  An interesting recent paper by Menga, Carbone & Dini (MCD, 2018, [1]),
suggests that in sliding adhesive contacts, the contact area should increase
due to tangential shear stresses at the interface, assumed to be constant and
corresponding to a material constant. This is not observed in the known
experiments, and is in sharp contrast with all the classical theories about the
transition from stick to sliding, both in the JKR (Griffith like) conditions
which involve singular pressure and shear, as well as in full general cohesive
models. We offer a rigorous thermodynamics calculation, which suggests in fact
there is no qualitative contrast but a very close quantitative agreement, with
previous theories. Actually, the model predicts an even stronger reduction of
contact area than predicted by Savkoor and Briggs, contrary to experimental
observations, so would certainly require some adjustements to consider
dissipative effects.
