Collision duration in the elastic regime

Abstract The concentrated contact formed between a steel ball and a glass disc—the optical elastohydrodynamic lubrication (EHD) rig—has been the primary instrument for experimental investigations of elastohydrodynamic film thickness. It has been a source for values of pressure-viscosity coefficient, a difficult-to-define property of liquids. However, comparisons with the pressure dependence of the viscosity obtained in viscometers show little agreement. There are multiple reasons for this failure including shear-thinning and compressibility of the oil. Another reason for the poor agreement is the subject of this short note. The optical EHD rig using glass as one surface will only be in the piezoviscous-elastic (EHD) regime when the pressure-viscosity coefficient is large. For low values, it would be operating in the isoviscous-elastic regime (soft EHD).

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A New Method for Elastic-Plastic Contact Analysis of a Deformable Sphere and a Rigid Flat

Journal of Tribology ◽

10.1115/1.2164469 ◽

2005 ◽

Vol 128 (2) ◽

pp. 221-229 ◽

Cited By ~ 32

Author(s):

Li Po Lin ◽

Jen Fin Lin

Keyword(s):

New Method ◽

Contact Load ◽

Rigid Sphere ◽

The Finite Element Method ◽

Numerical Errors ◽

Elastic Regime ◽

Contact Loads ◽

Indentation Tests ◽

Metal Materials ◽

Contact Parameters

A new method is developed in the present study to determine the elastoplastic regime of a spherical asperity in terms of the interference of two contact surfaces. This method provides an efficient way to solve the problem of discontinuities often present in the reported solutions for the contact load and area or the gradients of these parameters obtained at either the inception or the end of the elastoplastic regime. The well-established solutions for the elastic regime and experimental data of metal materials using indentation tests are provided as the references to determine the errors of these contact parameters due to the use of the finite-element method. These numerical errors provide the basis to adjust the contact area and contact load of a rigid sphere in contact with a flat such that the dimensionless mean contact pressure Pave∕Y (Y: the yielding strength) and the dimensionless contact load Fpc∕Fec (Fec, Fpc: the contact loads corresponding to the inceptions of the elastoplastic and fully plastic regimes, respectively) reaches the criteria arising at the inception of the fully plastic regime, which are available from the reports of the indentation tests for metal materials. These two criteria are however not suitable for the present case of a rigid flat in contact with a deformable sphere. In the case of a rigid flat in contact with a deformable sphere, the proportions in the adjustments of these contact parameters are given individually the same as those arising in the indentation case. The elastoplastic regime for each of these two contact mechanisms can thus be determined independently. By assuming that the proportion of adjustment in the elastoplastic regime is a linear function, the discontinuities appearing in these contact parameters are absent from the two ends of the elastoplastic regime in the present study. These results are presented and compared with the published results.

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Analysis of the Elasto-Plastic Response of a Polygonal Packing

Materials: Processing, Characterization and Modeling of Novel Nano-Engineered and Surface Engineered Materials ◽

10.1115/imece2002-32498 ◽

2002 ◽

Author(s):

Fernando Alonso Marroqui´n ◽

Hans Herrmann ◽

Stefan Luding

Keyword(s):

Poisson Ratio ◽

Young Modulus ◽

Dynamics Simulation ◽

Elastic Response ◽

Additional Parameter ◽

Plastic Response ◽

Plastic Deformations ◽

Elastic Regime ◽

Constitutive Response ◽

Flow Directions

We investigate the constitutive response of two-dimensional packed samples of polygons using molecular dynamics simulation. The incremental elasto-plastic response is examined in the pre-failure regime. Besides the Young modulus and the Poisson ratio, an additional parameter must be included, which takes into account the anisotropy of the elastic response. The plastic deformations are described by the introduction of the yield and the flow directions. These directions do not agree, which reproduces the non-associated feature of realistic soils. In order to detect the yield surface, different loading-unloading-reloading tests were performed. During the reload path, it is found that the yielding develops continuously with the amplitude of loading, which does not allow to identify a purely elastic regime.

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Effect of uniaxial loading on the structural anisotropy and the dynamics of atoms of Cu50Zr50 metallic glasses within the elastic regime studied by molecular dynamics simulation

Acta Materialia ◽

10.1016/j.actamat.2011.03.054 ◽

2011 ◽

Vol 59 (11) ◽

pp. 4303-4313 ◽

Cited By ~ 25

Author(s):

Y. Zhang ◽

N. Mattern ◽

J. Eckert

Keyword(s):

Molecular Dynamics ◽

Molecular Dynamics Simulation ◽

Metallic Glasses ◽

Uniaxial Loading ◽

Dynamics Simulation ◽

Structural Anisotropy ◽

Elastic Regime

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Plastic avalanches in the so-called elastic regime of metallic glasses

The European Physical Journal B ◽

10.1140/epjb/e2018-90051-7 ◽

2018 ◽

Vol 91 (6) ◽

Cited By ~ 7

Author(s):

Alexandra E. Lagogianni ◽

Chen Liu ◽

Kirsten Martens ◽

Konrad Samwer

Keyword(s):

Metallic Glasses ◽

Elastic Regime

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Friction of Microscale Contacts on Diamond-Like Carbon Nanocomposite Coatings

World Tribology Congress III, Volume 2 ◽

10.1115/wtc2005-64094 ◽

2005 ◽

Cited By ~ 3

Author(s):

Richard R. Chromik ◽

Kathryn J. Wahl

Keyword(s):

Shear Stress ◽

Contact Stress ◽

Interfacial Shear Stress ◽

Interfacial Shear ◽

Nanocomposite Coatings ◽

Diamond Like Carbon ◽

Friction Behavior ◽

Dlc Coatings ◽

Elastic Regime ◽

Carbon Nanocomposite

Microtribology of diamond-like carbon (DLC) nanocomposite coatings was studied using a commercially available nanoindentation system. Reciprocating sliding tests were conducted at 4 μm/s over track lengths of 8 μm with diamond and sapphire counterfaces with nominal diameters of 20 and 300 microns, respectively. Measured contact stresses were between 0.2 and 2.0 GPa for both tips. The friction behavior as a function of the contact stress was explored in the elastic regime. Measured interfacial shear stress for these sliding contacts were 12 ± 1 MPa for sapphire and 31 ± 3 MPa for diamond against DLC coatings.

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Schwarzites to schwarzynes: A new class of superdeformable materials

MRS Advances ◽

10.1557/adv.2020.298 ◽

2020 ◽

Vol 5 (37-38) ◽

pp. 1947-1954

Author(s):

Eliezer Fernando Oliveira ◽

Douglas Soares Galvao

Keyword(s):

Mechanical Properties ◽

Molecular Dynamics ◽

Force Field ◽

Molecular Dynamics Simulations ◽

Elastic Properties ◽

High Temperatures ◽

Preliminary Results ◽

New Class ◽

Elastic Regime ◽

Dynamics Simulations

AbstractIn this work, we have investigated the structural and mechanical properties of a new class of soft and superelastic materials, called schwarzynes. These materials are obtained by inserting sp carbon atoms (acetylenic groups) into the schwarzite framework. Using fully atomistic molecular dynamics simulations with the AIREBO force field, our results show that schwarzynes are stable materials up to high temperatures (1000K). Schwarzynes exhibit a very wide elastic regime, some of them up to 70% strain without structural fractures. Our preliminary results show that the elastic properties can be easily engineered by tuning the number of acetylenic groups and the crystallographic directions where they are inserted.

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