arXiv subjects

Hector Alarcon

Publications and source records attributed to Hector Alarcon.

3 recordsLinked to original sources

arXiv2020

Nonlinear amplification of adhesion forces in interleaved books

Two interleaved phonebooks are nearly impossible to separate by pulling their spines. The very slight force exerted by the outer sheets of the assembly is amplified as the exponential of the square of the number of sheets, leading to a highly-resistant system even with a small number of sheets. We present a systematic and detailed study of the influences of the normal external force and the geometrical parameters of the booklets on the assembly strength. We conclude that the paper-paper adhesion force between the two outer sheets, on the order of a few mN, is the one that is amplified by the two interleaved system. The two-phonebooks experiment that has attracted the attention of students and non-scientific public all around the world as an outstanding demonstration of the strength of friction appears to be as well a spectacular macroscopic manifestation of the microscopic friction-adhesion coupling.

cond-mat.soft↗

arXiv2015

Self-amplification of solid friction in interleaved assemblies

It is nearly impossible to separate two interleaved phonebooks when held by their spines. A full understanding of this astonishing demonstration of solid friction in complex assemblies has remained elusive. In this Letter, we report on experiments with controlled booklets and show that the force required increases sharply with the number of sheets. A model captures the effect of the number of sheets, their thickness and the overlapping distance. Furthermore, the data collapse onto a self-similar master curve with one dimensionless amplification parameter. In addition to solving a long-standing familiar enigma, this model system provides a framework with which one can accurately measure friction forces and coefficients at low loads, and that has relevance to complex assemblies from the macro to the nanoscale.

physics.class-ph↗

arXiv2010

Softening induced instability of a stretched cohesive granular layer

We report on a cellular pattern which spontaneously forms at the surface of a thin layer of a cohesive granular material submitted to in-plane stretching. We present a simple model in which the mechanism responsible of the instability is the ``strain softening'' exhibited by humid granular materials above a typical strain. Our analysis indicates that such type of instability should be observed in any system presenting a negative stress sensitivity to strain perturbations.

physics.class-ph↗