Friction And Wear Behaviors Research And Structural Optimization Design Of Disc Brake Pad

The disc brake of passenger car is a very important safety component,whose performance mainly depends on the contact condition of the interface between the sliding friction pair(disc and pad).The friction pair of disc brake will undergo quite complicated changes during braking process.The most obvious one is wear of the contact surface.However,the theoretical research about this field is still not mature.In order to reduce the wear and improve the uneven wear,this paper takes the disc brake pad as the main research object,focusing on the threedimensional finite element wear simulation,and introducing the double-piston brake pad.It proposes the optimization scheme pertinently,thus improving the friction and wear performance of the brake pad.Firstly,on the basis of sorting out a large number of domestic and foreign literatures,this paper analyses the shortcomings of the existing research work and determines the boundary conditions of the finite element model in the finite element software combined with friction heat generation theory and contact analysis theory.This paper proposes a finite element method for solving wear based on the subroutine UMESHMOTION in ABAQUS,which has certain guiding significance for in-depth analysis of friction and wear performance.Secondly,the wear model plays a decisive role in the wear simulation.In this paper,pinon-disc wear tests of resin-based materials are carried out,and the variation of friction coefficient and wear rate with temperature and load is revealed.It is concluded that friction coefficient and wear rate are sensitive to temperature and their variation curve is similar to inverted U-shape.The influence of load on friction coefficient is more complex,which is affected by load and contact area.The wear rate and load are almost proportional.Therefore,in order to reflect the dynamic characteristics of the wear model,the wear model of resinbased material is obtained by fitting the experimental data.On this basis,the wear model is embedded in the finite element software ABAQUS.The pin-disc finite element model is established,and boundary conditions are selected as the working conditions for simulation analysis.The dynamic change process of contact stress and wear is revealed in the analysis.The results show that the nodes at different locations have different contact stress distribution and different wear depth,which conform to Archard's wear law.At the same time,the error between the average wear depth and the theoretical wear depth is less than 7%,which verifies the accuracy of the numerical simulation method.The simulation results of the wear amount are in agreement with the experimental results..Considering the different brake concepts of single-piston brake pad and double-piston brake pad,and double-piston brake pad has good braking performance,the above-mentioned numerical simulation method is used to simulate the two kinds of brake pads under steadystate towing condition.The concept of Wear Centroid is proposed to evaluate the brake performance,focusing on the difference of actual area and wear amount between the disc pads.The simulation results show that the double-piston brake pad has larger contact area and reduces wear.Inhomogeneity.At the same time,the wear volume is relatively small,the wear life is longer,and the brake emission products respond less.Comprehensive evaluation shows that the braking performance of double piston brake pad is better and more conducive to the environment and human health.Finally,this paper uses Taguchi design method to analyze the sensitivity of the structural parameters of double-piston brake pad,clarifying the influence of each parameter on the output,and selects 40 groups of data samples to construct the approximate model of BP neural network.A cuckoo search algorithm based on Gauss perturbation is proposed to optimize the approximate model so as to avoid falling into local search and improve the convergence accuracy.Taking the actual contact area and wear as the optimization objective,the comprehensive objective method of multi-objective optimization method is used to optimize the parameters.The optimized results have been improved obviously,and the simulation results are remodeled according to the optimization scheme.The difference between the simulation results and the optimization results is very small,which proves the feasibility of the scheme.