechanics of the sealing lip,fluid mechanics of oil film between seal and the piston rod,dynamic pressure effect caused by seal entrance convergent wedge,and contact mechanics between the asperities and the piston rod.For the reciprocating seals studied in this paper,the variations of reverse pumping rate,friction with pressure and speed are calculated by using numerical simulation.Inaddition,the mixed lubrication model is verified by the high pressure reciprocating seal bench test that is designed and built independently.The bench test can simulate aircraft actuator working condition ofhigh pressure(35MPa),and can measure the friction of instroke and outstroke of a single seal.It makes the simulation be correct and the results be convergent each other.Reverse pumping rate,friction force and the maximun of contact pressure in contact area was taken as the analysis target,parametric analysis was carried out for the reciprocating sealing section to obtain the optimal combination of the oil side angle and air side angle.At the same time,based on the standard ball plate experiment,the technique of interface modification of antifriction wear-resisting with MoS2 and DLC film coating on surface are explored.Furthermore,the DLC film has been coated on the metal piston rod,through long time bench experiment.It is confirmed that the DLC film coating on the surface of the piston rod can increase the life of lip seal ring effectively.