FEM simulation for orthogonal cutting of Titanium-alloy considering ductile fracture to Johnson-Cook model

Abstract

FEM simulation for the orthogonal cutting of Ti-6Al-4V alloy was investigated. Johnson-Cook's model was used for a flow stress equation of material. Rigid-plastic analysis was carried out using DEFORM-2D and AdvantEdge which were commercial software. For the constants in this model, the initial yield strength, the strain-hardening coefficient, the strain-rate sensitivity, the strain-hardening exponent and the thermal-softening exponent were used a reported value by Meyer-Kleponis. Failure accumulation in the Johnson-Cook model was considered by applying the Cockcroft & Latham law to the failure condition of materials. Some constants of material model and fracture limit value were estimated from the orthogonal cutting test. The friction between the chip and cutting tool was assumed the Coulomb friction μ=0.382. The friction coefficient that applied to simulation was calculated by the results of the cutting test. The validity of the calculation results were considered by comparing with the experimental results that were the cutting force, tool temperature and chip shape. When a ductile fracture condition was not considered (Df=0), the chip shape was calculated the flow type, the characteristic saw-tooth type in titanium alloy was not calculated. The chip shape was varied according to a limit value of the ductile fracture. The calculation result of the tool temperature was approximately accorded with an actual value. It was found that the cutting simulation of the titanium alloy was possible by the Johnson-Cook model that applied a ductile fracture condition as Df=0.1.

Keywords

• cutting
• fem
• titanium-alloy
• johnson-cook model
• ductile fracture condition