Fatigue Analysis Study And Structural Optimization Of The TBM Split Cutterhead

Split cutterhead is one of the important parts of a tunnel boring machine(TBM).It’s performance directly affects the TBM’s lifetime and the quality of tunnel construction.In this paper,the author analyzed the fatigue characteristics of TBM split cutterhead and performed size-optimization on its weak part using Workbench.The main work of this paper includes:(1)Establishment the model of TMB split cutterhead.Build the 3-D model of the TBM split cutterhead according to the engineering drawings provided by CRCC.The cutter disc is properly simplified to meet the requirement of subsequent simulation analysis and structural optimization.Meantime,in order to improve the calculation precision,the virtual material modeling is used to simulate the mechanical properties of the joint surface between the cutter disks.(2)The force analysis of the TBM cutterhead.There were 51 disc cutters to be arranged on the cutter head.In order to simulate the actual force of the cutter accurately,this paper introduces the structure,grouping,rock breaking mechanism,motion characteristics and mechanical properties of cutterhead,and then analyzes the force of cutterhead.The Rostami prediction formula and the CSM prediction formula are used to calculate the load of the cutterhead,and the CSM prediction formula with higher prediction accuracy is selected after comparison.It lays the foundation for the following static mechanical analysis and fatigue analysis.(3)Fatigue analysis of TBM cutterhead.The finite element analysis method is used for static analysis of the cutter head.Fatigue analysis is worked out on the basis of static analysis results.Through the fatigue analysis module of Workbench,the life chart,damage cloud diagram,double axis indicating cloud diagram and safety factor cloud chart of cutter head are obtained.The primary factors affecting cutterhead’s fatigue life was analyzed.This will provided evidence for optimization of cutterhead design.(4)Optimization of TBM split cutterhead structure.Aiming at improving the life of cutterhead and reduce the maximum equivalent stress via the optimization module of Workbench,we carried out parameterized optimization on the weak parts of TBM cutterhead.After that,the minimal lifetime was increased by 88.96% which is 2985.7times more.And the maximal equivalent stress was decreased by 25.73% which is70.05 Mpa.By sensitivity analysis of relevant sizes,we determined the critical factors of the minimal lifetime and provided reference for design improvement.