Rate and State Friction

 

Introduction

At a macroscopic scale, propagation of slip front along frictional interfaces is studied for several
decades through the lenses of mode-II Linear Elastic Fracture Mechanics (LEFM). This theoretical framework is nowadays well-established to describe the failure of macroscopically homogeneous materials. However, at smaller scale, surfaces are rough and come into contact only through a small fraction of the total surface area, at the highest asperities (see as example cms/lang/en/pid/131883). The shear resistance associated with local surface pressure is then heterogeneously distributed along the slip plane. At the bridge between tribology and fracture mechanics, we study the dynamic rupture of heterogeneous slip plane with the motivation to relate small-scale properties of surfaces to their macroscopic behavior. 

Current Research

The dynamic rupture in presence of heterogeneities is characterized by small time and length scales and requires thereby a very fine numerical discretization along the slip plane. We are simulating rupture event using a spectral formulation of the elasto-dynamic boundary integral equation which provides a level of detail at the slip plane unattainable with more conventional methods (such as the finite element and finite difference schemes).

We are currently studying the distortion observed along a dynamic front meeting a tougher inclusion in the slip plane. We are also aiming at quantifying/predicting the energy radiated as far-field waves during these heterogeneous events.

Dynamic slip front meeting a 5-time tougher inclusion along the rupture plane. 

 

The roughening of dynamic slip front moving along a disordered plane is another part of our current research topic. Our general target is to bring new insight to the onset of slip between two mesoscopically rough surfaces in contact where the resistance to sliding is heterogeneously distributed.

Shear strength [MPa] highlighting the progressive roughening of a slip front meeting an inhomogeneous fractal distribution of toughness.

[1]
F. Barras; D. S. Kammer; P. H. Geubelle; J.-F. Molinari : A study of frictional contact in dynamic fracture along bimaterial interfaces; International Journal of Fracture. 2014. DOI : 10.1007/s10704-014-9967-z.
[2]
D. S. Kammer; V. Yastrebov; G. Anciaux; J.-F. Molinari : The existence of a critical length scale in regularised friction; Journal of the Mechanics and Physics of Solids. 2014. DOI : 10.1016/j.jmps.2013.10.007.