Deviation Analysis Of Small Scale Braking Model And 1:1 Braking Model

Small scale test as an important tool in the study of brake friction materials and has some advantages such as lower ratio of 1:1 brake test cost and short period,however,high-speed train brake pads form and arrangement of many kinds,resulting in small scale friction pair design difficulties and existing design the friction coefficient as the evaluation small scale model and a 1:1 model is similar to the extent of the only indicator,the lack of contrast to cause the brake disc thermal fatigue of temperature variation analysis.Therefore,it is of practical significance to study the structure design of the reduction of the brake pad,and to carry out the deviation analysis of the reduction ratio brake model and the 1:1 brake model.Based on the similarity principle,the key parameters of friction radius,number of friction surface,friction area and heat capacity of the brake disk are determined,and two kinds of scaling models are designed according to the braking friction pair of high speed train.Using ABAQUS finite element software to the existing TM-I small scale table test model design,small scale model and a 1:1 model were finite element modeling,comparative analysis of the temperature of the four kinds of models under different braking condition,radial temperature distribution and the maximum temperature,calculate the different small scale temperature coefficient than the brake model,discusses the small scale braking model and 1:1 brake model of similarity degree,and in TM-I small scale test bench to test the brake,effect of study of braking on the temperature of the brake disc.The results show that:(1)In accordance with the TM-I small scale test bench built brake model M1 of radial temperature distribution curve is in the shape of a parabola,1:1 brake model M4 radial temperature distribution curve showed a bimodal shape;different braking speeds of M1 is 2.25 than the M4 maximum temperature,namely the maximum temperature of the M4 is 2.25 times of M1,which suggests that the similarity of M1 and M4 is less.M1 and M4 highest temperature time of radial temperature curve and contact arc length distribution is consistent,contact arc length and the heat flux is proportional to determines the heat input size,contact arc length size is reflected in the high and low temperature,the friction between the two block arrangement difference lead to different contact arc length,this essentially the difference caused by the difference of Ml and M4 temperature distribution and size.(2)Based on the relationship between the temperature distribution and the contact arc length of M1 and M4,according to 1:1 model either the radius of the disc contact arc length for the proportion of the circumference of a circle,combined with small scale principle,designed for compression ratio brake structure is established based on the TM-I small scale test bench installation size scaled model M2 and complete according to small scale theoretical model of the M3.Through numerical simulation,it was found that consistency model M2 and M3 of radial temperature distribution and model M4 radial temperature distribution,different braking speeds model M2 and M4 maximum temperature than in the range of 1.02～1.19,M4 and M3 maximum temperature than in the range of 1.12～1.26,M2 maximum temperature than M3 more close to the M4 and brake disc structure,especially the thickness of about.This shows that the similarity model of M2 and M3 and M4 model is better,temperature variation can reflect the 1:1 brake model.(3)Under different braking pressure,the temperature distribution of the brake disc test results show that with the increase of the brake pressure,the maximum temperature of the braking process,at the low speed,brake pressure has little effect on the size and distribution of temperature,more uniform surface temperature,temperature along the radial curve was flat,while the at high speed,brake pressure,radial temperature gradient becomes larger,the radial temperature showed a parabolic curve shape,the disc radius 115～145mm range to form the high temperature zone.(4)Under different braking speeds,brake disc temperature distribution of test results show that with the increase of initial braking speed,braking process of maximum temperature elevation,disk high temperature region to friction radius are concentrated,increasing temperature gradient.