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Mike Ciavarella's blog

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On the application of fracture mechanics mixed-mode models of sliding with friction and adhesion

I attach a PREPRINT of a paper on the application of thermodynamics to mixed mode fracture mechanics models of contacts with friction and adhesion.  Comments welcome.   Regards, MC

 

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A comment on "A dimensionless measure for adhesion and effects of the range of adhesion in contacts of nominally flat surfaces" by M. H. Muser

I attach a Letter I sent to the Editor of a tribology journal, concerning adhesion of rough surfaces. 

I contend that some "criteria" that have been proposed based on extrapolation of numerical results are due to the limitations in present numerical sophisticated rough contact simulations, which only span at most 3 orders of magnitude of wavelengths, so typically people simulate from nanometer to micrometer scale.

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15 phd positions in MECHANICAL ENGINEERING at Politecnico di BARI

For infos about projects in contact mechanics, friction, wear, thermoelastic instabilities (for some ideas https://www.researchgate.net/profile/Michele_Ciavarella2), please contact me at mciava@poliba.it

Deadline for application Sept.6, 2019.

Details on admission at:

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review paper: The role of adhesion in contact mechanics

Journal of The Royal Society Interface 16(151), February 2019.    DOI: 10.1098/rsif.2018.0738

Michele Ciavarella Junki Joe Junki Joe Antonio Papangelo James Richard Barber

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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? 

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On stickiness criteria for multiscale random rough contacts

We have just submitted a paper which solves a problem that I have been struggling to solve for many years.

Any comments are welcome to improve, while the paper goes the standard review process in the journal we submitted it.

 

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are fractal surfaces adhesive? a new attempt on JMPS

In 2007 I wrote a question in Imechanica, IS THERE NO PULL-OFF FOR ADHESIVE FRACTAL SURFACES?

Clearly, in 2007 this question was too hard to answer.  I pointed there that Fuller and Tabor 1975 asperity theory predicted a weird limit for a true fractal surface, that of no stickiness for any fractal dimension or amplitude, in the limit.

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a new book "Contact Mechanics" from JR Barber

I am pleased to suggest a very interesting new book from prof JR Barber of UMich, a leading scientist in the field of contact mechanics.

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Knowing the strength of adhesion

Knowing the strength of adhesion

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National TV program on Politecnico di BARI and its successes

See a national broadcast on Politecnico di BARI and the region Puglia, with its successes, including the worldwide success of Diesel common rail technology, the GE centre on Addittive Manufacturing and Cold Spray, and others.

 

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a "contact sport" between academics

Recently, there was a big competition announced for rough elastic adhesive contact --- by Martin Muser as organizer.  This was published in Tribology Letter, involved the effort of many groups in the world, and finally got even a commentary in Science by Rob Carpick.

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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

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a quite critical comment of a recent set of fretting fatigue experiments

 

Effect of out-of-phase loading on fretting fatigue response of Al7075-T6 under cyclic normal loading using a new testing apparatu

Article reference: EFM5856
Journal title: Engineering Fracture Mechanics
Corresponding author: Prof. M. Ciavarella
First author: Prof. M. Ciavarella
Online publication complete: 1-FEB-2018
DOI information: 10.1016/j.engfracmech.2018.01.031

Dear Prof. Ciavarella,

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brake squeal

An interesting commercial/scientific paper 

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under certain extreme conditions, the Navier-Stokes equations output nonsense.

 

Two mathematicians prove that under certain extreme conditions, the Navier-Stokes equations output nonsense.

Here.

 

 

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Nobel laureate Randy Schekman: How journals like Nature, Cell and Science are damaging science

An article on the Guardian here.  Critics will say Shelkman has founded his own open access journal, here, probably competing with Nature, Cell and Science, which explains a lot.

 

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Kenneth Langstreth Johnson. 19 March 1925 — 21 September 2015

I strongly recommend reading these two papers about the recent loss of Ken L Johnson, FRS, Timoshenko Medallist, Gold Tribology Medal, who died the day of my 45th birthday, exactly twice as old.

Rod Smith Biographical Memoirs of Fellows of the Royal Society · August 2016 Kenneth Langstreth Johnson. 19 March 1925 — 21 September 2015 DOI: 10.1098/rsbm.2016.0012   

Hills, D. A., Nowell, D., & Barber, J. R. (2016). KL Johnson and contact mechanics. Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science, 0954406216634121.

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Certification for Damage Tolerance

I've posted a new forum.   Please see here.

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An inspiring seminar by Prof. Huajian Gao -- Mechanics as an Enabling tool in bioinspired materials and biological interactions of nanomaterials

Professor Huajian Gao of Brown University speaks at MIT Distinguished Seminar Series (March 2016).

It is a unique opportunity to enjoy the many important recent achievements of Huajian's group.

Mechanics as an Enabling tool in bioinspired materials and biological interactions of nanomaterials

Here.

Not to be missed!

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