Study On Thermal Mechanical Fatigue Characteristics Of Cast Steel Brake Disc For High Speed Train

The reliability of the service of the brake disc is one of the main factors affecting the safety of the train.Judging from the service situation of high-speed trains at home and abroad,the failure mode of brake discs is mainly crack damage caused by thermal engine fatigue.Therefore,the influence of the temperature field and stress field distribution of the brake disc during braking and the mechanical load on the fatigue of the brake disc thermal engine is studied,to prevent the occurrence of thermal cracks,to develop a brake disc with good fatigue resistance,and to improve maintenance the process provides important theoretical reference and engineering practice value.This paper takes the brake disc of a high-speed train as the research object,and uses the finite element software ANSYS Workbench to systematically study and analyze the temperature field and stress field of the brake disc during the emergency braking of the high-speed train at 200 km / h.Perform thermal engine fatigue simulation analysis of the brake disc.The main work of this paper includes:(1)Consider the influence of parameters such as basic resistance and slewing mass on the braking of the EMU,and determine the parameters such as brake deceleration,braking time and braking distance according to the EMU braking specifications.The establishment of the heat flux density model provides more accurate numerical conditions.(2)According to the structural characteristics of high-speed train brake discs,establish a simplified three-dimensional finite element model of the brake disc,use the energy folding algorithm to determine the change of heat flux density on the friction surface of the brake disc,establish a convective heat transfer model that changes with time,and calculate and analyze the system The distribution of the temperature field during the emergency braking of the moving disk can obtain the temperature rise change and temperature diffusion law of each area of the brake disk during the braking process.(3)Using the sequential coupling method,combined with the mechanical load in the braking process,the stress field distribution of the brake disc during the emergency braking process is analyzed to obtain the relevant distribution law of the high stress region during the braking process.(4)According to the analysis data of the temperature field and stress field of the brake disc,the random load spectrum under emergency braking conditions is established,and the thermomechanical coupled fatigue analysis of the brake disc is performed.Through the comparison of stress biaxial indicator diagram and stress field analysis,the location of the fatigue vulnerable area of the disc surface was determined,and the service life of the brake disc was studied and predicted.The thesis analyzes the thermomechanical fatigue life characteristics of a certain type of high-speed train brake disc temperature field and stress field changes,which can provide a reference for brake disc structure design and material selection,and brake disc overhaul process.