The Influence of Material Constitutive Constants on Numerical Simulation of Orthogonal Cutting of Titanium Alloy Ti6Al4V

2008 ◽  
Vol 375-376 ◽  
pp. 182-186 ◽  
Author(s):  
Jian Ling Chen ◽  
Jian Feng Li ◽  
Jie Sun ◽  
Zhong Qiu Wang ◽  
Zhi Ping Xu

Johnson-Cook (JC) constitutive model is extensively used in the simulation of metal machining. There are several different sets of JC material constants for titanium alloy Ti6Al4V fitted by split-Hopkinson bar (SHPB) tests. However, few researches have been done to study their sensitivity on the behavior of cutting. In this work, four different sets of material constants were performed in a 2D numerical model to simulate the cutting process of titanium alloy Ti6Al4V. The effects of the four sets of material constants on the predicted cutting forces, chip morphology and temperature were studied. It is shown that all the considered process outputs are very sensitive to material constitutive constants. Some quantitive comparisons with experimental results reported in the literature were also made.

Author(s):  
Yun Chen ◽  
Huaizhong Li ◽  
Jun Wang

Titanium and its alloys are difficult to machine due to their high chemical reactivity with tool materials and low thermal conductivity. Chip segmentation caused by the thermoplastic instability is always observed in titanium machining processes, which leads to varied cutting forces and chip thickness, etc. This paper presents an analytical modelling approach for cutting forces in near-orthogonal cutting of titanium alloy Ti6Al4V. The catastrophic shear instability in the primary shear plane is assumed as a semi-static process. An analytical approach is used to evaluate chip thicknesses and forces in the near-orthogonal cutting process. The shear flow stress of the material is modelled by using the Johnson–Cook constitutive material law where the strain hardening, strain rate sensitivity and thermal softening behaviours are coupled. The thermal equations with non-uniform heat partitions along the tool–chip interface are solved by a finite difference method. The model prediction is verified with experimental data, where a good agreement in terms of the average cutting forces and chip thickness is shown. A comparison of the predicted temperatures with published data obtained by using the finite element method is also presented.


Materials ◽  
2019 ◽  
Vol 12 (24) ◽  
pp. 4145
Author(s):  
Xiaohua Qian ◽  
Xiongying Duan

As a typical high specific strength and corrosion-resistant alloy, titanium alloy Ti6Al4V is widely used in the aviation, ocean, biomedical, sport, and other fields. The heat treatment method is often used to improve the material mechanical properties. To investigate the dynamic mechanical properties of titanium alloy Ti6Al4V after heat treatment, dynamic compressive experiments under high temperature and high strain rate were carried out using split Hopkinson press bar (SHPB) equipment. The stress–strain curves of Ti6Al4V alloy under different temperatures and strain rates were obtained through SHPB compressive tests. The Johnson–Cook (J–C) constitutive equation was used for expressing the stress–strain relationship of titanium alloy under large deformation. In addition, the material constants of the J–C model were fitted based on the experimental data. An orthogonal cutting simulation was performed to investigate the cutting of Ti6Al4V alloy under two different numerical calculation methods based on the established J–C model using the finite element method (FEM). The simulation results confirm that the adiabatic mode is more suitable to analyze the cutting of Ti6Al4V alloy.


2011 ◽  
Vol 117-119 ◽  
pp. 1788-1791
Author(s):  
Yue Feng Yuan ◽  
Wu Yi Chen

It is necessary for cutting simulation to determine the friction model at the tool-chip interface suitable for metal cutting process. Cutting force experiments in orthogonal turning titanium alloy TI6AL4V are carried out with cement carbide tool KW10. The Coulomb frictions at the tool-chip interface are calculated based on measured cutting force, and the friction model is regressed, where cutting speed and feed rate are presented.


2014 ◽  
Vol 800-801 ◽  
pp. 81-86
Author(s):  
Zhen Li ◽  
Er Liang Liu ◽  
Teng Da Wang ◽  
Jiao Li ◽  
Yong Chun Zheng

The various feed rate and cutting speed have an important influence on cutting force, tool wear and chip morphology in machining titanium alloy. Cutting experiments are carried out analyzing the titanium alloy Ti6Al4V under different cutting speed and feed rate, the cutting force values are obtained. The analysis results show that the dominant wear pattern is adhesion wear and chipping. And the tool wear also has an influence on chip morphology.


Author(s):  
Yun Chen ◽  
Huaizhong Li ◽  
Jun Wang

A cutting force model, based on a predictive model for orthogonal cutting, is developed for force predictions in end milling of titanium alloy Ti6Al4V. The model assumes a semi-stationary process for the serrated chip formation. The Johnson–Cook material model that couples strain hardening, strain rate sensitivity and thermal softening effects is applied to represent the material strength. A thermal model considering the tool thermal properties is integrated to account for the high temperature rise due to the low thermal conductivity of Ti6Al4V. To extend the predictive model to milling, the end mill is discretised into several axial slices, and an equivalent cutting edge is used to include the end cutting edge effect caused by the first axial slice. The model is assessed by comparing its prediction with the experimental results and a mechanistic model for verification. The results show that the proposed model outperforms the mechanistic model with higher accuracy in force prediction.


2011 ◽  
Vol 223 ◽  
pp. 162-171
Author(s):  
Yan Cheng Zhang ◽  
Domenico Umbrello ◽  
Tarek Mabrouki ◽  
Stefania Rizzuti ◽  
Daniel Nelias ◽  
...  

Nowadays, numerical simulation of cutting processes receives considerable interest among the scientific and industrial communities. For that, various numerical codes are used. Nevertheless, there is no uniform standard for the comparison of simulation model with these different software. So, it is often not easy to state if a given code is more pertinent than another. In this framework, the present work deals with various methodologies to simulate orthogonal cutting operation inside two commercial codes Abaqus and Deform. The aim of the present paper is to build a common benchmark model between the two pre-cited codes which can initiate other numerical cutting model comparisons. The study is focused on the typical aeronautical material - Ti-6Al-4V - Titanium alloy. In order to carry out a comparative study between the two codes, some similar conditions concerning geometrical models and cutting parameters were respected. A multi-physic comprehension related to chip formation, cutting forces and temperature evolutions, and surface integrity is presented. Moreover, the numerical results are compared with experimental ones.


2013 ◽  
Vol 365-366 ◽  
pp. 1235-1239 ◽  
Author(s):  
Jian Fu Zhang ◽  
Zhi Meng Chen ◽  
Ping Fa Feng ◽  
Wan Hong Xu

A comparative experimental study on the orthogonal cutting of titanium alloys by a polished tool, a tool containing a chip breaker groove, and a surface-textured tool was performed. The effects of different cutting tools on chip morphology, chip thickness, length and width of crack defects inside the chip, saw-teeth of the chip, and chip curl radius were analyzed during the cutting of a titanium alloy. Compared to chips formed by other tools, curled chip fragments formed by the surface-textured tool exhibited greater thickness and longer crack defect depths but smaller chip tooth pitches and curvature radii. The microstructural mechanisms involved in the interaction between the micro-texture surface cutting tool and the chips were analyzed by evaluating the cutting and texture parameters. The chip-breaking mechanism is that the micro-texture on the tool surface creates a sticky texture, leading to the micro-cutting and wrenching of chips, thereby increasing the magnitude of the tools work-hardening and chip-breaking effects.


2011 ◽  
Vol 325 ◽  
pp. 406-411 ◽  
Author(s):  
He Yong ◽  
Yu Jing Sun ◽  
Mao Jie Ge ◽  
Jian Feng Li ◽  
Jie Sun

Cooling/lubrication conditions have significant influences on surface integrity, chip morphology, tool life and eventually productive efficiency when machining titanium alloy Ti6Al4V. Milling experiment under different cooling/lubrication conditions, namely dry, wet, MQL and nitrogen gas jet were conducted. Cutting forces, surface roughness and chip morphology are obtained. It is shown that cooling/lubrication conditions influence cutting force greatly while its effect on surface roughness is not obvious. The chip surface contacted with rake face under nitrogen gas is smoother than that under dry, but there exists nitrogen adsorption of the chip at higher speed.


2016 ◽  
Vol 723 ◽  
pp. 171-176
Author(s):  
Ashwin Polishetty ◽  
Guy Littlefair ◽  
Sanjay Tumma

The research aim is to study and analyze the shear zone by application of merchant circle during machining of titanium alloy (Ti6Al4V). The thermo-mechanical reaction during machining plays an important role in defining machinability of titanium alloys. The scientific community is concerned about machining of titanium alloy due to problems occurring in the shear zone that affect tool life. Studying the cutting action contributes to understanding and addressing these problems effectively. For this purpose, an experimental setup, utilizing a high speed camera will be used to study the shear zone. The shear zone characteristics are studied by analyzing the images captured by a high speed camera placed near to the shear zone during machining. The experimental design consists of conducting a series of turning trials using combination of cutting parameters namely constant spindle speed (n) 770 rpm; feed rate (f) of 2 and 4 mm/rev; and depth of cut (d) of 1 and 2 mm. The length of cut (L) of 10 mm remains constant and no coolant is used for all trials. The images obtained from the camera are analyzed against the theory of orthogonal cutting using merchants circle.


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