Development And Simulation Of The Dynamic Seals Test System For Aircraft Cylinders

Hydraulic acuators are widely used in today’s aircrafts, such as to operate rudders and landing gears. Statics showed that nine out of ten removals of these acuators is due to external leakage. Since the reliability is mainly dependent on the reciprocating seals, it is obligate to develope a seal test rig for gound evaluation.Based on the COMAC919plan, a comprehensive test system developed for assessing reciprocating seals used in flight acuators is introduced in this thesis. Other than the currently-used3000psi aircraft hydraulic system, the rig is capable of simulating the operating condition of the aircraft hydraulic system at a rated4000psi pressure. Six chapters are included in this thesis.In chapter1, the background information of the project and related experimental studies and results on reciprocating seals are introduced, as well as the significance and main research subjects of this paper.In chapter2, the test methods and requirements of reciprocating seals in flight acuators are introduced. Two exsiting testing methods are compared and evaluated. The final test method of this rig is set and presented, including the seal assembly, force loading and impulse testing appoach as well as the ambient temperature control method.In chaper3, the overall hydraulic system scheme is proposed and detailed analysis and calculation of each module is given to fully illluminate the design and components selection. The force loading mechanism, contamination cannister installation and ambient temperature control system are designed and presented, as well as relevant calculation and evaluation.In chapter4, the simplified mathmatical model of I-type impulse loading is derived in detail and then analysised. The PI control method is discussed and the parameters for the controller is optimized. Finally a AMESim model is set up to evluate the performance of I-type impulse loading system.In chapter5, a lumped parameter model is derived to analysis the factors that affect the II-type impulse wave. Then a detailed AMESim model is set up to fully discusse and verify the relevant system parameters selection. In the end, a BP parallel controller is proposed and the simulation results show that compared to the traditional controller, the parallel controller could enhance the test efficiency. In chapter6, conclusions in this thesis are summarized and future research proposals are suggested.