Fatigue Life Prediction Of The Subway Corbel Based On Fracture Mechanics

Fracture mechanics is a branch of solid mechanics,mainly studies the destruction of the component containing defects.The discipline began in the early 20th century,but has been rapidly development in the field of theory and experiments.This is mainly because of the significance of the safety of engineering materials and components.Corbel is the core load-bearing part of the subway body,and its safety performance plays a significant role in train safety running.Fatigue cracks often be found on corbels because of the complexity of the corbel structure and the running environment of urban subway lines.It is a serious hidden problem for the safety of the vehicle.We found a calculating method and process of corbel-residual life in view of the actual operating condition through analyzing subway's operation condition?using Hypermesh for strength analysis of the body?simulating stress intensity factor with ANSYS and finally predicting the residual life with fracture mechanics.This process provides reference data for economic repair and technical reference for research and development of car body.First,got the form of loads and constraints and the value of each load of simplified running condition,through the analysis of the running conditions of the subway line.Second,conducted the strength analysis of each working condition using HyperMesh software,got the stress-distributing condition of welds on corbel,determined the position and form of fictitious crack.Then,completed the test of crack propagation rate and the test of fracture toughness using the samples from the welds of the corbel,obtained the values of material constant of C?m from Paris formula,and the value of fracture toughness KQ.And then,by estimating the length of critical crack size ac,got the size and form of simplified model of the stress intensity factor,and got the function between stress intensity factor KI and crack length a by calculating stress intensity factor using ANSYS software.Finally,according to the actual operating condition of corbel,deduced the calculating formula of the residual life of corbel in the weld zone,and summarized a calculating process for residual life.