A Note on the Velocity of Crack Propagation in Glass

JSGT 1952 V36 T297-T299

The writer believes that in this analysis lies a possible explanation for the existence of a maximum velocity of crack propagation in glass. This explanation may be stated quite simply as follows: the techniques used for measuring the velocity of crack propagation in glass are based on the assumption that the fractures are proceeding in straight lines. They are, in fact, incapable of measuring the velocities of cracks proceeding in any other manner. The positions of the fracture fronts in Barstow and Edgerton's experiments are determined by those fractures which are moving radially in straight lines as may be seen by examining their photographs. On this basis, then, the maximum measured velocity of crack propagation is equal to the maximum velocity at which a crack can continue to move in a straight line.

H. Rawson