Strength And Wear Analysis Of Spline In Aircraft Flap Transmission System

The flap of airplane is a movable device on the wing surface at the front and rear edges.Its main function is to increase the lift force of airplane in the process of take-off and landing,so the reliability of involute spline studied in this paper is directly related to the safety state of airplane.This involute spline has characteristics of small size,low torque and high speed,and damage caused by wear is the main failure mode in actual.The strength and wear performance of 20 CrMnTi spline are researched with the help of finite element transient simulation and material experiment.The main contents are as follows:Firstly,the three-dimensional FEA model of the spline is established and the correctness of the model is verified by comparison with the theory.Based on FEA model,Simulation result shows the phenomenon of unbalanced loading caused by the lack of coaxiality,which is one of the main reasons for the strength and wear problem of this spline in the actual working process.The axis angel of the inner and outer spline will cause the load at one end of the spline surface far greater than the other end,and the load will be sinusoidal distribution on different teeth.Simulation results prove that larger load can reduce the unbalanced loading phenomenon.Secondly,the involute spline undergoes both torque and axial force in actual working process,resulting in uneven stress on the tooth surface.The method of tooth surface modification is put forward to reduce the excessive stress on the surface.The relationship between the radius of the modification arc radius R and the modification amount s is derived.After accurately obtaining the spline after the tooth surface modification,the thesis has established three-dimensional FEA modification model,then the rationality of modification is verified by the simulation.Thirdly,the rotary wear experiment of 20 CrMnTi disc was carried out by the multifunction on-line wear tester.The relationship between the wear variables and the wear depth was quantitatively investigated.At the same time,the microstructure of wear groove was analyzed,so the wear resistance of the material was deeper understood.The test laid the foundation for numerical calculation of the spline wear depth in the next chapter.Finally,based on the classical Archard wear model,the numerical integral expression of the Archard model is derived.The wear coefficient of the material is obtained by comparison between simulation and experiment.Using the numerical integral function of MATLAB,the integral solution of the wear depth of the spline rotation for one cycle is solved.The measures to reduce the wear are discussed,which is spline modification before using.Proper shape modification makes the whole tooth surface wear speed to converge,so as to improve the service life of spline.