Research On ISD-based Landing Gear Taxiing Dynamics And Fatigue Damage Detection Of Key Components

Landing gear acts a significant role for the aircraft,such as gravity support,kinetic energy absorption,load reduce,and anyother ground handling actions.Failure of landing gear usually results in economic losses enormously,and even threaten to the passengers.Based on failure mechanism,the degradation or failure of the shock absorbers will cause the stress increase in the key components,leading to fatigue damage in the stress concentration portion in advance;And the fatigue damage of the key components will further reduce the damping performance of the shock absorber and even break it.Therefore,one of the effective solutions,is that to improve the performance of the shock absorber,meanwhile ensure that the health condition of the landing gear’s key components.However,the traditional shock absorber structures with Mass-Spring-Damper(MSD)can not to achive the goal.Developing the new suspension mechanism has become one of the inevitable choices to improve the performance of the landing gear absorber system.Based on the new damping mechanism,reseaching to the fatigue mechanism and monitoring method for the key components is significant to the landing gear.Therefore,the first scientific problem,are how to use the new shock absorption mechanism to improve the shock absorption performance;Secondly,how to detect the fatigue damage of the key components as soon as possible,so as to avoid the resulting accident.In order to solve the above problems,the main research works are as follows:(1)The network structure of the ISD mechanism.The basic characteristics,implementation structures,principles and nonlinear problems of the inerter are studied.The electro-mechanical similarity theory,network synthesis method and minimum implementation method based on ISD mechanism are studied.The topology and effectiveness of low complexity ISD mechanism are analyzed.The result show that the hydraulic inerter is more suitable for the landing gear absorber.The method for network design based on the combination of synthesis and topology can satisfy the requiement of the vibration structure design of the landing gear ISD mechanism.(2)Research on the method of taxiing dynamic modeling for the aircraft landing gear based on ISD structure.Calculate the equivalent static balance initial position for different ISD network structures.The 1-cos method and the random road surface spectral density are studied,and the design scheme of the test equipment for the taxiing is proposed.The dynamic modeling method during taxiing for single landing gear,and for full-aircraft based on ISD structure are studied.Based on the established model,carried out the simulation of the dynamic characteristics of the proposed ISD networks,which proves the improvement of the ISD structure on the performance of the aircraft.(3)Fatigue damage detection method for key components of landing gear.Research the nonlinear ultrasonic fatigue damage detection method for the key components of aircraft landing gear based on VAM experimentally.Analyzes the problem of the nonlinear source and modulation boundary condition in metal components.The research indicates that the VAM-based component fatigue damage detection method can fit the requirments of technical research such as the damping mechanism of the ISD structure landing gear and the health monitoring of key components.