Prediction And Analysis Of Fatigue Life Of TBM Cutterhead Welded Structure

Full-face tunnel boring machine(TBM)is important large-scale mechanical equipment in engineering.The cutter head is an important part of TBM,and its service life directly affects the construction progress.The TBM cutter head is mainly assembled by welding,and it will encounter extremely complicated working conditions during the tunneling process.The welding area of the cutter head is prone to different degrees of fatigue damage,which will eventually cause a serious accident of fracture.Therefore,it is very important to study the structure of the damaged area of the cutter head and predict the service life.In this paper,the notch stress method is used to study the fatigue life of the welding area of the TBM cutter head.According to the actual tunneling conditions of the TBM cutterhead,the load spectrum of different types of hobs is established,and the transient finite element analysis is performed on the cutterhead to obtain the maximum stress area of the cutterhead.Due to the huge size of the cutter head,the virtual notch radius method is used to model and simulate the cutter head ribs by means of sub-models,and the stress distribution and size of the weld toe and weld root are studied in more detail.Based on the fatigue cumulative damage theory,the fatigue life of the cutterhead ribs is evaluated based on the n Code fatigue analysis software.Through the establishment of a five-frame flowchart of fatigue analysis,the parameters of the fatigue analysis software are set,and the fatigue damage distribution of the stiffener plate and the minimum number of cycles are obtained.And according to the TBM technical parameters,calculate the TBM cutter head’s tunneling distance life.Using the theoretical method of stress concentration factor,the virtual notch radius method is used for parametric modeling.Perform finite element analysis on butt joints and ribs,study the change process of various weld parameters of the model under different loads,and the influence on stress concentration,and summarize the change law of stress concentration coefficient,providing reference for improving the strength design of welded joints in accordance with.Using the theory of thermo-elasto-plasticity,the welding process is simulated by moving the heat source and the life and death unit,and the temperature field temperature change and the residual stress distribution of the stress field of the butt joint and the ribs are studied.Set up a variety of stress paths,and summarize the residual stress distribution curves in all directions.