Numerical simulation of the effects of elastic anisotropy and grain size upon the machining of AA2024

J Braz. Soc. Mech. Sci. Eng.

Al‐Zahrani

et al. 2019

This research work deals with the numerical modeling and analysis of macro-to microscaled milling of a strain rate-sensitive alloy AA2024T351. The milling computations of a semicircular slot are performed in Abaqus/Explicit by employing the Johnson-Cook thermo-elasto viscoplastic material damage model. The Coulomb friction model is applied at the contact interfaces of work piece and cutting tool. Due to the simultaneous effect of cutting feed and angular speed (ω r), the geometry of uncut chip is modeled with variable section thickness to adapt the trochoidal path. The configuration of the uncut chip undertakes the macro-to micromilling effect. This research effort uniquely explains a comprehensive modeling and milling computations at macro-to microscales to identify the imperative milling characteristics. The presented formulation in form of the modified Johnson-Cook constitutive equation explains the size effect during micromilling. A parametric sensitivity analysis is performed with four different cutting speeds (500, 600, 700, and 800 m/min) and two contact friction coefficients (0.2 and 0.3) while keeping the feed rate constant (0.2 mm/teeth). It was observed that cutting speed and contract friction coefficient play a pivotal role in cutting reaction force and chip-tool interface temperature. A temperature in the range of 141-167 °C is predicted with different cutting speeds. The percentage deviations of the simulated cutting forces from the published experimental results are found promising. The estimated deviation may be because of compromising some imperative factors in numerical model, such as cutter vibrations, tool wear effect, tool run-out, and limitations, to develop an exact trochoidal trajectory.

Section: Analysis Of Equivalent Plastic Strainmentioning

confidence: 99%

Numerical modeling and simulation of macro- to microscale chip considering size effect for optimum milling characteristics of AA2024T351

Saleem

J Braz. Soc. Mech. Sci. Eng.

Al‐Zahrani

et al. 2019

“…Plain strain hypothesis has been adopted here to perform 2D orthogonal machining simulation. Similar approach has also been used previously in published literature [11][12][13]. Plain strain continuum elements, CPE4RT, are used to mesh tool and workpiece.…”

Section: Machining Model Geometry Materials Behavior and Hypothesismentioning

confidence: 99%

Numerical Modeling the Effects of Chamfer and Hone Cutting Edge Geometries on Burr Formation

Asad

Djavanroodi

Wseas Transactions on Applied and Theoretical Mechanics

et al. 2020

Self Cite

A finite element based numerical model to simulate orthogonal machining process and associated burr formation process has been developed in the presented work. To incorporate simultaneous effects of mechanical and thermal loadings in high speed machining processes, Johnson and Cook`s thermo-visco-plastic flow stress model has been adopted in the conceived numerical model. A coupled damage-fracture energy approach has been used to observe damage evolution in workpiece and to serve as chip separation criterion. Simulation results concerning chip morphology, nodal temperatures, cutting forces and end (exit) burr have been recorded. Model has been validated by comparing chip morphology and cutting force results with experimental findings in the published literature. Effects of cutting edge geometries [Hone and Chamfer (T-land)] on burr formation have been investigated thoroughly and discussed in length. To propose optimum tool edge geometries for reduced burr formation in machining of an aerospace grade aluminum alloy AA2024, numerical analyses considering multiple combinations of cutting speed (two variations), feed (two variations) and tool edge geometries [Hone edge (two variations), Chamfer edge (four variations)] have been performed. For chamfer cutting edge, the “chamfer length” has been identified as the most influential macro geometrical parameter in enhancing the burr formation. Conversely, “chamfer angle” variation has been found least effecting the burr generation phenomenon.

“…Hillerborg et al [29] proposed that the fracture energy G f , required to open a unit area of crack as material property. The approach was proposed for concrete materials, but also provides promising results for ductile materials [28,30] because according to Hillerborg et al [29], the proposal crack is assumed to propagate when the stress at the crack tip reaches the tensile strength of the material. The equivalent plastic displacement at failure is calculated by Equation (5).…”

Section: Constitutive Model and Chip Separationmentioning

confidence: 99%

Finite Element Analysis and Statistical Optimization of End-Burr in Turning AA2024

Asad

Saleem

et al. 2019

Metals

Self Cite

This contribution presents three-dimensional turning operation simulations exploiting the capabilities of finite element (FE) based software Abaqus/Explicit. Coupled temperature-displacement simulations for orthogonal cutting on an aerospace grade aluminum alloy AA2024-T351 with the conceived numerical model have been performed. Numerically computed results of cutting forces have been substantiated with the experimental data. Research work aims to contribute in comprehension of the end-burr formation process in orthogonal cutting. Multi-physical phenomena like crack propagation, evolution of shear zones (positive and negative), pivot-point appearance, thermal softening, etc., effecting burr formation for varying cutting parameters have been highlighted. Additionally, quantitative predictions of end burr lengths with foot type chip formation on the exit edge of the machined workpiece for various cutting parameters including cutting speed, feed rate, and tool rake angles have been made. Onwards, to investigate the influence of each cutting parameter on burr lengths and to find optimum values of cutting parameters statistical analyses using Taguchi’s design of experiment (DOE) technique and response surface methodology (RSM) have been performed. Investigations show that feed has a major impact, while cutting speed has the least impact in burr formation. Furthermore, it has been found that the early appearance of the pivot-point on the exit edge of the workpiece surface results in larger end-burr lengths. Results of statistical analyses have been successfully correlated with experimental findings in published literature.