Effect of rake angle on Johnson-Cook material constants and their impact on cutting process parameters of Al2024-T3 alloy machining simulation

Abstract

Finite element modeling (FEM) of machining has recently become the most attractive computational tool to predict and optimize metal cutting processes. High-speed computers and advanced finite element code have offered the possibility of simulating complex machining processes such as turning, milling, and drilling. The use of an accurate constitutive law is very important in any metal cutting simulation. It is desirable that a constitutive law could completely characterize the thermovisco-plastic behavior of the machined materials at high strain rate. The most commonly used law is that of Johnson and Cook (JC) which combines the effect of strains, strain rates, and temperatures. Unfortunately, the different coefficients provided in the literature for a given material are not reliable since they affect significantly the predicted results (cutting forces, temperatures, residual stresses, etc.). In the present work, five different sets of JC are determined based on orthogonal machining tests. These five sets are then used in finite element modeling to simulate the machining behavior of Al2024-T3 alloy. The effects of these five different sets of JC constants on the numerically predicted cutting forces, chip morphology, and tool-chip contact length are the subject of a comparative investigation. It is concluded that these predicted cutting parameters are sensitive to the material constants.

Numerical analysis of constitutive coefficients effects on FE simulation of the 2D orthogonal cutting process: application to the Ti6Al4V

“…This latter generally involves coupled thermomechanical conditions added to the high nonlinearity caused by the interesting levels of strain, strain rate, and temperature undergone by the machined material. Therefore, the total understanding of the cutting process is still until now a great challenge that cannot be yet solved analytically or experimentally [1]. Interaction between different aspects like strain hardening, viscosity, thermal softening, hardening softening, loading history, and material microstructure changes that take place in extremely thin zone during a very short time period, as well as availability of many new and powerful software, are the origins of the wide use of finite element modeling (FEM) in these last decades.…”

“…These involved inverse identification methods appear more interesting and reliable than the former one due to the fact that they allow reaching a better correlation with less cost. However, it is of major importance to note that inverse methods generally cause the time increase with the number of the identified parameters added to problems related to solution diversity resulting thus on a great distinction in terms of chip morphology, temperature distribution, and shear angle [1].…”

Frictional behaviour of AA7075-O aluminium alloy in high speed tests

“…Among the models developed for describing the flow curve at high strain rate, the Johnson-Cook model is one of the most used and cited in literature [12,13,[33][34][35][36]. In the present work, the model capability to accurately predict the plastic flow behaviour of AA7075-O has been improved by modifying the static part of the Johnson-Cook equation according to the Voce model [37].…”

“…The Split Hopkinson Pressure Bar (SHPB), based on the one-dimensional propagation of elastic pressure waves in long bars, is the most widely used experimental apparatus to characterise the flow behaviour under the dynamic loading condition, in the range of strain rates varying from 10 2 to 10 4 s −1 [7][8][9][10][11][12][13]. This method was initially developed for carrying out compression tests [8], but later extended to tensile [9,14] and torsion [15] tests.…”

Establish Using FEM Method of Constitutive Model for Chip Formation in the Cutting Process of Gray Cast Iron

“…Because the Johnson-Cook [JC] constitutive model [27] correlates the effect of temperature, stress, and strain rate on material properties, this model is widely employed in metal cutting simulation processes [28][29][30]. Daoud [28] The Johnson-Cook constitutive model can be easily established from the experimental data achieved by the split Hopkinson press bar (SHPB) experiments with the different strain rate and temperature [31][32][33][34][35][36][37]. Wang et al [31] used the SHPB test to investigate the dynamic mechanical behavior of alloy Inconel 718 under high temperature and strain rate in practical cutting process.…”