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Modeling Slip Precursors at Frictional Interfaces

le 6 mars 2014
13H30

J.F. Molinari, Computational Solid Mechanics Laboratory, School of Architecture, Civil and Environmental Engineering (ENAC), School of Engineering (STI), Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne, Switzerland

J.F. Molinari.jpg

J.F. Molinari.jpg

Local slip instabilities, which involve rupture initiation and propagation along interfaces, are of fundamental importance to engineering and geosciences. The mechanics behind these local slip events is however highly complex and not well understood. Recent experimental observations [1] reveal that the propagation speed of the slip front varies along its path and is coupled to the static local shear to normal stress ratio. In order to reproduce these laboratory-earthquakes experiments, we simulate with the finite-element method the propagation of slip fronts at frictional interfaces between viscoelastic solids. The adopted friction law is based on the experimental Prakash-Clifton law [2] to smoothen the variation of the interface shear strength due to an instantaneous variation in the normal stress, and to avoid the ill-posedness of Coulomb friction law [3,4].

Numerical results reveal that the slip front speed varies with a changing static stress state along the interface, which is coherent with experimental observation [1]. However, a static stress criterion does not seem to be sufficient to fully characterize the propagation speed of the interface rupture. Instead, we show that a dynamic energetic criterion, which relates the slip front speed with the relative rise of the energy density at the slip tip, captures all acquired data [5]. We also discuss the transition from sticking to sliding at the frictional interface, which is marked by the occurrence of local slip events, called slip precursors. These initiate at shear levels much below the global static friction coefficient threshold. These precursors stop before propagating over the entire interface, and their length increases with increasing shear force, which can be fully predicted by linear elastic fracture mechanics. We also show that the propagation of a given slip event is significantly influenced by the slip history on the interface [6]. Interestingly, the heterogeneous state of stress at the interface created by each precursor event cumulate, leading to highly non-uniform interface stresses by the time the rupture propagates through the complete interface (macroscopic sliding).

References :

 

[1] O. Ben-David, G. Cohen, and J. Fineberg, The dynamics of the onset of frictional slip, Science, 330(6001):211, 2010.

[2] V. Prakash and R.J. Clifton, Time resolved dynamic friction measurements in pressure-shear, ASME, Experimental Techniques in the Dynamics of Deformable Solids, 165, 33-48, 1993.

[3] A. Cochard and J.R. Rice, Fault rupture between dissimilar materials: Ill-posedness, regularization, and slip-pulse response, J. Geophys. Res., 105(B11):25891, 2000.

[4] D.S. Kammer, V.A. Yastrebov, G. Anciaux, and J.F. Molinari, The existence of a critical length scale in regularized friction, Journal of the Mechanics and Physics of Solids, 63 (1), 40-50, 2014.

[5] D.S. Kammer, V.A. Yastrebov, P.Spijker, and J.F. Molinari, On the propagation of slip fronts at frictional interfaces, Tribol. Lett., 48(1), 27-32, 2012.

[6] M. Radiguet, D.S. Kammer, P. Gillet, and J.F. Molinari, Survival of heterogeneous stress distributions created by precursory slip at frictional interfaces, Phys. Rev. Lett., 111 (16), 164302, 2013.

Type :
Séminaires - conférences
Lieu(x) :
Campus de Cachan
Amphi e-média
Bâtiment Léonard De Vinci de - ENS Cachan
61, avenue du Président Wilson 94230 Cachan
Plan d'accès

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