Dynamics of Crack Propagation in Brittle Materials

(Received 13 October 1995, revised 6 May 1996, accepted 2 July 1996)

Abstract
An experimental study of the properties of crack propagation in brittle materials is described. Specifically the crack speed, the sound emission and the fracture profile have been measured as a function of the applied stress. We find that the local velocity can be considered as a control parameter which determines the properties of the crack. The steady state velocity turns out to be a function of the applied stress. Several thresholds have been identified. One corresponds to the presence of a weak sound emission associated with velocity oscillations and another one to the onset of the surface roughness associated with velocity oscillations and another one to the onset of the surface roughness associated with a strong sound emission. We also find a strong crosscorrelation between sound and velocity oscillations. The statistical properties of the fracture profile depend on the steady state velocity