 
Summary: Generalized Griffith criterion for dynamic fracture and the stability of crack motion
at high velocities
M. AddaBedia,1
R. Arias,2
M. Ben Amar,1
F. Lund2
1
Laboratoire de Physique Statistique de l'Ecole Normale Supe´rieure, 24 rue Lhomond, F75231 Paris Cedex 05, France
2
Departamento de Fi´sica, Facultad de Ciencias Fi´sicas y Matema´ticas, Universidad de Chile, Casilla 4873, Santiago, Chile
Received 18 November 1998
We use Eshelby's energy momentum tensor of dynamic elasticity to compute the forces acting on a moving
crack front in a threedimensional elastic solid Philos. Mag. 42, 1401 1951 . The crack front is allowed to be
any curve in three dimensions, but its curvature is assumed small enough so that near the front the dynamics
is locally governed by twodimensional physics. In this case the component of the elastic force on the crack
front that is tangent to the front vanishes. However, both the other components, parallel and perpendicular to
the direction of motion, do not vanish. We propose that the dynamics of cracks that are allowed to deviate from
straight line motion is governed by a vector equation that reflects a balance of elastic forces with dissipative
forces at the crack tip, and a phenomenological model for those dissipative forces is advanced. Under certain
assumptions for the parameters that characterize the model for the dissipative forces, we find a second order
