Numerical Simulation Of High Speed And Ultra-high Speed Machining Of Metal Using The Material Point Method

Manufacturing is the pillar industry for national economy,machining is one of the most basic method in the mechanical manufacturing.With the rapid development of modern manufacturing technology,all kinds of mechanical products need higher quality than before.So how to improve the efficiency and cutting quality of machining,and how to reduce cost of machining have always been the hot topics that people pay attention to.High-speed cutting technology has been developed rapidly and used in practical application in the 1980 s.As an important technology in the advanced manufacturing field,high-speed cutting technology has the advantages of good processing quality,less processing time and low processing cost etc.High-speed cutting technology is widely used in aviation,spaceflight,automobile,ship and mold manufacturing industry and it has extremely important significance in the national economy,social development and national defense construction etc.However,the mechanism analysis of high speed cutting process includes the elastic-plastic mechanics,fracture mechanics,heat transfer,thermodynamics,tribology,materials science,and mechanical dynamics etc.since the cutting process involves nonlinear subjects,so it is difficult to do very accurate theoretical analysis in the high speed cutting process.In recent years,with the development of computer technology and application of numerical methods,the numerical methods become a favorable tool for the numerical simulation of high speed machining.And high speed cutting process is always simulated with finite element method(FEM)by now.However,in numerical simulation of high speed cutting process,severe mesh distortion is usually encountered with conventional Lagrangian finite element method.The mesh distortion could reduce the accuracy,decrease the time step and even increase the probability of negative volume.This case greatly increases the computational burden,as well as makes the simulative results distortion.In order to overcome the weakness of mesh distortion with FEM in the numerical simulative process,many famous computational mechanics scholars present the meshless methods in recent years,which has no mesh distortion in the numerical simulative process.As thetypical meshless methods,smoothed particle hydrodynamics method(SPH)and material point method(MPM)have been widely used in many engineering fields.MPM has the advantages of Eulerian and Lagrangian Methods and is suitable to simulate the solid mechanics problems,especially for the high strain rate,high speed,large deformation,explosion,failure and fracture numerical simulations etc.It has been also succefully applied to the simulation of high speed cutting process.In this paper,Ti6A14 V titanium alloy workpiece material is used to simulate the high speed cutting process.During the transition between the continuous chip stage and the serrated chip stage,the simulations are carried out on the basis of material point contact method,and the development algorithm contains multiple factors including the heat transfer and phase change code.Using three modified Johnson-Cook thermal viscoplastic constitutive models,the high speed cutting process is simulated under the conditions of high strain rate,high speed,large deformation,high temperature difference,friction and complex phase change process.During the transition between the serrated chip and discontinuous chips,based on the MPM and modified Johnson-Cook thermal viscoplastic constitutive model,the fracture and damage failure algorithm is introduced into the simulation process.The observation and comparison of temperature,morphology,stress,damage and fracture etc.are carried out between the numerical and experimental results,and the results of the simulations and experiment are basic coincidence.