JKR

Hello:  I would be interested in any comment about this preprint on fibrillar viscoelastic adhesion, originally devised by Schargott Popov and Gorb, where we use for the first time not only the Schapery model for nucleation of cracks, but also the Shrimali and Lopez Pamies, which leads to quite stronger enhancement of adhesion (the limit is the square of the Schapery one), and pull-off with no real prior propagation phase.  Propagation with Schapery nucleation criterion is found to be qualitatively similar to the Schapery and Persson-Brener propagation theories, except that the reference ve

dear Friends

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.

Jim Barber and I just got accepted this paper in JMPS, and it is also already available on Arxiv.  We found a remarkably simple closed form solution for adhesion on orthotropic materials in the planes of symmetry.  This shows adhesion can increase significantly due to anisotropy, namely the JKR solution continues to hold in the sense of mean elastic modulus, but the prefactor can grow without limit. We expect applications in crystals indentation, but also in locomotion in biological world.

Welcome to February 2010 Journal Club!  This month, I look forward to a lively discussion on the mechanics of structured and patterned interfaces in which geometry is used to tailor adhesion.  Much of the work in this area has been inspired by a variety of animals and insects that have feet covered with small structures (often hierarchical and sub-micrometer in size at the end) that allow them to strongly adhere to a broad range of surfaces.  The best known example is the Tokay Gecko (Gekko gecko), which can achieve an adhesion force much greater than its body weight and can quickl

Yesterday I had the distinct pleasure of seeing a mechanics seminar delivered "tag-team" by Ken Johnson and Jim Greenwood. (I know several people have thought I was a bit mad for jumping "across the pond" but there are really some amazing benefits of being part of the Cambridge Engineering faculty!)