DISLOCATION MECHANISM OF ACOUSTIC-EMISSION FROM AN AXISYMMETRICAL CRACK

A model is proposed for acoustic emission from a fine axisymmetric crack growing in an unbounded, homogeneous, isotropic elastic medium. The expansion of the crack is interpreted as a process where fluxes of prismatic dislocation loops from within the volume of the medium are annihilated at the surfaces (edges) of the crack, accompanied by the transition radiation of sound. The law governing the time variation of the radius of the loop R = R0(t) is assumed to be known. Equations are derived to describe the space-time evolution of the velocity field of points of the medium and the stress field in the wave zone at large distances r much greater than R0 from the crack.