Research On Failure Mechanism And Reliability Evaluation Of Aviation Hydraulic Rotary Joint Components

The safety and reliability of aircraft is the primary guarantee for the normally working service of aircraft.The rapid development of China’s aviation industry has put forward higher and higher requirements for aircraft reliability.Component reliability is the basic component of system reliability.Research on failure mechanism,reliability assessment and life prediction of aviation hydraulic components can provide guidance for aircraft preventive maintenance,component performance upgrade,and spare parts management,and has important practical significance.The aviation hydraulic rotary joints are taken as the research object,the failure mechanism,reliability evaluation and life prediction methods of aviation hydraulic rotary joint are studied from the aspects of physical test of failure mechanism,finite element analysis of failure mechanism,structural reliability analysis,reliability evaluation method based on wear degradation process,friction and wear test of components,etc.It provides theoretical support for reliability evaluation and life prediction of hydraulic aviation rotary joints.The main research contents of this paper are as follows:(1)According to the actual working conditions of aviation hydraulic rotary joints,the ground reliability test platform is built to carry out the failure physical test of aviation hydraulic rotary joints.The main failure form and failure mechanism of aviation hydraulic rotary joint components are investigated by the surface topography detection method,and the variation rule of characteristic size during the working process of aviation hydraulic rotary joint components is obtained by the size detection method.The reliability evaluation method of aviation hydraulic rotary joints without failure data is established to realize the reliability evaluation under different working conditions.(2)The finite element method is used to calculate the stress and sealing characteristics of the seal components of the aviation hydraulic rotary joints under typical working conditions.The influence of different key structural parameters and working conditions on the stress and sealing characteristics of the seal components is studied.The influence of fit clearance,overlap size,working pressure and temperature on stress distribution,maximum internal stress,and contact stress of the retaining ring and O-ring are obtained.The effects of wear,bite,and material aging on the stress and sealing characteristics of the seal components are investigated.So the performance evolution characteristics of the rotary joint seal components under complex physical and chemical stresses are further revealed.(3)The reliability calculation method of aviation hydraulic rotary joints is established.The maximum stress value of seal components of aviation hydraulic rotary joints is predicted by the multi-agent model.The influence of material strength,working pressure,working temperature,overlap size and fit clearance on its reliability and local sensitivity is investigated.The reliability calculation method of aviation hydraulic rotary joints for the service process is constructed,and the real load spectrum is integrated into the structural reliability calculation process.(4)A reliability evaluation and life prediction method based on the gamma distribution of multiple random effects is constructed,and the prior distribution construction method is explored.Then the reliability evaluation and life prediction of the component wear of aviation hydraulic rotary joints are carried out based on the model.A fusion method of mathematical model and test for reliability evaluation of aviation hydraulic rotary joints is proposed.The method combines degradation process with failure model to improve the accuracy of reliability evaluation.(5)The friction and wear test device of aviation hydraulic rotary joint seal components is built,and its friction and wear characteristics under different working pressure and different motion parameters are studied.The effects of different working pressures and different motion parameters on the friction torque characteristics,power characteristics and wear characteristics of sealing components are analyzed.The time domain characteristics of friction torque time series under long working time are analyzed by principal component analysis method.With the use of scanning electron microscope,the test results of seal components are observed,and the wear change process of seal components is further clarified.In this paper,the failure mechanism of aviation hydraulic rotary joint is revealed,and the reliability evaluation method and life prediction method based on different failure behavior are proposed.The research results of this paper have theoretical significance for enriching the reliability evaluation and life prediction methods of aviation hydraulic rotary joints,and also have certain reference significance for the reliability evaluation of aviation components in China.