The Impact Of The Brake Disc Sizeon The Disk Temperature Field And Stress Field

During The high-speed train braking, brake disk has higher temperature and stress field, after many times braking, under cyclic stress, easily lead to fatigue failure of brake disc. As the main carrier of heat during the braking process, the brake disc size determines the heat capacity, has an important influence on the temperature field. Therefore, study on the influence of brake disc size to temperature field and stress field of the brake disk has great significance.This paper proposes the concept of size factor to measure the relations of size and the surface temperature field of brake disc, design scheme of the brake disc and brake pads with four size, using the finite element software ABAQUS and TM-I inertia scaling test platform,combining the numerical simulation and experimental analysis, analysis of the impact of the size of the brake disc the surface temperature field and stress field, the main conclusions are as follows:1.Put forward the concept of the size factor, the expression is:Llh R Rr×××=2020e, R, is the radius of a point of the arc length on the contact surface of brake pad and the brake disc,Ll is accounted for contact arc length in the circumference of the brake disc diameter ratio, h is the brake disc thickness, R0 is pad radius. Size factor is proportional to arc length of contact and friction radius, and inversely proportional to the brake disc heat capacity and friction circle perimeter, characterization of the frictional heat generation, the brake disc bearing capacity and the proportion of the loss on this friction radius, in order to reflect the temperature field of brake disk.According to the scheme composed of brake discs of different sizes, respectively, under the conditions of the initial velocity of 160km/h, 200km/h, 250km/h, brake pressure of 0.25 MPa, 0.375 MPa, 0.5MPa for finite element simulation. The results show that, in the different braking conditions, when the brake disc diameter is small, with the plate thickness increasing, the overall drop in temperature, and the temperature gradient becomes smaller, the brake disc heat stress decreased; when the brake disc thickness is constant, with the disc diameter increases, the temperature drop is not significant, but the temperature gradient is increased, resulting in thermal stress increases; when the friction radius of the brake disc with disk diameter increases, the maximum temperature decreased significantly and the temperature distribution be more uniformIn the different braking condition, the maximum value of size factor is proportional to the highest temperature and the maximum stress of the disk, and radial temperature and stress distribution is consistent with the trend of the size factor. When the friction radius of the brake disc as the size increases, the brake disc size factor decreased and the amplitude of variation is smaller, the highest temperature and the maximum stress value of the reduced; but when the brake disc and friction radius size unchanged, due to the increase of the temperature gradient, the maximum stress and the size factor has deviation.Be based on TM-I inertial scaling experiment were obtained the disk temperature field at different initial braking speeds and pressures, comparative analysis of the experimental and simulated the temperature and size of factor distribution. At the highest temperature moment in the process of braking under various conditions, the radial temperature distribution in the disk and the size factor in experiment and simulation showed a higher degree of agreement, which verifies the reliability of the numerical simulation results also show that the rationality of characterizing surface temperature field change by size factor.According to the 1:1 braking model was numerically simulated under different speed, found that the radial temperature distribution and change trend in the process of braking of 1:1 model is consistent with the disk size factor, at the maximum temperature of brake moment, size factor model can reflect the temperature distribution of the 1:1 brake disk.