The Experts below are selected from a list of 61041 Experts worldwide ranked by ideXlab platform
R Komanduri - One of the best experts on this subject based on the ideXlab platform.
-
thermal modeling of the metal cutting process part iii temperature rise distribution due to the combined effects of Shear Plane heat source and the tool chip interface frictional heat source
International Journal of Mechanical Sciences, 2001Co-Authors: R Komanduri, Zhen Bing HouAbstract:Abstract This paper is Part III of a 3-part series on the Thermal Modeling of the Metal Cutting Process. In Part I (Komanduri, Hou, International Journal of Mechanical Sciences 2000;42(9):1715–1752), the temperature rise distribution in the workmaterial and the chip due to Shear Plane heat source alone was presented using modified Hahn's moving oblique band heat source solution with appropriate image sources for the Shear Plane (Hahn, Proceedings of the First US National Congress of Applied Mechanics 1951. p. 661–6). In Part II (Komanduri, Hou, International Journal of Mechanical Sciences 2000;43(1):57–88), the temperature rise distribution due to the frictional heat source at the tool–chip interface alone is considered using the modified Jaeger's moving-band (in the chip) and stationary rectangular (in the tool) heat source solutions (Jaeger, Proceedings of the Royal Society of New SouthWales, 1942;76:203–24; Carlsaw, Jaeger. Conduction of heat in solids, Oxford, UK: Oxford University Press, 1959) with appropriate image sources and non-uniform distribution of heat intensity. The matching of the temperature rise distribution at the tool–chip contact interface for a moving-band (chip) and a stationary rectangular heat source (tool) was accomplished using functional analysis technique, originally proposed by Chao and Trigger (Transactions of ASME 1955;75:1107–21). This paper (Part III) deals with the temperature rise distribution in metal cutting due to the combined effect of Shear Plane heat source in the primary Shear zone and frictional heat source at the tool–chip interface. The basic approach is similar to that presented in Parts I and II. The model was applied to two cases of metal cutting, namely, conventional machining of steel with a carbide tool at high Peclet numbers (≈5–20) using data from Chao and Trigger (Transactions of ASME 1955;75:1107–21) and ultraprecision machining of aluminum using a single-crystal diamond at low Peclet numbers (≈0.5) using data from Ueda et al. (Annals of CIRP1998;47(1):41–4). The analytical results were found to be in good agreement with the experimental results, thus validating the model. Using relevant computer programs developed for the analytical solutions, the computation of the temperature rise distributions in the workmaterial, the chip, and the tool were found. The analytical method was found to be much easier, faster, and more accurate to use than the numerical methods used (e.g., Dutt, Brewer, International Journal of Production Research 1964;4:91–114; Tay, Stevenson, de Vahl Davis, Proceedings of the Institution of Mechanical Engineers (London) 1974;188:627). The analytical model also provides a better physical understanding of the thermal process in metal cutting.
-
thermal modeling of the metal cutting process part i temperature rise distribution due to Shear Plane heat source
International Journal of Mechanical Sciences, 2000Co-Authors: R KomanduriAbstract:Abstract The model of an oblique band heat source moving in the direction of cutting, first introduced by Hahn (Proceedings of First U.S. National Congress of Applied Mechanics 1951. p. 661–6) for an infinite medium in 1951 and subsequently modified by Chao and Trigger (Transactions of ASME 1953;75:109–20) in 1953 for a semi-infinite medium, is extended in this investigation by including appropriate image heat sources. It is used for the determination of the temperature rise distribution in the chip and the work material near the Shear Plane caused by the main Shear Plane heat source in orthogonal machining of a continuous chip. A new approach is taken in that the analysis is made in two separate parts, namely, the workmaterial side and the chip side of the Shear Plane and then combined. The workmaterial (or the chip) is extended past the Shear Plane as an imaginary region for continuity to determine the temperature distribution in the workmaterial (or the chip) near the Shear Plane. The imaginary regions are the regions either of the workmaterial that was cut by the cutting tool prior to this instance and became the chip or will be cut by the cutting tool prior to becoming the chip. An appropriate image heat source with the same intensity as the Shear Plane heat source is considered for each case. The temperature distributions in the chip and the workmaterial were determined separately by this method and combined to obtain isotherms of the total temperature distribution (and not merely the average temperatures). It appears that the significance of Hahn's ingenious idea and his general solution have not been fully appreciated; instead, an approximate approach involving heat partition between the chip and the work was frequently used (Trigger and Chao. Transactions of ASME 1951;73:57–68; Loewen and Shaw. Transactions of ASME 1954;71:217–31; Leone. Transactions of ASME 1954;76:121–5; Nakayama. Bulletin of the Faculty of Engineering National University of Yokohama, Yokohama, Japan, 1956;21:1–5; Boothroyd. Proceedings of the Institution of Mechanical Engineers (Lon) 1963;177(29):789–810). It may be noted that in utilizing Hahn's modified solution, it is not necessary to make an explicit a priori assumption regarding partitioning of heat between the workmaterial and the chip, as was common in most prior work. Instead, this information is provided as part of the solution. The results obtained with the exact analysis were compared with other methods using the experimental data available in the literature to point out some of the discrepancies in the simplified models. It may be pointed out that these models assume the temperature rise at the chip–tool interface to be nearly uniform and equals the average temperature rise in this volume. A comparison of the calculated temperature rise by these methods with the exact analysis indicates that the differences can be quite significant (∼50% or higher). It is hoped that future researchers would recognize the significance and the versatility of the exact analysis in determining the temperature distribution in the Shear zone in metal cutting.
Lea Gest - One of the best experts on this subject based on the ideXlab platform.
-
Recrystallization processes, microstructure and crystallographic preferred orientation evolution in polycrystalline ice during high-temperature simple Shear
The Cryosphere, 2019Co-Authors: B Journaux, Thomas Chauve, Maurine Montagnat, Andrea Tommasi, Fabrice Barou, David Mainprice, Lea GestAbstract:Torsion experiments were performed in polycrys-talline ice at high temperature (0.97 T m) to reproduce the simple Shear kinematics that are believed to dominate in ice streams and at the base of fast-flowing glaciers. As clearly documented more than 30 years ago, under simple Shear ice develops a two-maxima c axis crystallographic preferred orientation (CPO), which evolves rapidly into a single cluster CPO with a c axis perpendicular to the Shear Plane. Dynamic recrystallization mechanisms that occur in both laboratory conditions and naturally deformed ice are likely candidates to explain the observed CPO evolution. In this study, we use electron backscatter diffraction (EBSD) and automatic ice texture analyzer (AITA) to characterize the mechanisms accommodating deformation, the stress and strain het-erogeneities that form under torsion of an initially isotropic polycrystalline ice sample at high temperature, and the role of dynamic recrystallization in accommodating these het-erogeneities. These analyses highlight an interlocking mi-crostructure, which results from heterogeneity-driven serrated grain boundary migration, and sub-grain boundaries composed of dislocations with a [c]-component Burgers vector , indicating that strong local stress heterogeneity develops, in particular, close to grain boundaries, even at high temperature and high finite Shear strain. Based on these observations, we propose that nucleation by bulging, assisted by sub-grain boundary formation and followed by grain growth, is a very likely candidate to explain the progressive disappearance of the c axis CPO cluster at low angle to the Shear Plane and the stability of the one normal to it. We therefore strongly support the development of new polycrystal plasticity models limiting dislocation slip on non-basal slip systems and allowing for efficient accommodation of strain incompatibilities by an association of bulging and formation of sub-grain boundaries with a significant [c] component.
-
microstructure and texture evolution in polycrystalline ice during hot torsion impact of intragranular strain and recrystallization processes
The Cryosphere Discussions, 2018Co-Authors: B Journaux, Thomas Chauve, Maurine Montagnat, Andrea Tommasi, Fabrice Barou, David Mainprice, Lea GestAbstract:Abstract. Torsion experiments were performed in polycrystalline ice at high temperature (0.97 ⋅ T m ) to reproduce simple Shear conditions close to those encountered in ice streams and at the base of fast flowing glaciers. As well documented more than 30 years ago (Hudleston, 1977; Bouchez and Duval, 1982), under simple Shear ice develops a two-maxima c-axis texture, which evolves rapidly into a single cluster texture with c-axis perpendicular to the Shear Plane. This evolution still lacks a physical explanation. Current viscoplastic modeling approaches on ice involving dislocation slip on multiple slip systems (basal pyramidal, and prismatic) fail to reproduce it. Dynamic recrystallization mechanisms that occur in both laboratory conditions and in natural setups are likely candidates to explain the texture evolution observed. In this study, we use Electron BackScattering Diffraction (EBSD) and Automatic Ice Texture Analyzer (AITA) to characterize the mechanisms accommodating deformation, the stress and strain heterogeneities that form under torsion of an initially isotropic polycrystalline ice sample at high temperature, and the role of dynamic recrystallization in accommodating these heterogeneities. These analyses highlight an interlocking microstructure, which results from heterogeneity-driven serrated grain boundary migration, and sub-grain boundaries composed by dislocations with [ c ]-component Burgers vector, indicating that strong local stress heterogeneity develops, even at high temperature and high finite Shear strain. Based on these observations, we propose that that nucleation by bulging, assisted by sub-grain boundary formation, is a very likely candidate to explain the progressive disappearance of the texture cluster at low angle to the Shear Plane and the stability of the one normal to it. We therefore strongly support the development of new models limiting dislocation slip on non-basal slip system and allowing for efficient polygonization by an association of bulging and formation of sub-grain boundaries with a significant [ c ]-component.
Eiji Usui - One of the best experts on this subject based on the ideXlab platform.
-
simulation of cutting process in peripheral milling by predictive cutting force model based on minimum cutting energy
International Journal of Machine Tools & Manufacture, 2010Co-Authors: Takashi Matsumura, Eiji UsuiAbstract:The cutting force and the chip flow direction in peripheral milling are predicted by a predictive force model based on the minimum cutting energy. The chip flow model in milling is made by piling up the orthogonal cuttings in the Planes containing the cutting velocities and the chip flow velocities. The cutting edges are divided into discrete segments and the Shear Plane cutting models are made on the segments in the chip flow model. In the peripheral milling, the Shear Plane in the cutting model cannot be completely made when the cutting point is near the workpiece surface. When the Shear Plane is restricted by the workpiece surface, the cutting energy is estimated taking into account the restricted length of the Shear Plane. The chip flow angle is determined so as to minimize the cutting energy. Then, the cutting force is predicted in the determined chip flow model corresponding to the workpiece shape. The cutting processes in the traverse and the contour millings are simulated as practical operations and the predicted cutting forces verified in comparison with the measured ones. Because the presented model determines the chip flow angle based on the cutting energy, the change in the chip flow angle can be predicted with the cutting model.
-
predictive cutting force model in complex shaped end milling based on minimum cutting energy
International Journal of Machine Tools & Manufacture, 2010Co-Authors: Takashi Matsumura, Eiji UsuiAbstract:A force model is presented to predict the cutting forces and the chip flow directions in cuttings with complex-shaped end mills such as ball end mills and roughing end mills. Three-dimensional chip flow in milling is interpreted as a piling up of the orthogonal cuttings in the Planes containing the cutting velocities and the chip flow velocities. Because the cutting thickness changes with the rotation angle of the edge in the milling process, the surface profile machined by the previous edge inclines with respect to the cutting direction. The chip flow model is made using the orthogonal cutting data with taking into account the inclination of the pre-machined surface. The chip flow direction is determined so as to minimize the cutting energy, which is the sum of the Shear energy on the Shear Plane and the friction energy on the rake face. Then, the cutting force is predicted for the chip flow model at the minimum cutting energy. The predicted chip flow direction changes not only with the local edge inclination but also with the cutting energy consumed in the Shear Plane cutting model. The cutting processes with a ball end mill and a roughing end mill are simulated to verify the predicted cutting forces in comparison with the measured cutting forces.
Zhen Bing Hou - One of the best experts on this subject based on the ideXlab platform.
-
thermal modeling of the metal cutting process part iii temperature rise distribution due to the combined effects of Shear Plane heat source and the tool chip interface frictional heat source
International Journal of Mechanical Sciences, 2001Co-Authors: R Komanduri, Zhen Bing HouAbstract:Abstract This paper is Part III of a 3-part series on the Thermal Modeling of the Metal Cutting Process. In Part I (Komanduri, Hou, International Journal of Mechanical Sciences 2000;42(9):1715–1752), the temperature rise distribution in the workmaterial and the chip due to Shear Plane heat source alone was presented using modified Hahn's moving oblique band heat source solution with appropriate image sources for the Shear Plane (Hahn, Proceedings of the First US National Congress of Applied Mechanics 1951. p. 661–6). In Part II (Komanduri, Hou, International Journal of Mechanical Sciences 2000;43(1):57–88), the temperature rise distribution due to the frictional heat source at the tool–chip interface alone is considered using the modified Jaeger's moving-band (in the chip) and stationary rectangular (in the tool) heat source solutions (Jaeger, Proceedings of the Royal Society of New SouthWales, 1942;76:203–24; Carlsaw, Jaeger. Conduction of heat in solids, Oxford, UK: Oxford University Press, 1959) with appropriate image sources and non-uniform distribution of heat intensity. The matching of the temperature rise distribution at the tool–chip contact interface for a moving-band (chip) and a stationary rectangular heat source (tool) was accomplished using functional analysis technique, originally proposed by Chao and Trigger (Transactions of ASME 1955;75:1107–21). This paper (Part III) deals with the temperature rise distribution in metal cutting due to the combined effect of Shear Plane heat source in the primary Shear zone and frictional heat source at the tool–chip interface. The basic approach is similar to that presented in Parts I and II. The model was applied to two cases of metal cutting, namely, conventional machining of steel with a carbide tool at high Peclet numbers (≈5–20) using data from Chao and Trigger (Transactions of ASME 1955;75:1107–21) and ultraprecision machining of aluminum using a single-crystal diamond at low Peclet numbers (≈0.5) using data from Ueda et al. (Annals of CIRP1998;47(1):41–4). The analytical results were found to be in good agreement with the experimental results, thus validating the model. Using relevant computer programs developed for the analytical solutions, the computation of the temperature rise distributions in the workmaterial, the chip, and the tool were found. The analytical method was found to be much easier, faster, and more accurate to use than the numerical methods used (e.g., Dutt, Brewer, International Journal of Production Research 1964;4:91–114; Tay, Stevenson, de Vahl Davis, Proceedings of the Institution of Mechanical Engineers (London) 1974;188:627). The analytical model also provides a better physical understanding of the thermal process in metal cutting.
Ali Fatemi - One of the best experts on this subject based on the ideXlab platform.
-
on the consideration of normal and Shear stress interaction in multiaxial fatigue damage analysis
International Journal of Fatigue, 2017Co-Authors: Nicholas R Gates, Ali FatemiAbstract:Abstract Due to the abundance of engineering components subjected to complex multiaxial loading histories, being able to accurately estimate fatigue damage under multiaxial stress states is a fundamental step in many fatigue life analyses. In this respect, the Fatemi-Socie (FS) critical Plane damage parameter has been shown to provide satisfactory fatigue life correlations for a variety of materials and loading conditions. In this parameter, Shear strain amplitude has a primary influence on fatigue damage and the maximum normal stress on the maximum Shear Plane has a secondary, but important, influence. Additionally, in order to preserve the unitless feature of strain, the maximum normal stress is normalized by the material yield strength. However, in examining some data from literature it was found that, in certain situations, the FS parameter can result in better fatigue life predictions if the maximum normal stress is normalized by the Shear stress range on the maximum Shear Plane instead. These data include uniaxial loadings with large tensile mean stress, and some combined axial-torsion load paths with different normal-Shear stress interactions. This modification to the FS parameter was investigated by using fatigue data from literature for 7075-T651 aluminum alloy and a ductile cast iron, as well as additional data from 2024-T3 aluminum alloy fatigue tests performed in this study.
