Design And Analysis Of New Type Brake Disc For EMU Based On Finite Element Method

With the improvement of the speed of high-speed trains in our country,the safety of train operation has been paid more and more attention.Among them,the reliability of brake disc is one of the key factors affecting the safety of high-speed train operation,and also the last guarantee of train braking.The main failure mode of the brake disc is the thermal crack damage on the surface of the brake disc caused by the cyclic thermal load.Therefore,it is of great significance to study the heat dissipation performance of brake disc and the distribution of temperature field and stress field in braking process for the performance of brake disc and the subsequent service life prediction of brake disc.It also provides theoretical and engineering value for the design and use of brake discs.In this paper,the brake discs with two different heat sink structures are taken as simulation objects,and their heat dissipation performance is compared and analyzed by using FLUENT software.Then a new brake disc is designed,and its temperature field and stress field are simulated and analyzed by energy folding algorithm,and the influence of the thickness of the brake disc on its temperature field and stress field is discussed.The main work and conclusions are as follows:(1)Three-dimensional models of brake discs with two different forms of radiating ribs are established by using three-dimensional modeling software,and two models are meshed by using ICEM finite software.The mesh of brake disc is refined.The grid is imported into FLUENT software to calculate and analyze the distribution of velocity field and convection coefficient of two kinds of brake discs without heat sink.Among them,the air velocity of the column brake disc is higher than that of the strip brake disc,and the air velocity distribution in the duct of the column brake disc is more uniform.The maximum convective heat transfer coefficient of the cylinder brake disc is smaller than that of the strip brake disc,but the value of the convective heat transfer coefficient in the column ventilation duct is larger and more uniform.(2)According to the results of hydrodynamics calculation,a new type of cast steel brake disc with radiating rib is designed,and 1/10 of the brake disc is taken for simulation analysis.Using Hypermesh software to divide the grid of brake disc and refine the grid of brake disc has increased the calculation efficiency.The high precision hexahedral grid solid70 element is selected to ensure the calculation accuracy.The grid is imported into ANSYS to simulate and calculate its temperature field,and the stress field corresponding to the temperature field is calculated by indirect coupling method.When the initial speed of the new cast steel brake disc is 300 km/h,the high temperature of the disc surface for the next emergency brake is 333.343 C,and the corresponding maximum stress of the disc surface is210 MPa.The change trend of the temperature field and the stress field is basically the same.(3)Without changing the radiating rib of the brake disc,only the thickness of the brake disc is simulated and the mesh of the brake disc surface is re-divided,but the number of meshes is not changed.Importing ANSYS to carry out simulation calculation,every reductionof 0.5 mm is calculated once,and a total of nine groups of data are reduced by 4 mm.The simulation results show that the thickness of brake disc friction ring has little effect on its temperature field and stress field at the initial braking stage.When the thickness decreases by4 mm,the disc surface temperature increases by 8.24% and the thermal stress increases by12.85%.Therefore,the influence of the most stress on the thickness of the disc surface is higher than that of the temperature.In the braking process,the temperature and stress at the same point at the same time are taken as the curve of temperature and stress varying with thickness,and compared with the curve under the same conditions at the initial speed of 350km/h,it is found that the temperature and stress of the brake disc are basically linear with the thickness of the disc.