Depinning transition in failure of inhomogeneous brittle materials

Laurent Ponson (1, 2)

1 LABEST - Laboratorio d'Estruturas e Materiais
2 GALCIT - Graduate Aeronautical Laboratories

The dynamics of a crack propagating in an elastic inhomogeneous material is investigated. The variations of the average crack velocity with the external loading are measured for a brittle rock and are shown to display two distinct regimes: Below a given threshold Gc, the crack velocity is well described by an exponential law v ~ exp(−C/(G−G0)} characteristic of subcritical propagation, while for larger values of the driving force G > Gc, the velocity evolves as a power law v ~ (G − Gc)^theta with theta = 0.80 ± 0.15. These results can be explained extending the continuum theory of Fracture Mechanics to disordered systems. In this description, the motion of a crack is analogue to the one of an elastic line driven in a random medium and critical failure occurs when the loading is sufficiently large to depinne the crack front from the heterogeneities of the material.

Mots clés: Crack growth; Critical and subcritical propagation; Brittle fracture; Heterogeneous materials; Depinning transition; Elastic lines in random media

Domaines: Mécanique statistique [cond-mat.stat-mech]

Laurent Ponson. Depinning transition in failure of inhomogeneous brittle materials. Physical Review Letters, 2009, 103 (5), ⟨10.1103/PhysRevLett.103.055501⟩. ⟨hal-00278423v2⟩