Melih Eriten | University of Wisconsin-Madison (original) (raw)
Papers by Melih Eriten
A model is presented that accounts for contact with a molecularly thin lubricant layer confined b... more A model is presented that accounts for contact with a molecularly thin lubricant layer confined between a rigid sphere and flat substrate. The sphere is moving at a high lateral velocity inducing high shear rates and a significant increase of lubricant viscosity. Interfacial slip is modeled based on experimental and molecular dynamics data and includes effects of lubricant morphology and chemistry. The model is used to interpret experimental measurements of viscosity and slip and express them as functions of shear rate. These ...
Nanotechnology, Jan 1, 2005
Abstract Breakdown voltage is a unique well-known indicator for gases. Previous work indicate t... more Abstract Breakdown voltage is a unique well-known indicator for gases. Previous work indicate that miniaturized gas ionization sensors, which are made up of two electrodes one of which accommodates vertically aligned carbon nanotubes (CNTs), reduce breakdown voltage thanks to electric ...
Journal of biomechanical engineering, Jan 1, 2009
In this paper, dynamical systems analysis and optimization tools are used to investigate the loca... more In this paper, dynamical systems analysis and optimization tools are used to investigate the local dynamic stability of periodic task-related motions of simple models of the lower-body musculoskeletal apparatus and to seek parameter values guaranteeing their stability. Several muscle models incorporating various active and passive elements are included and the notion of self-stabilization of the rigid-body dynamics through the imposition of musclelike actuation is investigated. It is found that self-stabilization depends both on muscle architecture and configuration as well as the properties of the reference motion. Additionally, antagonistic muscles (flexor-extensor muscle couples) are shown to enable stable motions over larger ranges in parameter space and that even the simplest neuronal feedback mechanism can stabilize the repetitive motions. The work provides a review of the necessary concepts of stability and a commentary on existing incorrect results that have appeared in literature on muscle self-stabilization.
Tribology Letters
Under the effects of high shear rate and confinement between solid surfaces, the behavior of a th... more Under the effects of high shear rate and confinement between solid surfaces, the behavior of a thin lubricant film deviates from that of the bulk, resulting in significant increases of lubricant viscosity and interfacial slip. A semi-empirical model accounting for the breakdown of continuum theory at the nanoscale is proposed-based on film morphology and chemistry from available experimental and molecular dynamics simulation data-to describe lubricant behavior under shear. Viscosity stiffening and interfacial slip models are introduced into the formulations of the normal (bearing) and shear forces acting on a sphere that moves within a thin lubricant film parallel to a rigid plane. The experimentally measured 'apparent' viscosity confounding the effects of both stiffening and slip is used to predict the hydrodynamic forces acting on a fully or partially submerged sphere for the purposes of describing lubricant contact in magnetic storage. The proposed sphere-on-flat model forms the basis of a future, dynamic contact with friction model that will account for lubricant contact in the context of molecularly thin lubricated rough surface contact.
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Journal of Tribology, Jan 1, 2010
Journal of Tribology, Jan 1, 2010
Asymmetric height distribution in surface roughness is important in many engineering surfaces, su... more Asymmetric height distribution in surface roughness is important in many engineering surfaces, such as in constant velocity (CV) joints, where specific manufacturing processes could result in such surfaces. Even if the initial surfaces exhibit symmetric roughness, the running-in and sliding processes could result in asymmetric roughness distributions. In this paper, the effect of asymmetric asperity height distribution on the static friction coefficient is investigated theoretically and experimentally. The asymmetry of the surface roughness is modeled using the Pearson system of frequency curves. Two elastic-plastic static friction models, the Kogut-Etsion (KE) and Cohen-Kligerman-Etsion (CKE) models are adapted to account for asymmetric roughness and employed to obtain the tangential and normal contact forces. Static friction experiments using CV joint roller and housing surfaces, which exhibit different levels of surface roughness, were performed and directly compared with the KE and CKE static friction models using both a symmetric Gaussian as well as Pearson distributions of asperity heights. It is found that the KE model with the Pearson distribution compares favorably with the experimental measurements.
Wear, Jan 1, 2011
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Journal of Applied Mechanics, Jan 1, 2011
The effect of roughness on the frictional energy dissipation in fretting contact of nominally fla... more The effect of roughness on the frictional energy dissipation in fretting contact of nominally flat rough surfaces is studied. The contact is modeled as the statistical sum of asperity tip junctions. A mathematical analysis with a probability distribution of asperity heights in the form of a delta sequence is conducted to analytically show that a rougher surface dissipates more energy than a smoother surface. Numerical simulations with three typical measured surface roughness profiles are presented, validating the analytical finding that rougher surfaces dissipate more energy than smoother surfaces in fretting contact. The proposed statistical approach is compared with so called "direct" calculation methods, which analytically model discrete asperity contacts, and the differences regarding the energy dissipation in fretting are discussed.
International Journal of Solids …, Jan 1, 2011
A physics-based modeling approach for fretting behavior of nominally flat rough contact is propos... more A physics-based modeling approach for fretting behavior of nominally flat rough contact is proposed. This approach employs physics-based models for partial slip of spherical contacts to formulate the contact forces at asperity tips. The individual asperity forces are added by a statistical method to obtain the fretting response of a flat rough contact. This approach suggests the plasticity index as an important parameter for studying the surface roughness effects on fretting. Fretting responses obtained by one of the models favorably compare with experimental results obtained from bolted steel lap joints. Tangential stiffness and energy loss per cycle obtained from the experiments and the model predictions deviate at higher preloads. This discrepancy is due to limitations of the modeling approach in accounting for plastic response to tangential loading.
International Journal of Solids …, Jan 1, 2010
A physics-based modeling approach for partial slip behavior of a spherical contact is proposed. I... more A physics-based modeling approach for partial slip behavior of a spherical contact is proposed. In this approach, elastic and elastic-plastic normal preload and preload-dependent friction coefficient models are integrated into the Cattaneo-Mindlin partial slip solution. Partial slip responses to cyclic tangential loading (fretting loops) obtained by this approach are favorably compared with experiments and finite element results from the literature. In addition to load-deformation curves, tangential stiffness of the contact and energy dissipation per fretting cycle predictions of the models are also provided. Finally, the critical assumptions of elastically similar bodies, smooth contact surface and negligible adhesion, and limitations of this physics-based modeling approach are discussed.
Experimental Mechanics
An experimental apparatus designed specifically for fretting experiments on mechanical lap joints... more An experimental apparatus designed specifically for fretting experiments on mechanical lap joints is presented. A piezoactuator is used to impose fretting motion, and a tri-axial load cell is used to measure tangential force as well as possible misalignment forces. A laser nanosensor is employed to measure the relative motion between the joint halves. No post-processing and filtering of the data is needed to obtain the fretting response using this apparatus. Instead, raw data obtained from experiments with monolithic and 1-bolt aluminum and steel joints under various loading conditions suggest that noise, misalignment, stiffness and damping associated with the apparatus are minimal, and thus the fretting behavior of the mechanical lap joints is accurately captured. Analyses of typical fretting loops obtained by the proposed apparatus suggest that normal preload and maximum tangential displacement influence the critical joint parameters of stiffness and damping. Aluminum joints show a more compliant behavior with more energy dissipation compared to steel joints.
A model is presented that accounts for contact with a molecularly thin lubricant layer confined b... more A model is presented that accounts for contact with a molecularly thin lubricant layer confined between a rigid sphere and flat substrate. The sphere is moving at a high lateral velocity inducing high shear rates and a significant increase of lubricant viscosity. Interfacial slip is modeled based on experimental and molecular dynamics data and includes effects of lubricant morphology and chemistry. The model is used to interpret experimental measurements of viscosity and slip and express them as functions of shear rate. These ...
Nanotechnology, Jan 1, 2005
Abstract Breakdown voltage is a unique well-known indicator for gases. Previous work indicate t... more Abstract Breakdown voltage is a unique well-known indicator for gases. Previous work indicate that miniaturized gas ionization sensors, which are made up of two electrodes one of which accommodates vertically aligned carbon nanotubes (CNTs), reduce breakdown voltage thanks to electric ...
Journal of biomechanical engineering, Jan 1, 2009
In this paper, dynamical systems analysis and optimization tools are used to investigate the loca... more In this paper, dynamical systems analysis and optimization tools are used to investigate the local dynamic stability of periodic task-related motions of simple models of the lower-body musculoskeletal apparatus and to seek parameter values guaranteeing their stability. Several muscle models incorporating various active and passive elements are included and the notion of self-stabilization of the rigid-body dynamics through the imposition of musclelike actuation is investigated. It is found that self-stabilization depends both on muscle architecture and configuration as well as the properties of the reference motion. Additionally, antagonistic muscles (flexor-extensor muscle couples) are shown to enable stable motions over larger ranges in parameter space and that even the simplest neuronal feedback mechanism can stabilize the repetitive motions. The work provides a review of the necessary concepts of stability and a commentary on existing incorrect results that have appeared in literature on muscle self-stabilization.
Tribology Letters
Under the effects of high shear rate and confinement between solid surfaces, the behavior of a th... more Under the effects of high shear rate and confinement between solid surfaces, the behavior of a thin lubricant film deviates from that of the bulk, resulting in significant increases of lubricant viscosity and interfacial slip. A semi-empirical model accounting for the breakdown of continuum theory at the nanoscale is proposed-based on film morphology and chemistry from available experimental and molecular dynamics simulation data-to describe lubricant behavior under shear. Viscosity stiffening and interfacial slip models are introduced into the formulations of the normal (bearing) and shear forces acting on a sphere that moves within a thin lubricant film parallel to a rigid plane. The experimentally measured 'apparent' viscosity confounding the effects of both stiffening and slip is used to predict the hydrodynamic forces acting on a fully or partially submerged sphere for the purposes of describing lubricant contact in magnetic storage. The proposed sphere-on-flat model forms the basis of a future, dynamic contact with friction model that will account for lubricant contact in the context of molecularly thin lubricated rough surface contact.
[
Journal of Tribology, Jan 1, 2010
Journal of Tribology, Jan 1, 2010
Asymmetric height distribution in surface roughness is important in many engineering surfaces, su... more Asymmetric height distribution in surface roughness is important in many engineering surfaces, such as in constant velocity (CV) joints, where specific manufacturing processes could result in such surfaces. Even if the initial surfaces exhibit symmetric roughness, the running-in and sliding processes could result in asymmetric roughness distributions. In this paper, the effect of asymmetric asperity height distribution on the static friction coefficient is investigated theoretically and experimentally. The asymmetry of the surface roughness is modeled using the Pearson system of frequency curves. Two elastic-plastic static friction models, the Kogut-Etsion (KE) and Cohen-Kligerman-Etsion (CKE) models are adapted to account for asymmetric roughness and employed to obtain the tangential and normal contact forces. Static friction experiments using CV joint roller and housing surfaces, which exhibit different levels of surface roughness, were performed and directly compared with the KE and CKE static friction models using both a symmetric Gaussian as well as Pearson distributions of asperity heights. It is found that the KE model with the Pearson distribution compares favorably with the experimental measurements.
Wear, Jan 1, 2011
The user has requested enhancement of the downloaded file. All in-text references underlined in b... more The user has requested enhancement of the downloaded file. All in-text references underlined in blue are added to the original document and are linked to publications on ResearchGate, letting you access and read them immediately. This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues.
Journal of Applied Mechanics, Jan 1, 2011
The effect of roughness on the frictional energy dissipation in fretting contact of nominally fla... more The effect of roughness on the frictional energy dissipation in fretting contact of nominally flat rough surfaces is studied. The contact is modeled as the statistical sum of asperity tip junctions. A mathematical analysis with a probability distribution of asperity heights in the form of a delta sequence is conducted to analytically show that a rougher surface dissipates more energy than a smoother surface. Numerical simulations with three typical measured surface roughness profiles are presented, validating the analytical finding that rougher surfaces dissipate more energy than smoother surfaces in fretting contact. The proposed statistical approach is compared with so called "direct" calculation methods, which analytically model discrete asperity contacts, and the differences regarding the energy dissipation in fretting are discussed.
International Journal of Solids …, Jan 1, 2011
A physics-based modeling approach for fretting behavior of nominally flat rough contact is propos... more A physics-based modeling approach for fretting behavior of nominally flat rough contact is proposed. This approach employs physics-based models for partial slip of spherical contacts to formulate the contact forces at asperity tips. The individual asperity forces are added by a statistical method to obtain the fretting response of a flat rough contact. This approach suggests the plasticity index as an important parameter for studying the surface roughness effects on fretting. Fretting responses obtained by one of the models favorably compare with experimental results obtained from bolted steel lap joints. Tangential stiffness and energy loss per cycle obtained from the experiments and the model predictions deviate at higher preloads. This discrepancy is due to limitations of the modeling approach in accounting for plastic response to tangential loading.
International Journal of Solids …, Jan 1, 2010
A physics-based modeling approach for partial slip behavior of a spherical contact is proposed. I... more A physics-based modeling approach for partial slip behavior of a spherical contact is proposed. In this approach, elastic and elastic-plastic normal preload and preload-dependent friction coefficient models are integrated into the Cattaneo-Mindlin partial slip solution. Partial slip responses to cyclic tangential loading (fretting loops) obtained by this approach are favorably compared with experiments and finite element results from the literature. In addition to load-deformation curves, tangential stiffness of the contact and energy dissipation per fretting cycle predictions of the models are also provided. Finally, the critical assumptions of elastically similar bodies, smooth contact surface and negligible adhesion, and limitations of this physics-based modeling approach are discussed.
Experimental Mechanics
An experimental apparatus designed specifically for fretting experiments on mechanical lap joints... more An experimental apparatus designed specifically for fretting experiments on mechanical lap joints is presented. A piezoactuator is used to impose fretting motion, and a tri-axial load cell is used to measure tangential force as well as possible misalignment forces. A laser nanosensor is employed to measure the relative motion between the joint halves. No post-processing and filtering of the data is needed to obtain the fretting response using this apparatus. Instead, raw data obtained from experiments with monolithic and 1-bolt aluminum and steel joints under various loading conditions suggest that noise, misalignment, stiffness and damping associated with the apparatus are minimal, and thus the fretting behavior of the mechanical lap joints is accurately captured. Analyses of typical fretting loops obtained by the proposed apparatus suggest that normal preload and maximum tangential displacement influence the critical joint parameters of stiffness and damping. Aluminum joints show a more compliant behavior with more energy dissipation compared to steel joints.