Study On The Dynamic Destroy And Constitutive Relation Of Materials Taking Account Of Damage Evolution For High Speed Cutting

The adiabatic shear, which may produce serrated chip, usually occurs for a largenumber of materials in high speed machining. The appearance of adiabatic shear in highspeed machining may lead to the high frequency libration of cutting force, the increaseof tool wear and the reduce of finished surface quality. The phenomena of adiabaticshear in the process of the high speed machining were the special characteristic that thematerial occurs for dynamic damage. The research on phenomena of adiabatic shear ishelpful to appreciate the dynamic damage of processed material entirely by us. Thematerial can more or less occur for the localizing adiabatic shear in the high speedmachining. The localizing adiabatic shear is actually a kind of the strain hardening, thestrain hardening rate and the coupling effect to softening, and the large strain of, thehigh strain rate of, and the environment focused on heat of the primary shear zone, arejust in favor of the occurrence of adiabatic shear bands in the high speed machining.Broadly, any material can occur for the possibility of the localizing adiabatic shear inthe process of machining if only the speed of machining is sufficiently high, andequilibrium of strain hardening and heat softening to material can meet.Now there is no a good theory to explain the damage of adiabatic shear bands.Adiabatic shear damage and fracture were studied during high speed cutting andconstitutive relation taking account of damage was presented by theoretical model andexperimental study in this paper. It is shown that adiabatic shear bands occurred easilyin alloy steel and it is difficult to occur in carbon steel. A new damage evolutionequation that is dependent on strain, strain rate and is suitable for the description ofvoids damage evolution in adiabatic shear band. The corresponding rate-dependentconstitutive relation taking account of damage evolution and temperature are proposed.The predicted results are in good agreement with the experiment datum.