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Subra Suresh - One of the best experts on this subject based on the ideXlab platform.
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Repeated Frictional Sliding properties of copper containing nanoscale twins
Scripta Materialia, 2012Co-Authors: Aparna Singh, Nairong Tao, Ming Dao, Subra SureshAbstract:Bulk dynamic plastic deformation (DPD) materials comprise a composite structure of nanoscale twin bundles and nanoscale grains. The tribological properties of DPD-processed pure nano-Cu have been investigated in this study and compared with conventional coarse-grained (CG) Cu under both monotonic and repeated Frictional Sliding. We demonstrate that DPD nano-Cu and CG Cu exhibit steady-state mechanical characteristics after repeated Frictional Sliding that are similar to those seen in nanotwinned (NT) Cu produced by pulsed electrodeposition. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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A new method for evaluating the plastic properties of materials through instrumented Frictional Sliding tests
Acta Materialia, 2010Co-Authors: S C Bellemare, Ming Dao, Subra SureshAbstract:Frictional normal contact probing methods involving instrumented, depth-sensing indentation can be used to estimate the mechanical properties of small-volume structures and materials such as thin films and components of micro-electro-mechanical systems. This paper describes a new method for estimating the plastic properties, i.e. the yield strength and strain hardening exponent, of ductile materials from the topography of scratches formed by a conical tip during an instrumented, depth-sensing Frictional Sliding test. The proposed reverse analysis (or inverse analysis) uses dimensionless functions derived from computational simulations to extract plastic properties from an instrumented scratch response performed on a standard, commercially available instrument. Sensitivity analysis indicates that an experimental error of 5% in the scratch hardness or the pile-up height induces an error of
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Steady-state Frictional Sliding contact on surfaces of plastically graded materials
Acta Materialia, 2009Co-Authors: Anamika Prasad, Ming Dao, Subra SureshAbstract:Abstract Tailored gradation in elastic–plastic properties is known to offer avenues for suppressing surface damage during normal indentation and Sliding contact. In tribological applications, Sliding contact analysis provides a more representative mechanism for fundamental understanding and design as it offers a tool to test materials under conditions of controlled abrasive wear. However, no such study exists for plastically graded materials, although the Sliding behavior for elastically graded materials has been reasonably well understood. This study has established a systematic methodology to quantify the mechanics of steady-state Frictional Sliding response for a plastically graded material. Specifically, the effect of linear gradient in yield stress on the Frictional Sliding response is examined through parametric finite-element (FEM) computation of the instrumented scratch test. Gradients in yield strength affect both the load carrying capacity of the surface and its pile-up around the Sliding indenter. An increase in yield strength with distance beneath the surface shifts the peak values of von Mises stress below the surface, thus improving the resistance of the surface to onset of plasticity and damage. For a given elastic–plastic property, an increasing yield strength gradient causes a reduction in total apparent friction through a reduction in the ploughing coefficient. The contact-load-bearing capacity of plastically graded surfaces follows a similar trend during indentation and scratch. However, significant differences between the pile-up and the friction response are observed between normal indentation and steady-state Frictional Sliding. In particular, an increase in interfacial friction is found to cause an increase in pile-up during scratch, while it causes a decrease in pile-up during indentation. The implications of the present results to the design of graded surfaces are discussed.
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The Frictional Sliding response of elasto-plastic materials in contact with a conical indenter
International Journal of Solids and Structures, 2007Co-Authors: S C Bellemare, Ming Dao, Subra SureshAbstract:Abstract Over the past decade, many computational studies have explored the mechanics of normal indentation. Quantitative relationships have been well established between the load–displacement hysteresis response and material properties. By contrast, very few studies have investigated broad quantitative aspects of the effects of material properties, especially plastic deformation characteristics, on the Frictional Sliding response of metals and alloys. The response to instrumented, depth-sensing Frictional Sliding, hereafter referred to as a scratch test, could potentially be used for material characterization. In addition, it could reproduce a basic tribological event, such as asperity contact and deformation, at different length scales for the multi-scale modeling of wear processes. For these reasons, a comprehensive study was undertaken to investigate the effect of elasto-plastic properties, such as flow strength and strain hardening, on the response to steady-state Frictional Sliding. Dimensional analysis was used to define scaling variables and universal functions. The dependence of these functions on material properties was assessed through a detailed parametric study using the finite element method. The strain hardening exponent was found to have a greater influence on the scratch hardness and the pile-up height during Frictional Sliding than observed in frictionless normal indentation. When normalized by the penetration depth, the pile-up height can be up to three times larger in Frictional Sliding than in normal indentation. Furthermore, in contrast to normal indentation, sink-in is not observed during Frictional Sliding over the wide range of material properties examined. Finally, friction between indenter and indented material was introduced in the finite element model, and quantitative relationships were also established for the limited effects of plastic strain hardening and yield strength on the overall friction coefficient. Aspects of the predictions of computational simulations were compared with experiments on carefully selected metallic systems in which the plastic properties were systematically controlled. The level of accuracy of the predicted Frictional response is also assessed by recourse to the finite element method and by comparison with experiment.
Jay Fineberg - One of the best experts on this subject based on the ideXlab platform.
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Frictional Sliding without geometrical reflection symmetry
arXiv: Materials Science, 2016Co-Authors: Michael Aldam, Jay Fineberg, Yohai Barsinai, Ilya Svetlizky, Efim A Brener, Eran BouchbinderAbstract:The dynamics of Frictional interfaces play an important role in many physical systems spanning a broad range of scales. It is well-known that Frictional interfaces separating two dissimilar materials couple interfacial slip and normal stress variations, a coupling that has major implications on their stability, failure mechanism and rupture directionality. In contrast, interfaces separating identical materials are traditionally assumed not to feature such a coupling due to symmetry considerations. We show, combining theory and experiments, that interfaces which separate bodies made of macroscopically identical materials, but lack geometrical reflection symmetry, generically feature such a coupling. We discuss two applications of this novel feature. First, we show that it accounts for a distinct, and previously unexplained, experimentally observed weakening effect in Frictional cracks. Second, we demonstrate that it can destabilize Frictional Sliding which is otherwise stable. The emerging framework is expected to find applications in a broad range of systems.
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Frictional Sliding with geometrically broken reflection symmetry
arXiv: Materials Science, 2016Co-Authors: Michael Aldam, Jay Fineberg, Ilya Svetlizky, Efim A Brener, Yohai Bar-sinai, Eran BouchbinderAbstract:The dynamics of Frictional interfaces play an important role in many physical systems spanning a broad range of scales. It is well-known that Frictional interfaces separating two dissimilar materials couple interfacial slip and normal stress variations, a coupling that has major implications on their stability, failure mechanism and rupture directionality. In contrast, interfaces separating identical materials are traditionally assumed not to feature such a coupling due to symmetry considerations. We show, combining theory and experiments, that interfaces which separate bodies made of identical materials, but lack geometric reflection symmetry, generically feature such a coupling. We discuss two applications of this novel feature. First, we show that it accounts for a distinct and previously unexplained weakening effect in Frictional cracks observed experimentally. Second, we demonstrate that it can destabilize Frictional Sliding which is otherwise stable. The emerging framework is expected to find applications in a broad range of systems.
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Frictional Sliding without geometrical reflection symmetry
Physical Review X, 2016Co-Authors: Michael Aldam, Jay Fineberg, Yohai Barsinai, Ilya Svetlizky, Efim A Brener, Eran BouchbinderAbstract:Friction plays a key role in everyday life. A new study shows that Frictional resistance depends on the geometry of the bodies in Frictional contact.
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visualizing stick slip experimental observations of processes governing the nucleation of Frictional Sliding
Journal of Physics D, 2009Co-Authors: Shmuel M Rubinstein, Gil Cohen, Jay FinebergAbstract:Understanding the dynamics of Frictional motion is essential to fields ranging from nano-machines to the study of earthquakes. Frictional motion involves a huge range of time and length scales, coupling the elastic fields of two blocks under stress to the dynamics of the myriad interlocking microscopic contacts that form the interface at their plane of separation. In spite of the immense practical and fundamental importance of friction, many aspects of the basic physics of the problem are still not well understood. One such aspect is the nucleation of Frictional motion commonly referred to as the transition from static to dynamic friction. Here we review experimental studies of dynamical aspects of Frictional Sliding. We focus mainly on recent advances in real-time visualization of the real area of contact along large spatially extended interfaces and the importance of rapid fracture-like processes that appear at the onset of Frictional instability.
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Visualizing stick–slip: experimental observations of processes governing the nucleation of Frictional Sliding
Journal of Physics D: Applied Physics, 2009Co-Authors: Shmuel Rubinstein, Gil Cohen, Jay FinebergAbstract:Understanding the dynamics of Frictional motion is essential to fields ranging from nano-machines to the study of earthquakes. Frictional motion involves a huge range of time and length scales, coupling the elastic fields of two blocks under stress to the dynamics of the myriad interlocking microscopic contacts that form the interface at their plane of separation. In spite of the immense practical and fundamental importance of friction, many aspects of the basic physics of the problem are still not well understood. One such aspect is the nucleation of Frictional motion commonly referred to as the transition from static to dynamic friction. Here we review experimental studies of dynamical aspects of Frictional Sliding. We focus mainly on recent advances in real-time visualization of the real area of contact along large spatially extended interfaces and the importance of rapid fracture-like processes that appear at the onset of Frictional instability.
George G. Adams - One of the best experts on this subject based on the ideXlab platform.
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Dilatational and shear waves induced by the Frictional Sliding of two elastic half-spaces
International Journal of Engineering Science, 2001Co-Authors: Mikhail Nosonovsky, George G. AdamsAbstract:The nominally steady-state Frictional Sliding of two flat elastic half-spaces is investigated. It is shown that steady Sliding is compatible with the formation of a pair of body waves (dilatational and shear) in each body radiated away from the Sliding interface. Each wave propagates at a different angle such that the trace velocities along the interface are equal. The angles of propagation are determined by the material properties and by the coefficient of Sliding friction. The wave amplitudes are subject only to the restriction that the perturbations in interface contact pressure and relative tangential velocity satisfy the inequality constraints for unilateral Sliding contact. Furthermore these waves are shown to exist for a variety of Frictional Sliding laws, including speed-dependent and speed-independent friction. Finally it is shown that a slip pulse can exist which allows the two bodies to undergo relative tangential motion with a ratio of applied shear to normal stress which is less than the friction coefficient.
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Steady-State Frictional Sliding of Two Elastic Bodies With a Wavy Contact Interface
Journal of Tribology, 2000Co-Authors: Mikhail Nosonovsky, George G. AdamsAbstract:Dry Frictional Sliding of two elastic bodies, one of which has a periodic wavy surface, is considered, Such a model represents the Frictional Sliding of two nominally flat surfaces, one of which has periodically spaced asperities. The dependence of the true contact area on loading is analyzed by using the plane strain theory of elasticity. Fourier series and integral transform techniques are applied to reduce the problem to an integral equation which is solved using a series of Jacobi polynomials. For steady-state dynamic Frictional Sliding with given values of the friction coefficient, materials constants, and Sliding velocity, the dependence of the contact zone length on the remotely applied tractions is determined. The results indicate a decrease of the minimum applied traction required to close the gap between the bodies, with an increase of the friction coefficient and/or the Sliding velocity. A resonance exists as the Sliding velocity approaches the Rayleigh wave speed of the flat body.
Sergei V. Kalinin - One of the best experts on this subject based on the ideXlab platform.
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Piezoelectric indentation of a flat circular punch accompanied by Frictional Sliding and applications to scanning probe microscopy
International Journal of Engineering Science, 2009Co-Authors: Arty Makagon, Mark Kachanov, Edgar Karapetian, Sergei V. KalininAbstract:Indentation of a piezoelectric half-space by a flat circular indenter accompanied by Frictional Sliding is considered. Full-field electroelastic solutions in elementary functions are obtained. The solution is based on the correspondence principle between elastic and piezoelectric problems. Stiffness relations between applied load and resulting displacement are given in elementary functions. In conjunction with the conical and spherical solutions, given previously by Makagon et al. [A. Makagon, M. Kachanov, S.V. Kalinin, E. Karapetian, Indentation and Frictional Sliding of spherical and conical punches into piezoelectric half-space, Physical Review B 76 (2007) 064115 (14)], this work completes the set of limiting cases of tip geometries utilized in lateral force microscopy (LFM) technology. Implications for quantitative interpretation of scanning probe microscopy (SPM) data and tribological data are analyzed.
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Indentation of spherical and conical punches into piezoelectric half-space with Frictional Sliding: Applications to scanning probe microscopy
Physical Review B, 2007Co-Authors: Arty Makagon, Mark Kachanov, Sergei V. Kalinin, Edgar KarapetianAbstract:A proper quantitative interpretation of scanning probe microscopy (SPM) experiments requires solutions for both normal and tangential indentations of punches into a piezoelectric material. Such indentation solutions, their dependence on the indenter shape, and implications for SPM are considered here. More specifically, indentation of the spherical and conically sharp indenters into a piezoelectric half-space accompanied by Frictional Sliding is addressed. The tangential part of the problem, which involves friction, is solved to complement the solution of the normal indentation problem obtained earlier. Exact stiffness relations between vertical load, tangential displacement, and material properties are obtained. The piezoelectric coupling is found to have a relatively weak effect on lateral contact stiffness. In contrast, the contact area depends noticeably on the tangential effects. The full electroelastic fields are derived in elementary functions and their implications are discussed.
Ming Dao - One of the best experts on this subject based on the ideXlab platform.
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Repeated Frictional Sliding properties of copper containing nanoscale twins
Scripta Materialia, 2012Co-Authors: Aparna Singh, Nairong Tao, Ming Dao, Subra SureshAbstract:Bulk dynamic plastic deformation (DPD) materials comprise a composite structure of nanoscale twin bundles and nanoscale grains. The tribological properties of DPD-processed pure nano-Cu have been investigated in this study and compared with conventional coarse-grained (CG) Cu under both monotonic and repeated Frictional Sliding. We demonstrate that DPD nano-Cu and CG Cu exhibit steady-state mechanical characteristics after repeated Frictional Sliding that are similar to those seen in nanotwinned (NT) Cu produced by pulsed electrodeposition. (C) 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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a new method for evaluating the plastic properties of materials through instrumented Frictional Sliding tests
Acta Materialia, 2010Co-Authors: S C Bellemare, Ming Dao, S SureshAbstract:Frictional normal contact probing methods involving instrumented, depth-sensing indentation can be used to estimate the mechanical properties of small-volume structures and materials such as thin films and components of micro-electro-mechanical systems. This paper describes a new method for estimating the plastic properties, i.e. the yield strength and strain hardening exponent, of ductile materials from the topography of scratches formed by a conical tip during an instrumented, depth-sensing Frictional Sliding test. The proposed reverse analysis (or inverse analysis) uses dimensionless functions derived from computational simulations to extract plastic properties from an instrumented scratch response performed on a standard, commercially available instrument. Sensitivity analysis indicates that an experimental error of 5% in the scratch hardness or the pile-up height induces an error of <22% in the estimated strain hardening exponent. Laboratory experiments illustrate how two aluminum alloy tempers of the same indentation hardness have significantly different pile-up as a result of different strain hardening. Comparative results between the Frictional Sliding test and traditional tensile tests showed reasonable agreement for a total of 11 metallic alloys evaluated. These results confirm the potential usefulness of the proposed method as an engineering tool to probe plastic properties of small-volume materials and confined structures where it is difficult to obtain reliable estimates of mechanical properties by other means.
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A new method for evaluating the plastic properties of materials through instrumented Frictional Sliding tests
Acta Materialia, 2010Co-Authors: S C Bellemare, Ming Dao, Subra SureshAbstract:Frictional normal contact probing methods involving instrumented, depth-sensing indentation can be used to estimate the mechanical properties of small-volume structures and materials such as thin films and components of micro-electro-mechanical systems. This paper describes a new method for estimating the plastic properties, i.e. the yield strength and strain hardening exponent, of ductile materials from the topography of scratches formed by a conical tip during an instrumented, depth-sensing Frictional Sliding test. The proposed reverse analysis (or inverse analysis) uses dimensionless functions derived from computational simulations to extract plastic properties from an instrumented scratch response performed on a standard, commercially available instrument. Sensitivity analysis indicates that an experimental error of 5% in the scratch hardness or the pile-up height induces an error of
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Steady-state Frictional Sliding contact on surfaces of plastically graded materials
Acta Materialia, 2009Co-Authors: Anamika Prasad, Ming Dao, Subra SureshAbstract:Abstract Tailored gradation in elastic–plastic properties is known to offer avenues for suppressing surface damage during normal indentation and Sliding contact. In tribological applications, Sliding contact analysis provides a more representative mechanism for fundamental understanding and design as it offers a tool to test materials under conditions of controlled abrasive wear. However, no such study exists for plastically graded materials, although the Sliding behavior for elastically graded materials has been reasonably well understood. This study has established a systematic methodology to quantify the mechanics of steady-state Frictional Sliding response for a plastically graded material. Specifically, the effect of linear gradient in yield stress on the Frictional Sliding response is examined through parametric finite-element (FEM) computation of the instrumented scratch test. Gradients in yield strength affect both the load carrying capacity of the surface and its pile-up around the Sliding indenter. An increase in yield strength with distance beneath the surface shifts the peak values of von Mises stress below the surface, thus improving the resistance of the surface to onset of plasticity and damage. For a given elastic–plastic property, an increasing yield strength gradient causes a reduction in total apparent friction through a reduction in the ploughing coefficient. The contact-load-bearing capacity of plastically graded surfaces follows a similar trend during indentation and scratch. However, significant differences between the pile-up and the friction response are observed between normal indentation and steady-state Frictional Sliding. In particular, an increase in interfacial friction is found to cause an increase in pile-up during scratch, while it causes a decrease in pile-up during indentation. The implications of the present results to the design of graded surfaces are discussed.
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The Frictional Sliding response of elasto-plastic materials in contact with a conical indenter
International Journal of Solids and Structures, 2007Co-Authors: S C Bellemare, Ming Dao, Subra SureshAbstract:Abstract Over the past decade, many computational studies have explored the mechanics of normal indentation. Quantitative relationships have been well established between the load–displacement hysteresis response and material properties. By contrast, very few studies have investigated broad quantitative aspects of the effects of material properties, especially plastic deformation characteristics, on the Frictional Sliding response of metals and alloys. The response to instrumented, depth-sensing Frictional Sliding, hereafter referred to as a scratch test, could potentially be used for material characterization. In addition, it could reproduce a basic tribological event, such as asperity contact and deformation, at different length scales for the multi-scale modeling of wear processes. For these reasons, a comprehensive study was undertaken to investigate the effect of elasto-plastic properties, such as flow strength and strain hardening, on the response to steady-state Frictional Sliding. Dimensional analysis was used to define scaling variables and universal functions. The dependence of these functions on material properties was assessed through a detailed parametric study using the finite element method. The strain hardening exponent was found to have a greater influence on the scratch hardness and the pile-up height during Frictional Sliding than observed in frictionless normal indentation. When normalized by the penetration depth, the pile-up height can be up to three times larger in Frictional Sliding than in normal indentation. Furthermore, in contrast to normal indentation, sink-in is not observed during Frictional Sliding over the wide range of material properties examined. Finally, friction between indenter and indented material was introduced in the finite element model, and quantitative relationships were also established for the limited effects of plastic strain hardening and yield strength on the overall friction coefficient. Aspects of the predictions of computational simulations were compared with experiments on carefully selected metallic systems in which the plastic properties were systematically controlled. The level of accuracy of the predicted Frictional response is also assessed by recourse to the finite element method and by comparison with experiment.
