A Study On Damage Law Of Adiabatic Shear Failure Of Speed Cutting Process

Numerous studies show that many of the workpiece material prone to adiabaticshear phenomenon in high-speed cutting process, accompanied by serrated chips as asymbol of adiabatic shear band, serrated chips will cause cutting force in the high-speedfluctuations, the impact of tool life, reduce the surface quality of the workpiece.For thepresent study serrated chip damage and destruction of properties of the law is still noreasonable explanation, the constitutive model of material does not accurately conveythe impact of mechanical properties of the material micro-damage caused.In this paper, use theoretical and experimental validation of methods to analyzedamage characteristic of serrated chip, and establish improved J-C constitutive model tostudy copper, copper alloy adiabatic shear sensitivity.The results show that bymicroscopic observation, microcracks generated and spread along adiabatic shear bands,the last formation long crack throughout the adiabatic shear band, which led to theformation of serrated chips; Combined with evolution model of micro-holes to analyzethe damage and failure characteristics of the chip, draw a conclusion that micro-holesgrow and come to mutual integration is a major factor in decreasing the mechanicalmacroscopic properties; By SHPB test, obtain dynamic mechanical data of copper,white copper B19, brass H62, bronze QAL9-4, and to analyze the dynamic mechanicalproperties;Using improved formula of the energy barrier to calculate G value of thematerials, and drawing adiabatic shear sensitivity of copper,white alloy B19, brass H62,bronze QAL9-4in turn enhanced;For the initiation and development characteristics ofmicro holes of adiabatic shear band, draw an explicit expression of damage variables,and derivation constitutive relations of considering the damage.