APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010;
Portland, Oregon
Session H32: Focus Session: Tribophysics -- Fracture and Plasticity
8:00 AM–11:00 AM,
Tuesday, March 16, 2010
Room: E142
Sponsoring
Units:
GSNP DMP
Chair: Bernd Gotsmann, IBM Zurich
Abstract ID: BAPS.2010.MAR.H32.7
Abstract: H32.00007 : Failure of disordered materials as a depinning transition
9:12 AM–9:48 AM
Preview Abstract
Abstract
Author:
Laurent Ponson
(California Institute of Technology)
Crack propagation is the fundamental process leading to
material failure. However, its dynamics is far from being fully
understood. In this work, we investigate both experimentally
and theoretically the far-from-equilibrium propagation of a
crack within a disordered brittle material. At first, we focus
on the average dynamics of a crack, and study the variations of
its growth velocity $v$ with respect to the external driving
force $G$ [1]. Carefully measured on a brittle rock, these
variations are shown to display two regimes: above a given
threshold $G_c$, the velocity evolves as a power law $v \sim (G-
G_c)^{0.8}$, while at low driving force, its variations are
well described by a sub-critical creep law, characteristic of a
thermally activated crack propagation. Extending the continuum
theory of Fracture Mechanics to inhomogeneous media, we show
that this behavior is reminiscent of a dynamical critical
transition: critical failure occurs when the driving force is
sufficiently large to depin the crack front from the material
heterogeneities.
Another way to reveal such a transition is to investigate the
fluctuations of crack velocity [2]. Considering a crack at the
heterogeneous interface between two elastic solids, we predict
that its propagation occurs through sudden jumps, with power
law distributed sizes and durations. These predictions compare
quantitatively well with recent direct observations of
interfacial crack propagation [3].
Such an interpretation of material failure opens new
perspectives in the field of Engineering and Applied Science
that will be finally discussed.
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[1] L. Ponson, Depinning transition in failure of
inhomogeneous brittle materials, Phys. Rev. Lett. {\bf 103},
055501 (2009).
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[2] D. Bonamy, S. Santucci and L. Ponson, Crackling
dynamics in material failure as a signature of a self-organized
dynamic phase transition, Phys. Rev. Lett. {\bf 101}, 045501
(2008).
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[3] K.J. M{\aa}l{\o}y, S. Santucci, J. Schmittbuhl and R.
Toussaint, Local waiting time fluctuations along a randomly
pinned crack front, Phys. Rev. Lett. {\bf 96}, 045501 (2006).
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.H32.7