Simulation And Analysis Of Spline Fretting Wear Of Helicopter Tail Transmission

In the tail transmission system of helicopters,excessive wear of spline pairs often leads to premature failure of other parts in the system,thus reducing the service life of the system.Therefore,the main causes of spline wear and the form and mechanism of spline wear are explored,the wear value of the tooth surface of the tail transmission spline is quantitatively calculated,and the anti-friction measures of the spline are proposed.It is very important to improve the spline wear and prolong the service life of helicopter tail transmission system.In this context,this paper combined the finite element simulation analysis with the friction and wear experiment of spline materials to explore the causes of helicopter tail spline wear based on fretting wear theory and Archard wear theory,and the method to quantitatively calculate the wear depth of spline tooth surface.Meanwhile,the influence of different factors on tail spline wear was explored.And based on the radial basis neural network model(RBF),the research work is carried out on the optimization of spline wear reduction structure parameters.The main research contents and conclusions of this paper are as follows:(1)Friction and wear experiment and data processing of spline materials.Friction and wear experiments were carried out on the spline materials.The experimental results show that the material wear amount after carburizing is smaller than that without carburizing,and the fretting wear coefficient of the material is also smaller than that without carburizing.The wear resistance of the material can be improved by surface carburizing.When the fretting wear coefficient of the same material is the smallest under grease 7019,its wear resistance will be improved.(2)Simulation verification of fretting wear and ideal spline model.The formula of fretting wear was modified based on Archard wear theory.It is verified that the method of calculating fretting wear by combining finite element and experiment is feasible.The ideal spline model was modeled and simulated.The results show that the stress distribution among different spline teeth is uniform and reasonable,which verifies the feasibility of using finite element method to simulate the stress of spline.(3)Simulation and analysis of the fretting characteristics of the tail transmission spline and research on the influencing factors.To end the system transient analysis,because the tail system bearing clearance,and spline clearance is longer than the other factors such as spline shaft vibration,at the same time,the internal and external spline tooth surfaces cause the relative sliding between mutual extrusion,the vibration and the relative sliding that generates spline tooth surface under the function of micro wear behavior.Under the vibration condition,the casing vibration will aggravate the wear of the spline tooth surface.It is found that with the increase of the applied load and the change of the lubrication condition(the increase of the friction coefficient),the wear of the spline tooth surface will be aggravated.(4)Optimization of tail-transmitted spline wear reduction structure parameters.Based on the radial basis neural network model,the nonlinear quadratic programming algorithm(NLPQL)was used to optimize the two structural parameters,namely,the internal spline backlash and the tooth drum modification,with the aim of minimizing the spline tooth surface wear,to find the best parameter combination.After optimization,the wear of both ends of the spline has been greatly improved.This optimization method can provide a reliable method for improving the wear of the spline pair tooth surface.