Cracks cleave crystalsM. Marder
Center for Nonlinear Dynamics and Department of Physics The University of Texas at Austin - Austin, TX 78712, USA
(Received 20 October 2003; accepted in final form 2 March 2004)
The problem of finding what direction cracks should move is not completely solved. A commonly accepted way to predict crack directions is by computing the density of elastic potential energy stored well away from the crack tip, and finding a direction of crack motion to maximize the consumption of this energy. I provide in this letter a specific case where this rule fails. The example is of a crack in a crystal. It fractures along a crystal plane, rather than in the direction normally predicted to release the most energy. Thus, a correct equation of motion for brittle cracks must take into account both energy flows that are described in conventional continuum theories and details of the environment near the tip that are not.
46.50.+a - Fracture mechanics, fatigue and cracks.
62.20.Mk - Fatigue, brittleness, fracture, and cracks.
81.40.Np - Fatigue, corrosion fatigue, embrittlement, cracking, fracture and failure.
© EDP Sciences 2004