Summary: Journal of the Mechanics and Physics of Solids
52 (2004) 14071420
Brittle fracture dynamics with arbitrary paths.
II. Dynamic crack branching under general
Laboratoire de Physique Statistique de l'Ecole Normale SupÃerieure, 24 rue Lhomond,
F-75231 Paris Cedex 05, France
Received 12 June 2003; accepted 15 October 2003
The dynamic propagation of a bifurcated crack under antiplane loading is considered. The
dependence of the stress intensity factor just after branching is given as a function of the stress
intensity factor just before branching, the branching angle and the instantaneous velocity of the
crack tip. The jump in the dynamic energy release rate due to the branching process is also
computed. Similar to the single crack case, a growth criterion for a branched crack is applied.
It is based on the equality between the energy ux into each propagating tip and the surface
energy which is added as a result of this propagation. It is shown that the minimum speed of
the initial single crack which allows branching is equal to 0:39c, where c is the shear wave
speed. At the branching threshold, the corresponding bifurcated cracks start their propagation at