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friction

Mike Ciavarella's picture

apparent paradox: for a sliding flat punch on a viscoelastic halfspace, friction is zero or not?

dear Imechanica friends here is an apparent paradox: for a sliding flat punch on a viscoelastic halfspace, friction is zero or not?  Certainly there seems to be viscoelastic dissipation, but the pressure is also normal to dispacements, so am I missing something obvious here?

ndaphalapurkar's picture

Postdoc opening--Modeling Shock Compaction of Granular Materials

Colleagues,

The Solid Mechanics--Damage and Failure team at Los Alamos National Laboratory is seeking a highly motivated and productive postdoc candidate in the area of shock compaction, with a focus on simulating the microstructure evolution of granular materials using explicit representation of microstructures.

Job ad here

carpick's picture

Postdoctoral Position: Oxide Nanoparticles as Lubricant Additives

THE SCHOOL OF ENGINEERING AND APPLIED SCIENCE at the UNIVERSITY OF PENNSYLVANIA invites applications for a full-time position as a Postdoctoral Researcher in the DEPARTMENT OF MECHANICAL ENGINEERING AND APPLIED MECHANICS in the laboratory of Prof. Robert W. Carpick (http://carpick.seas.upenn.edu).

hyunwoo's picture

Multifunctional “Hydrogel Skins” on Diverse Polymers with Arbitrary Shapes

In this paper, we introduce a new simple yet effective strategy to form "hydrogel skins" on polymer-based medical devices with arbitrary shapes. Hydrogel skins can convert any surface of polymer devices into robust, wet, soft, slippery, antifouling, and ionically conductive without affecting the original properties and geometries.

Abstract

Mike Ciavarella's picture

Is Tribology Approaching Its Golden Age? Grand Challenges in Engineering Education and Tribological Research

An interesting paper by VL Popov which suggests many problems of tribology are still very far from being remotely solved.  Despite the very detailed theories for example on rough contact using fractal surfaces on which we have debated mainly academically , there is not a single theory for any quantitative prediction of friction coefficient which can vary by 1 order of magnitude and its dependence on many variables, let alone wear coefficient which can vary up to 7 orders of magnitude.  What is left to do, other than measure?   Is tribology bound to be in practice just an experimental area? 

Mike Ciavarella's picture

A recent PNAS paper explained! FRACTURE MECHANICS SIMPLE CALCULATIONS TO EXPLAIN SMALL REDUCTION OF THE REAL CONTACT AREA UNDER SHEAR

If you have seen the very nice PNAS paper which just appeared

Sahli, R., Pallares, G., Ducottet, C., Ben Ali, I.E., Al Akhrass, S., Guibert, M., Scheibert, J., 2018, Evolution of real contact area under shear, Proceedings of the National Academy of Sciences, 115(3), pp. 471-476.

Here we provide a simple explanation.

FACTA UNIVERSITATIS

Series: Mechanical Engineering

DOI: 10.22190/FUME180108007C

Short Communication

FRACTURE MECHANICS SIMPLE CALCULATIONS TO EXPLAIN SMALL REDUCTION OF THE REAL CONTACT AREA UNDER SHEAR

UDC 539.6

Ahmed Elbanna's picture

USNC-TAM: Minisymposium on Friction, Fracture, and Damage

Dear Colleagues,

We cordially invite you to submit an abstract to MS 335: Friction, Fracture, and Damage; a minisymposium that will take place as part of the upcoming US National Congress on Theoretical and Applied Mechanics (Chicago, IL June 4th -9 th 2018). Abstract Deadline: Nov 10th :http://sites.northwestern.edu/usnctam2018/

Ahmed Elbanna, University of Illinois Urbana Champaign

Krishnaswamy Ravi-Chandar, University of Texas at Austin

Antonio Papangelo's picture

Cyclic response of friction damped mechanical systems - PhD thesis - part II

This is the "part II" of my PhD thesis.

It addresses the problem of finding the dynamic cyclic response of mechanical systems experiencing dry friction with a particular focus on the influence of varying normal and tangential loads. I first start from a single degree of freedom model and gradually increase the complexity of the system. In the last chapter I address a system with 12 degrees of freedom which shows localized vibration states, that are very similar to solutions known in other physics fields like optics and fluid dynamics. 

Ahmed Elbanna's picture

Localization and instability in sheared granular materials: Role of friction and vibration

Shear banding and stick-slip instabilities have been long observed in sheared granular materials. Yet, their microscopic underpinnings, interdependencies and variability under different loading conditions have not been fully explored. Here, we use a non-equilibrium thermodynamics model, the Shear Transformation Zone theory, to investigate the dynamics of strain localization and its connection to stability of sliding in sheared, dry, granular materials. We consider frictional and frictionless grains as well as presence and absence of acoustic vibrations.

Extrusion, slide, and rupture of an elastomeric seal

Elastomeric seals are essential to two great technological advances in oilfields:  horizontal drilling and hydraulic fracturing.  This paper describes a method to study elastomeric seals by using the pressure-extrusion curve (i.e., the relation between the drop of pressure across a seal and the volume of extrusion of the elastomer).  Emphasis is placed on a common mode of failure found in oilfields:  leak caused by a crack across the length of a long seal.  We obtain an analytical solution of large elastic deformation, which is analogous to the Poiseuille flow of viscous liquids.

Ahmed Elbanna's picture

[Call for Abstracts] SES minisymposium on Friction, Fracture, and Damage

Dear Colleagues,

We would like to invite you to consider submitting abstracts to the following minisymposium taking place as part of the Soceity of Engineering Sciences meeting to be hosted by the University of Maryland (October 4-7, 2016)

D-9 :Friction, Fracture and damage (http://ses2016.org/symposium-d-9-friction-fracture-and-damage/)

Eran Bouchbinder's picture

Dynamic instabilities of frictional sliding at a bimaterial interface

Understanding the dynamic stability of bodies in frictional contact steadily sliding one over the other is of basic interest in various disciplines such as physics, solid mechanics, materials science and geophysics. Here we report on a two-dimensional linear stability analysis of a deformable solid of a finite height H, steadily sliding on top of a rigid solid within a generic rate-and-state friction type constitutive framework, fully accounting for elastodynamic effects.

pastewka's picture

PhD Position in Computational Mechanics of Glasses, Karlsruhe Institute of Technology

Friction and wear are important processes that determine the function of many mechanical devices, but their underlying microscopic physical principles are complex and often not well understood. Amorphous – or glassy – materials often form on surfaces that have experienced frictional loading. The research will involve large-scale molecular dynamics simulation of the near-surface deformation upon indentation and scratching of network and bulk metallic glasses.

Mike Ciavarella's picture

rate-state dependent friction in ANSYS

Dear collegues

a quick question:- I am playing with continuum models of Contact (Hertz, Westergaard and so on) and friction laws. However, I prefer for my students to use ANSYS FEM code. In Ansys there is standard Coulomb, rate-dependence but not rate-state (unless one codes some user subroutines). See

https://www.sharcnet.ca/Software/Fluent14/help/ans_ctec/Hlp_ctec_realkey...

Ahmed Elbanna's picture

Call for Abstracts; EMI 2015 Stanford

Dear colleagues,

We cordially invite you to submit your contributions to the following minisymposium: Multiscale Modeling and Simulation of Fracture and Fragmentation Processes taking place as part of the Engineering Mechanics Institute conference (JUne 16-19, 2015) at Stanford.

Best Regards,

Ahmed Elbanna*, University of Illinois at Urbana Champaign, USA
Glaucio Paulino, University of Illinois at Urbana Champaign, USA

MS 54: Multiscale Modeling and Simulation of Fracture and Fragmentation Processes

Announcing Wear of Materials 2015 - Website has just gone live

20th International Conference on Wear of Materials
12-16 April 2015
The Sheraton Centre, Toronto, Canada

The 20th International Conference on Wear of Materials will focus on both the fundamental and applied aspects of wear and friction of materials at the macro-, micro-, and nano-scale. It will address the understanding of tribological phenomena; particularly the progress in recent decades and a special session will concentrate on modeling of wear.

Ahmed Elbanna's picture

MM&FGM14: 13th International Conference on Multiscale Modeling and Functionally Graded Materials

Dear Colleagues,

Please consider submitting an abstract to the 13th Internation conference on Multiscale Modeling and Functionally Graded Materials to be held on October 19-22, 2014; in  Taua Resort, SP, Brazi. More information about the conference could be found here:

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Ahmed Elbanna's picture

17 th National Congress on Theoretical and Applied Mechanics June 15-20 (Michigan State University)

Dear all,

I would like to bring to your attention the following minisymposium that is organized as part of the NCTAM 17 (Michigan State University, June 15-20, 2014)

http://www.usnctam2014.org/minisymposium/friction-adhesion-and-fracture-...

 

Friction, Adhesion and Fracture: From microscale physics to macroscale response

Frictional rolling contact model CONTACT version 13.1 released

Dear all,

Herewith I want to announce the release of the frictional rolling contact model CONTACT version 13.1.

The main changes with respect to earlier versions of the program are as follows:

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