Research Of Numerical Simulation Of Titanium Alloy In Cutting Process Based On SHPB Experiment And Simulation

Titanium alloy(Ti-6Al-4V) has become popular material in aviation, aerospace, chemical and mechanical industries owing to its excellent physical performances and mechanical properties, such as high specific strength, good resistance of corrosion and oxidation. However, the difficult machinability of titanium alloy greatly restricts its further application. Thus, the study on accurate constitutive model parameters of finite element simulation has important guiding effect on titanium alloy cutting, and this study has great meaning to improve the manufacturing technology in aerospace industry.This dissertation carried on the metallographic observation in order to fully understand the microstructure of titanium alloy(Ti-6Al-4V) material firstly. In order to obtain the stress- strain relationship of Ti-6Al-4V in wide range of temperature and strain rate, SHPB experiments were designed under these conditions whose strain rates were controlled from 2500s-1 to 10000s-1 and temperatures were from 20°C to 700°C. The effects of strain, strain rate and temperature on flow stress were analyzed according to the SHPB experimental results, and these experimental results using genetic algorithm were to optimize the J-C model parameters of Ti-6Al-4V.The finite element simulation of SHPB experiment for Ti-6Al-4V has been done using the J-C model parameters of the fitted results of SHPB experiment, and the simulated and experimental results of strain rate, flow stress and shear morphology were compared. The validation results show a good agreement that it indicates the J-C model parameters can accurately predict the material mechanical behavior in SHPB experiment.The finite element simulation of orthogonal cutting for Ti-6Al-4V has been done using the J-C model parameters of the fitted results of SHPB experiment. According to simulated results, the relationship between cutting speed and plastic strain rate was obtained to design the orthogonal cutting experiment for titanium alloy, and based on the experimental results, the effects of cutting speed on cutting force and chip morphology were analyzed. In addition, when the plastic strain stress of cutting zone is in the range of 10000s-1, the experimental and simulated results show the similar trend. This agreement indicates that the J-C model parameters can accurately predict cutting process when the plastic strain stress of cutting zone is in the range of 10000s-1, and it provides an effective method to develop the material constitutive model in the finite element simulation of cutting process for titanium alloy.