A Mesoscopic Friction Model Based on Surface Roughness and its Statistical Description

2011 ◽  
Author(s):  
Bernhard Stingl ◽  
Norbert P. Hoffmann
Keyword(s):  
Surface Roughness ◽  
Frictional Resistance ◽  
Friction Model ◽  
Dynamic Processes ◽  
Engineering Practice ◽  
Rough Interface ◽  
Physical Processes ◽  
Macroscopic Scale ◽  
Separation Of Scales ◽  
Frictional Behaviour

In engineering practice frictional resistance is considered on a macroscopic scale: All the physical processes resulting in resistance against sliding are subsumed under a single friction coefficient, though there is no real evidence for this separation of scales. A feasible way to bring multiscale modelling to frictional problems can be the consideration of friction on a mesoscale on which the roughness of apparently smooth surfaces appears. Although surface roughness has always been connected with friction, recently experiments and models revealed that dynamic processes in the rough interface determine the frictional behaviour.

Friction Force and Stresses Analysis for Contact of Assembled Details

2006 ◽  
Vol 113 ◽  
pp. 334-338
Author(s):  
Z. Dreija ◽  
O. Liniņš ◽  
Fr. Sudnieks ◽  
N. Mozga
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Plastic Deformation ◽  
Friction Force ◽  
Sliding Friction ◽  
Friction Model ◽  
Contact Interface ◽  
Finite Element Program ◽  
Elastic Plastic ◽  
Element Program

The present work deals with the computation of surface stresses and deformation in the presence of friction. The evaluation of the elastic-plastic contact is analyzed revealing three distinct stages that range from fully elastic through elastic-plastic to fully plastic contact interface. Several factors of sliding friction model are discussed: surface roughness, mechanical properties and contact load and areas that have strong effect on the friction force. The critical interference that marks the transition from elastic to elastic- plastic and plastic deformation is found out and its connection with plasticity index. A finite element program for determination contact analysis of the assembled details and due to details of deformation that arose a normal and tangencial stress is used.

scholarly journals Learning dominant physical processes with data-driven balance models

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jared L. Callaham ◽  
James V. Koch ◽  
Bingni W. Brunton ◽  
J. Nathan Kutz ◽  
Steven L. Brunton
Keyword(s):  
Nonlinear Optics ◽  
Unsupervised Learning ◽  
History Of Science ◽  
Traditional Approach ◽  
Data Driven ◽  
Mechanistic Models ◽  
Physical Processes ◽  
History Of ◽  
Separation Of Scales ◽  
Geophysical Fluids

AbstractThroughout the history of science, physics-based modeling has relied on judiciously approximating observed dynamics as a balance between a few dominant processes. However, this traditional approach is mathematically cumbersome and only applies in asymptotic regimes where there is a strict separation of scales in the physics. Here, we automate and generalize this approach to non-asymptotic regimes by introducing the idea of an equation space, in which different local balances appear as distinct subspace clusters. Unsupervised learning can then automatically identify regions where groups of terms may be neglected. We show that our data-driven balance models successfully delineate dominant balance physics in a much richer class of systems. In particular, this approach uncovers key mechanistic models in turbulence, combustion, nonlinear optics, geophysical fluids, and neuroscience.

scholarly journals The description of friction of silicon MEMS with surface roughness: virtues and limitations of a stochastic Prandtl–Tomlinson model and the simulation of vibration-induced friction reduction

2010 ◽  
Vol 1 ◽  
pp. 163-171 ◽  
Author(s):  
W Merlijn van Spengen ◽  
Viviane Turq ◽  
Joost W M Frenken
Keyword(s):  
Surface Roughness ◽  
Critical Role ◽  
Measurement Data ◽  
Friction Model ◽  
Friction Reduction ◽  
Atomic Scale ◽  
Mems Devices ◽  
Tomlinson Model ◽  
Atomic Force ◽  
On Chip

We have replaced the periodic Prandtl–Tomlinson model with an atomic-scale friction model with a random roughness term describing the surface roughness of micro-electromechanical systems (MEMS) devices with sliding surfaces. This new model is shown to exhibit the same features as previously reported experimental MEMS friction loop data. The correlation function of the surface roughness is shown to play a critical role in the modelling. It is experimentally obtained by probing the sidewall surfaces of a MEMS device flipped upright in on-chip hinges with an AFM (atomic force microscope). The addition of a modulation term to the model allows us to also simulate the effect of vibration-induced friction reduction (normal-force modulation), as a function of both vibration amplitude and frequency. The results obtained agree very well with measurement data reported previously.

Analysis of Ultralong Friction Pile Based on Gradient Dependent Nonlocal Friction Model

2014 ◽  
Vol 638-640 ◽  
pp. 380-383
Author(s):  
Xiao Yan Luo ◽  
Wei Ping Liu
Keyword(s):  
Frictional Resistance ◽  
Friction Model ◽  
Gradient Theory ◽  
Friction Mechanism ◽  
New Model ◽  
Friction Law ◽  
Nonlocal Friction ◽  
Set Up ◽  
Friction Pile ◽  
Geotechnical Problems

Based on the gradient theory, the gradient dependent nonlocal friction model is established. It is a new model which can describe the nonlocal friction effect. Based on Mindlin’s solution of displacement, an elastic solution of the lateral frictional resistance for ultralong friction pile is derived. The ultralong friction pile is analyzed by using the gradient dependent nonlocal friction model. Compared with the solution to the local friction law, the results shows that nonlocal friction law is feasible and reliable. The study is helpful for understanding the friction mechanism in geotechnical problems. It is a good attempt to set up the more actual and more accurate friction model.

Scaling Analysis of a- and poly-Si Surface Roughness by Atomic Force Microscopy

1994 ◽  
Vol 367 ◽  
Author(s):  
T. Yoshinobu ◽  
A. Iwamoto ◽  
K. Sudoh ◽  
H. Iwasaki
Keyword(s):  
Surface Roughness ◽  
Atomic Force Microscopy ◽  
Surface Area ◽  
Scaling Behavior ◽  
Linear Size ◽  
Scaling Analysis ◽  
Macroscopic Scale ◽  
Force Microscopy ◽  
Atomic Force ◽  
Roughness Exponent

AbstractThe scaling behavior of the surface roughness of a-and poly-Si deposited on Si was investigated by atomic force microscopy (AFM). The interface width W(L), defined as the rms roughness as a function of the linear size of the surface area, was calculated from various sizes of AFM images. W(L) increased as a power of L with the roughness exponent ∝ on shorter length scales, and saturated at a constant value of on a macroscopic scale. The value of roughness exponent a was 0.48 and 0.90 for a-and poly-Si, respectively, and σ was 1.5 and 13.6nm for 350nm-thick a-Si and 500nm-thick poly-Si, respectively. The AFM images were compared with the surfaces generated by simulation.

On the Acceleration Limits for Sliding and Detachment Between Contacting Rough Surfaces for Micropart Manipulation in a Dry Environment

2013 ◽  
Vol 1 (1) ◽  
Author(s):  
Mohsin Rizwan ◽  
Panos S. Shiakolas
Keyword(s):  
Surface Roughness ◽  
Research Area ◽  
Friction Model ◽  
Automated System ◽  
Model Parameters ◽  
Critical Acceleration ◽  
Acceleration Threshold ◽  
Material Hardness ◽  
Active Research ◽  
Active Research Area

Micropart manipulation is an active research area encompassing a wide array of fields and applications. As the size of the parts to be manipulated by an automated system decreases, the dominant forces are different compared to macroscale ones. Thus, for accurately modeling and evaluating the motion dynamics of a micropart, microscale forces and their effects must be considered. This manuscript employs a nanomicroscale friction model based on the Kogut–Etsion model that along with microscale forces considers surface roughness and material hardness properties to identify the acceleration threshold that would cause a micropart to start sliding on a carrier surface or vertically detach from the carrier surface during gripperless manipulation in a dry environment. The microscale forces change significantly as a function of the surface roughness of the two contacting surfaces. The results indicate that there will always be critical acceleration values below which no sliding or detachment takes place. Also, for the same model parameters, the sliding acceleration is smaller than the detachment acceleration for softer materials and larger for harder materials. The sliding acceleration threshold is more sensitive to hardness changes at smaller surface roughness values as compared to larger surface roughness values. The material hardness has no effect on the detachment acceleration for the same surface roughness values. The knowledge of the acceleration thresholds and their relative magnitudes could be advantageously employed for the development of gripperless manipulation approaches for microcomponent or microdevice handling or for the development of microconveyor platforms for controlled micropart translocation.

scholarly journals Surface roughness of three types of modern plastic bracket slot floors and frictional resistance

2013 ◽  
Vol 84 (1) ◽  
pp. 177-183 ◽  
Author(s):  
Sung-Hwan Choi ◽  
Da-Young Kang ◽  
Chung–Ju Hwang
Keyword(s):  
Surface Roughness ◽  
Stainless Steel ◽  
Three Dimensional ◽  
Frictional Resistance ◽  
Lower Surface ◽  
Reinforced Plastic ◽  
Ceramic Brackets ◽  
Sliding Test ◽  
Plastic Brackets

ABSTRACT Objective: To quantitatively analyze the surface roughness of the slot floors of three types of modern plastic brackets and to measure static frictional force during sliding mechanics in vitro. Materials and Methods: Control groups comprised stainless steel brackets and monocrystalline ceramic brackets. Test groups comprised three types of 0.022-in slot, Roth prescription, plastic, maxillary right central incisor brackets. Test groups included glass fiber-reinforced polycarbonate, filler-reinforced polycarbonate, and hybrid polymer with inserted metal slot brackets. The static frictional resistance caused by sliding movements with an archwire (stainless steel) in vitro was quantitatively analyzed. Both scanning electron microscope and three-dimensional optical surface profiling were used. Results: Scanning electron microscope and three-dimensional optical surface profiler revealed that all as-received brackets had irregular slot floor surfaces, and both irregularity and roughness increased after the archwire sliding test. The ceramic brackets in the control group showed significantly lower surface roughness values and higher frictional values during the archwire sliding test compared with the other brackets. The glass or filler-reinforced plastic brackets exhibited significantly higher static frictional values than the metallic slot type brackets (P < .001). The hybrid polymer with inserted metal slot brackets showed relatively lower surface roughness and frictional values compared with the stainless steel control bracket. Conclusion: Glass or filler-reinforced plastic brackets showed higher frictional resistance than metallic slot–type brackets. A plastic bracket with inserted metal slot may be the best choice among plastic brackets for low frictional resistance and to avoid damage from sliding movements of the archwire.

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