| Reciprocating seal is a key basic component of aero-hydraulic actuator,which is widely distributed in the elevator,rudder,landing gear system and other parts of the aircraft.Its quality directly affects the performance and safety of aerospace vehicles.Due to the development of aviation hydraulic system towards high pressure and high speed and frequent friction between reciprocating seals and pairs,the wear of seals is aggravated and the service life of reciprocating seals for actuators is greatly reduced.Therefore,it is of great significance to study the sealing mechanism and performance of reciprocating seal for actuator under high pressure for improving the life and reliability of actuator.In this paper,the O-ring of reciprocating seal is taken as the research object,and the static and dynamic sealing performance and structure optimization of reciprocating seal under high pressure are studied in combination with specific failure cases and engineering practice.Firstly,according to the actual installation mode of the reciprocating O-ring,the finite element models of axial propulsion and radial compression of the reciprocating O-ring are established by using the finite element analysis software.The comparative analysis shows that it is safer to use the finite element model of axial propulsion and radial compression to simulate the installation pre-compression of the O-ring under high pressure condition.Based on this,it is determined that the finite element model of axial advance pre-compression is adopted in this paper,and the installation structure parameters are optimized and analyzed.The rationality of the finite element analysis method is verified by the actual failure cases,and the influence of the structural parameters of the reciprocating sealing system on the operating conditions of O-ring is revealed.Considering the structural parameters,operating conditions and installation conditions,the structure of the reciprocating O-ring under the high and ultra-high pressure conditions is optimized by the orthogonal method.And compare the sealing performance before and after optimization.Then the finite element model of the optimized O-ring was established,and the effects of material,compression ratio and friction coefficient on the sealing performance under reciprocating condition were studied.The influence of the main operating parameters on the dynamic sealing performance parameters under high pressure and ultra-high pressure conditions was analyzed.It was found that the viscoelastic constitutive model was more effective.It can truly reflect the stress relaxation and creep characteristics of rubber sealing ring,and it is more safe and reasonable to use viscoelastic model to analyze.And the larger compression ratio and friction coefficient will cause the fluctuation amplitude of stress of reciprocating seal with the piston rod motion to increase,and the fluctuation of stress is more obvious under 35 MPa pressure.Finally,considering the working principle of aircraft actuator,the change of fatigue life of rubber seal ring under periodic alternating medium pressure and different reciprocating speed is studied.The results show that reciprocating speed has little effect on the fatigue life,and the fatigue life of the sealing ring is always at a lower level during the reciprocating stroke.However,when the reciprocating speed is too small,it is easy to cause the rubber sealing ring to crawl,and the fatigue life drops suddenly,and the greater the working pressure,the more obvious the phenomenon is.The cyclic pressure also causes the life fluctuation,and the fatigue life fluctuation amplitude of reciprocating O-rings under high pressure 21 MPa is larger than that under ultra-high pressure 35 MPa.In this paper,the sealing performance of high-pressure aeronautical reciprocating seals from installation to operation is systematically studied,and the fatigue life of reciprocating seals for actuators under working conditions is predicted and analyzed.Combined with actual failure cases and national standards,the installation structure is optimized,and the axial propulsion model is established to simulate the installation process.The influence of operating parameters and structural parameters on the static and dynamic sealing performance and fatigue life of reciprocating O-ring is studied in combination with the working principle of aero-actuator.It is found that the stress fluctuation of reciprocating O-ring under high pressure condition is large and has a great influence on the sealing life.However,due to the limitation of time and experimental conditions,there is no experimental verification,so the theoretical results can not be compared with the experimental results.Further study is needed to make a more accurate and comprehensive analysis of the performance of reciprocating dynamic seals in aviation high-pressure occasions. |
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