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Gaobo Xiao - One of the best experts on this subject based on the ideXlab platform.
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a study of mechanics in brittle ductile Cutting Mode transition
Micromachines, 2018Co-Authors: Gaobo Xiao, Mingjun RenAbstract:This paper presents an investigation of the mechanism of the brittle–ductile Cutting Mode transition from the perspective of the mechanics. A mechanistic Model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile Mode deformation is to follow the elastic stage. It is revealed that, the distance of tool advancement required to induce the same level of compressive stress decreases with undeformed chip thickness, and thereby the tensile stress below and behind the tool decreases with undeformed chip thickness. As a result, the tensile stress becomes lower than the critical tensile stress for brittle fracture when the undeformed chip thickness becomes sufficiently small, enabling the brittle–ductile Cutting Mode transition. The finite element method is employed to verify the analysis of the mechanics on a typical brittle material 6H silicon carbide, and confirmed that the distance of the tool advancement required to induce the same level of compressive stress becomes smaller when the undeformed chip thickness decreases, and consequently smaller tensile stress is induced below and behind the tool. The critical undeformed chip thicknesses for brittle–ductile Cutting Mode transition are estimated according to the proposed mechanics, and are verified by plunge Cutting experiments in a few crystal directions. This study should contribute to better understanding of the mechanism of brittle–ductile Cutting Mode transition and the ultra-precision machining of brittle materials.
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A Study of Mechanics in Brittle–Ductile Cutting Mode Transition
MDPI AG, 2018Co-Authors: Gaobo Xiao, Mingjun RenAbstract:This paper presents an investigation of the mechanism of the brittle–ductile Cutting Mode transition from the perspective of the mechanics. A mechanistic Model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile Mode deformation is to follow the elastic stage. It is revealed that, the distance of tool advancement required to induce the same level of compressive stress decreases with undeformed chip thickness, and thereby the tensile stress below and behind the tool decreases with undeformed chip thickness. As a result, the tensile stress becomes lower than the critical tensile stress for brittle fracture when the undeformed chip thickness becomes sufficiently small, enabling the brittle–ductile Cutting Mode transition. The finite element method is employed to verify the analysis of the mechanics on a typical brittle material 6H silicon carbide, and confirmed that the distance of the tool advancement required to induce the same level of compressive stress becomes smaller when the undeformed chip thickness decreases, and consequently smaller tensile stress is induced below and behind the tool. The critical undeformed chip thicknesses for brittle–ductile Cutting Mode transition are estimated according to the proposed mechanics, and are verified by plunge Cutting experiments in a few crystal directions. This study should contribute to better understanding of the mechanism of brittle–ductile Cutting Mode transition and the ultra-precision machining of brittle materials
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molecular dynamics Modelling of brittle ductile Cutting Mode transition case study on silicon carbide
International Journal of Machine Tools & Manufacture, 2015Co-Authors: Gaobo Xiao, Guoqing ZhangAbstract:Abstract The mechanism of brittle–ductile Cutting Mode transition has received much attention over the past two decades. Due to the difficulties in directly observing the Cutting zone during the brittle–ductile Cutting Mode transition by experimental techniques, many molecular dynamics (MD) studies have been conducted to investigate the atomicscale details of the phenomena, e.g. phase transformation, stress distribution and crack initiation, mostly under nanoscale undeformed chip thicknesses. A research gap is that direct MD Modelling of the transition under practical undeformed chip thicknesses was not achieved in previous studies, due to the limitations in both computation capability and interaction potential. Important details of the transition under practical undeformed chip thicknesses thereby remain unclear, e.g. the location of crack formation and the stress distribution. In this study, parallel MD codes based on graphics processing units (GPU) are developed to enable large-scale MD simulations with multi-million atoms. In addition, an advanced interaction potential which reproduces brittle fracture much more accurately is adopted. As a result, the direct MD simulation of brittle–ductile Cutting Mode transition is realised for the first time under practical undeformed chip thicknesses. The MD-Modelled critical undeformed chip thickness is verified by a plunge Cutting experiment. The MD Modelling shows that tensile stress exists around the Cutting zone and increases with undeformed chip thickness, which finally induces brittle fractures. The location of crack formation and direction of propagation varies with undeformed chip thickness in the MD simulations, which agrees with the surface morphologies of the taper groove produced by the plunge Cutting experiment. This study contributes significantly to the understanding of the details involved in the brittle–ductile Cutting Mode transition.
Guoqing Zhang - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamics Modelling of brittle ductile Cutting Mode transition case study on silicon carbide
International Journal of Machine Tools & Manufacture, 2015Co-Authors: Gaobo Xiao, Guoqing ZhangAbstract:Abstract The mechanism of brittle–ductile Cutting Mode transition has received much attention over the past two decades. Due to the difficulties in directly observing the Cutting zone during the brittle–ductile Cutting Mode transition by experimental techniques, many molecular dynamics (MD) studies have been conducted to investigate the atomicscale details of the phenomena, e.g. phase transformation, stress distribution and crack initiation, mostly under nanoscale undeformed chip thicknesses. A research gap is that direct MD Modelling of the transition under practical undeformed chip thicknesses was not achieved in previous studies, due to the limitations in both computation capability and interaction potential. Important details of the transition under practical undeformed chip thicknesses thereby remain unclear, e.g. the location of crack formation and the stress distribution. In this study, parallel MD codes based on graphics processing units (GPU) are developed to enable large-scale MD simulations with multi-million atoms. In addition, an advanced interaction potential which reproduces brittle fracture much more accurately is adopted. As a result, the direct MD simulation of brittle–ductile Cutting Mode transition is realised for the first time under practical undeformed chip thicknesses. The MD-Modelled critical undeformed chip thickness is verified by a plunge Cutting experiment. The MD Modelling shows that tensile stress exists around the Cutting zone and increases with undeformed chip thickness, which finally induces brittle fractures. The location of crack formation and direction of propagation varies with undeformed chip thickness in the MD simulations, which agrees with the surface morphologies of the taper groove produced by the plunge Cutting experiment. This study contributes significantly to the understanding of the details involved in the brittle–ductile Cutting Mode transition.
To S - One of the best experts on this subject based on the ideXlab platform.
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A study of mechanics in brittle-ductile Cutting Mode transition
'MDPI AG', 2018Co-Authors: Xiao G, Ren M, To SAbstract:This paper presents an investigation of the mechanism of the brittle-ductile Cutting Mode transition from the perspective of the mechanics. A mechanistic Model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile Mode deformation is to follow the elastic stage. It is revealed that, the distance of tool advancement required to induce the same level of compressive stress decreases with undeformed chip thickness, and thereby the tensile stress below and behind the tool decreases with undeformed chip thickness. As a result, the tensile stress becomes lower than the critical tensile stress for brittle fracture when the undeformed chip thickness becomes sufficiently small, enabling the brittle-ductile Cutting Mode transition. The finite element method is employed to verify the analysis of the mechanics on a typical brittle material 6H silicon carbide, and confirmed that the distance of the tool advancement required to induce the same level of compressive stress becomes smaller when the undeformed chip thickness decreases, and consequently smaller tensile stress is induced below and behind the tool. The critical undeformed chip thicknesses for brittle-ductile Cutting Mode transition are estimated according to the proposed mechanics, and are verified by plunge Cutting experiments in a few crystal directions. This study should contribute to better understanding of the mechanism of brittle-ductile Cutting Mode transition and the ultra-precision machining of brittle materials.Department of Industrial and Systems Engineering2017-2018 > Academic research: refereed > Publication in refereed journal201808 bcr
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Effects of non-amorphizing hydrogen ion implantation on anisotropy in micro Cutting of silicon
Elsevier, 2015Co-Authors: Gb Xiao, To S, Ev JelenkovićAbstract:Modification of semiconductors by ion implantation is a promising technology for improving their machinability. As well as ion implantation that induce amorphization, non-amorphizing ion implantation is also reported to improve the machinability of silicon. However, the anisotropy in micro Cutting of crystalline silicon modified by non-amorphizing ion implantation is not clear. In this study, hydrogen is implanted in (001) silicon wafer with implantation energies and doses up to 175 KeV and 3 × 1016 cm-2, respectively. Transmission electron microscopy, numerical simulations and X-ray diffraction are carried out to confirm that point defects and strain are introduced by the implantation, and that crystalline damage is below the amorphization level. Plunge Cutting experiments in two crystal directions are performed to study the effects of limited crystal damage induced by ion implantation on the anisotropy in micro Cutting of silicon. The plunge Cutting experiments show that the anisotropic behaviour is significantly changed. The critical undeformed chip thickness (CUCT) in the direction with lower CUCT before implantation exceeds that in the other direction after implantation. The ductile-regime Cutting force is significantly reduced in one direction, while nearly un-affected in the other direction. The results are discussed from the perspective of the effects of ion implantation on the interaction between restricted slip systems. In addition, it is found that the scenarios of brittle-ductile Cutting Mode transition are significantly different in the and directions for both implanted and bare silicon, and the mechanisms are discussed from the perspective of the anisotropic cleavage systems.Department of Industrial and Systems Engineerin
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Molecular dynamics Modelling of brittle-ductile Cutting Mode transition : case study on silicon carbide
Elsevier, 2015Co-Authors: Gb Xiao, To S, Gq ZhangAbstract:The mechanism of brittle-ductile Cutting Mode transition has received much attention over the past two decades. Due to the difficulties in directly observing the Cutting zone during the brittle-ductile Cutting Mode transition by experimental techniques, many molecular dynamics (MD) studies have been conducted to investigate the atomicscale details of the phenomena, e.g. phase transformation, stress distribution and crack initiation, mostly under nanoscale undeformed chip thicknesses. A research gap is that direct MD Modelling of the transition under practical undeformed chip thicknesses was not achieved in previous studies, due to the limitations in both computation capability and interaction potential. Important details of the transition under practical undeformed chip thicknesses thereby remain unclear, e.g. the location of crack formation and the stress distribution. In this study, parallel MD codes based on graphics processing units (GPU) are developed to enable large-scale MD simulations with multi-million atoms. In addition, an advanced interaction potential which reproduces brittle fracture much more accurately is adopted. As a result, the direct MD simulation of brittle-ductile Cutting Mode transition is realised for the first time under practical undeformed chip thicknesses. The MD-Modelled critical undeformed chip thickness is verified by a plunge Cutting experiment. The MD Modelling shows that tensile stress exists around the Cutting zone and increases with undeformed chip thickness, which finally induces brittle fractures. The location of crack formation and direction of propagation varies with undeformed chip thickness in the MD simulations, which agrees with the surface morphologies of the taper groove produced by the plunge Cutting experiment. This study contributes significantly to the understanding of the details involved in the brittle-ductile Cutting Mode transition.Department of Industrial and Systems Engineerin
Mingjun Ren - One of the best experts on this subject based on the ideXlab platform.
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a study of mechanics in brittle ductile Cutting Mode transition
Micromachines, 2018Co-Authors: Gaobo Xiao, Mingjun RenAbstract:This paper presents an investigation of the mechanism of the brittle–ductile Cutting Mode transition from the perspective of the mechanics. A mechanistic Model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile Mode deformation is to follow the elastic stage. It is revealed that, the distance of tool advancement required to induce the same level of compressive stress decreases with undeformed chip thickness, and thereby the tensile stress below and behind the tool decreases with undeformed chip thickness. As a result, the tensile stress becomes lower than the critical tensile stress for brittle fracture when the undeformed chip thickness becomes sufficiently small, enabling the brittle–ductile Cutting Mode transition. The finite element method is employed to verify the analysis of the mechanics on a typical brittle material 6H silicon carbide, and confirmed that the distance of the tool advancement required to induce the same level of compressive stress becomes smaller when the undeformed chip thickness decreases, and consequently smaller tensile stress is induced below and behind the tool. The critical undeformed chip thicknesses for brittle–ductile Cutting Mode transition are estimated according to the proposed mechanics, and are verified by plunge Cutting experiments in a few crystal directions. This study should contribute to better understanding of the mechanism of brittle–ductile Cutting Mode transition and the ultra-precision machining of brittle materials.
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A Study of Mechanics in Brittle–Ductile Cutting Mode Transition
MDPI AG, 2018Co-Authors: Gaobo Xiao, Mingjun RenAbstract:This paper presents an investigation of the mechanism of the brittle–ductile Cutting Mode transition from the perspective of the mechanics. A mechanistic Model is proposed to analyze the relationship between undeformed chip thickness, deformation, and stress levels in the elastic stage of the periodic chip formation process, regarding whether brittle or ductile Mode deformation is to follow the elastic stage. It is revealed that, the distance of tool advancement required to induce the same level of compressive stress decreases with undeformed chip thickness, and thereby the tensile stress below and behind the tool decreases with undeformed chip thickness. As a result, the tensile stress becomes lower than the critical tensile stress for brittle fracture when the undeformed chip thickness becomes sufficiently small, enabling the brittle–ductile Cutting Mode transition. The finite element method is employed to verify the analysis of the mechanics on a typical brittle material 6H silicon carbide, and confirmed that the distance of the tool advancement required to induce the same level of compressive stress becomes smaller when the undeformed chip thickness decreases, and consequently smaller tensile stress is induced below and behind the tool. The critical undeformed chip thicknesses for brittle–ductile Cutting Mode transition are estimated according to the proposed mechanics, and are verified by plunge Cutting experiments in a few crystal directions. This study should contribute to better understanding of the mechanism of brittle–ductile Cutting Mode transition and the ultra-precision machining of brittle materials
Asif Iqbal - One of the best experts on this subject based on the ideXlab platform.
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a sustainability comparison between conventional and high speed machining
Journal of Cleaner Production, 2015Co-Authors: Khalid A Alghamdi, Asif IqbalAbstract:Abstract In the 1990s, the industrial application of high-speed machining achieved enormous success because of its favorable characteristics such as high productivity, better work quality, and ease of machining thin-walled structures. With fast changing emphasis of the world's manufacturing sector towards environmental benignity, the issue of sustainability with regard to application of high-speed machining becomes pivotal. The article presents an experimental investigation regarding comparison of conventional machining and high-speed machining with respect to sustainability measures. A set of 64 grooving experiments was performed on two tempers each of a high-strength low-alloy steel and a heat treatable titanium alloy. The experimental design focused on studying the effects of Cutting Mode (conventional/high-speed machining), Cutting speed levels for each of the two Modes, feed rate, and minimum quantity lubrication on tool life, specific Cutting energy, productivity, process cost, and machining forces. It was found that the choice between the two machining Modes is highly sensitive with respect to manufacturing sustainability. The conventional machining Mode was found to be comparatively economical, while the high-speed machining Mode significantly outperformed the other in terms of low specific energy consumption and high productivity. The article asserts that high speed machining can completely surpass conventional machining as the sustainable way of metal Cutting if the ways could be found to curb excessive tool damage observable at high Cutting speeds.
