friction

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

Submitted by Mike Ciavarella on Wed, 11/21/2018 - 15:30

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

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

Submitted by Mike Ciavarella on Fri, 02/02/2018 - 19:07

research

adhesion

friction

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

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

Submitted by Ahmed Elbanna on Mon, 10/23/2017 - 05:06

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

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

Submitted by Antonio Papangelo on Fri, 03/17/2017 - 09:49

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.

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

Submitted by Ahmed Elbanna on Sun, 03/12/2017 - 02:11

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.

Snaking bifurcations in a self-excited oscillator chain with cyclic symmetry

Submitted by Mike Ciavarella on Tue, 01/10/2017 - 06:03

subcritical Hopf bifurcation

Who is interested in non-linear dynamics of friction may find this nice.

Communications in Nonlinear Science and Numerical Simulation

Volume 44, March 2017, Pages 108–119

Extrusion, slide, and rupture of an elastomeric seal

Submitted by Zhengjin WANG on Sun, 12/11/2016 - 18:36

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 vi

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

Submitted by Ahmed Elbanna on Thu, 04/28/2016 - 15:20

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/)

Ahmed Elbanna (University of Illinois Urbana Champaign) and K. Ravi-Chandar (University of Texas at Austin)

Principal Scientist, Surfaces position available in Atlanta, GA

Submitted by ccodioso on Wed, 07/08/2015 - 15:46

Novelis is hiring for a Principal Scientist in Atlanta, GA.

Dynamic instabilities of frictional sliding at a bimaterial interface

Submitted by Eran Bouchbinder on Fri, 07/03/2015 - 06:37

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.

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