Simulation Analysis Of Defected Truck Brake Shoe

With the high-speed heavy-load railway plans, heavy haul railways wagon is more and more important in national transportation, then heavy haul railways wagon in the running safety problem has become more and more important. Brake system is an important part of railway safety plan in our country and one of the important conditions to assure the safety of train and reliable operation, thus puts forward more strict requirements on the braking system. High friction coefficient composition brake shoe is the best shoe now developed braking ability, has been widely used in the railway wagon in China, it is not only related to the heavy haul railways train operation safety and maintenance costs of vehicles also plays an important role.Nondestructive brake shoe brake is presented in this paper, on the basis of simulation analysis of the process of research with the temperature field and stress field in the process of defect brake shoe brake. Using finite element analysis software with surface crack, the internal cracks, bubbles in the surface of the brake shoe in the analysis of temperature field and stress field under different braking condition, compared with the limit of the brake shoe material parameters, to determine whether a shoe will damage in the process of braking.Paper main conclusions are as follows:(1) whether brake shoe with a surface crack, internal crack and surface bubbles, the values of stress concentration in the process of emergency braking or K1 of crack front than grew up in the ramp speed brake produced by stress concentration in the process of value or K1, therefore, in the process of emergency brake shoe are more likely to happen damage or crack extension. So should try to avoid in the process of vehicle emergency braking.(2) The length of surface tiny crack in both emergency braking and speed adjustment of brake shoe brake in the process of maximum temperature and maximum stress value is tiny impact, but the length of the tiny crack has influence to the stress intensity factor of the crack front, The larger crack, stress intensity factor will be greater, the more prone to crack. When checking the brake shoes, brake shoe should pay particular attention to the length of surface cracks.(3)Brake shoe inside tiny cracks have little impact on the performance of brake shoe, during braking the maximum temperature and the maximum stress will not appear on the internal crack and stress intensity factor of the crack front value is much less than the stress intensity factor of the brake shoe friction body limit, crack propagation phenomenon will not occur. To contain brake shoe can consider the appropriate application of the internal tiny crack.(4) Brake shoe of tiny bubbles while the values of stress concentration in the process of emergency brake will be greater than the maximum stress value in the process of nondestructive brake shoe brake, but because of the particularity of speed regulating brake, the diameter of bubble surface, the greater the value of stress concentration will be smaller, to later in the control of motor speed is less than the brake shoe brake process of maximum stress value.(5) With crack brake shoe during braking shoe than with stress concentration value of bubble in the stress when braking, so with the crack of brake shoe has great risk.