Study On Dynamic Characteristics And Performance Degradation Of Cushion Clamp In Aviation Pipeline

Aviation pipeline system is used for the transportation of hydraulic oil,fuel,lubricating oil and air.It is an important airborne system of aircraft.Aviation clamp is used to support and fix pipeline,and its mechanical characteristics have a great influence on the dynamic characteristics of pipeline system.Cushion clamp is one of the most common forms of support components of aircraft.It is mainly composed of metal hoop and rubber gasket.The hoop plays the role of support and fixation,and the rubber gasket plays the role of vibration reduction.Accurate acquisition of clamp stiffness and damping parameters is the premise of effectively predicting the dynamic characteristics of pipeline system.At present,there are few reports on the test and analysis of the mechanical characteristics of the aviation cushion clamp.Some documents propose to use the finite element static analysis method,the static loading method and the backstepping identification method of the vibration response test to obtain the support stiffness and damping parameters.The measurement accuracy of the mechanical parameters of the clamp needs to be further improved.With the development of airborne system to high speed and high pressure,the vibration problem of pipeline system is more prominent.It is urgent to study the dynamic characteristics of clamp.Therefore,taking the aviation pipeline cushion clamp as the research object,this paper studies the measurement method of mechanical stiffness and damping of the clamp by using the combination of numerical calculation,finite element simulation and experimental test,analyzes the vibration transmission characteristics of the clamp pipeline system,and reveals the degradation law of the dynamic performance of the clamp.The main research results are as follows:（1）An accurate measuring device for the mechanical stiffness parameters of the clamp is developed,and the measuring curves of the linear stiffness and torsional stiffness of the clamp are obtained.By introducing the stiffness parameters into the pipeline system dynamic model,the accuracy of stiffness measurement is verified by the comparison between numerical calculation and experiment.Furthermore,the measurement method of clamp damping is proposed.The damping parameters are identified by measuring the dynamic transmission rate of clamp,and the damping coefficient is introduced into the dynamic model of pipeline system.The effectiveness of clamp damping parameters is further verified by comparing the numerical calculation vibration response with the experimental results.（2）Aiming at the phenomenon that the influence of clamp parameters on pipeline vibration transmission is not clear,the dynamic transmission model of clamp pipeline under basic excitation is established,the displacement transmission rate of clamp pipeline system is deduced and calculated,the influence of clamp stiffness,damping and mass on vibration transmission relationship is further analyzed,and the influence law of clamp dynamic parameters on vibration transmission is revealed.（3）A test system for the degradation of the dynamic parameters of the clamp is built,and the degradation law of the dynamic performance of the clamp is revealed from three aspects: the dynamic transmission rate,the resonance response frequency and the vibration acceleration amplitude of the clamp.Further,through the finite element simulation analysis,it is determined that the fracture of the clamp is caused by the stress concentration,and the fatigue life of the clamp is simulated and analyzed.The test results verify the effectiveness of the clamp fatigue life analysis method.In this paper,the measurement method of the mechanical stiffness and damping parameters of the clamp is proposed,the dynamic transmission model of the clamp pipeline system is established,the influence law of the clamp dynamic parameters on the pipeline vibration transmission is revealed,the performance degradation test system of the clamp dynamic parameters is established,and the degradation law of the dynamic performance of the clamp is obtained.The research work of this paper provides a technical reference for the dynamic design and analysis of aviation clamp pipeline system.