# Stick-Slip transition in dry friction - PhD thesis -part I

This is the "part I" of my PhD thesis.

It addresses the problem of the stick-slip transition at an interface experiencing dry friction taking inspiration from the experiments led by Prof. Fineberg, where for the first time, an high speed camera has been used to visualize how the contact interface evolves when stick-slip transition occurs.

The underlying idea was to provide analytical models that, in some extent, can interpreter some of the numerous experimental evidences that came from the direct observation of the sliding phenomena. In the chapters 1-2 a brief introduction of the equations that govern the contact of elastic bodies and the experimental test rig used in the Fineberg's experiments is presented. In chapter 3 the partial slip problem of a flat square-ended punch pressed against an half-plane and tangentially loaded above the contact interface is studied, then a FEM of the Prof. Fineberg experimental test rig will be proposed to avoid the hypothesis of half-plane elasticity, with good agreement between numerical and experimental results. In chapter 4 the implications of using a slip weakening friction law instead of the classical Coulomb law are discussed and an energetic criterion for slip inception is derived, which we will call "Griffith friction model". In chapter 5, using this "Griffith friction", the partial slip problem for different plane geometries (power law punches and sinusoidal profile) is solved.

The most of the data reported have been published in known international journal papers. A comprehensive list can be found here:

https://www.researchgate.net/profile/Antonio_Papangelo

Interactions and possible collaborations are welcome,

Antonio

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### Fineberg's experiments simulations with FEM are unpublished

I just wanted to remark that FEM simulations of Fineberg's experiments are largely unpublished, partly because we found that most of the main results were already found by Taloni et al. 2015, and partly for lack of time.

If anyone wants to try Fineberg's experiments with FEM, I am sure Antonio can share his code, I think it was ANSYS file.

Taloni, Alessandro, Andrea Benassi, Stefan Sandfeld, and Stefano Zapperi. "Scalar model for frictional precursors dynamics." Scientific reports 5 (2015).