Acoustic emissions from penny‐shaped cracks in glass. II. Moment tensor and source‐time function

摘要

In the second part of this paper we describe both epicentral and off‐epicentral responses corresponding to the acoustic emission (AE) source of a Mode I type penny‐shaped crack generated by the indentation technique. The characteristics of the source are described in terms of the components of the moment tensor and its time function which were recovered from the waveforms coupled with an analysis of the AE radiation pattern described in Part I of this paper [J. Appl. Phys. 59, 2704 (1986)]. The recovered source characteristics indicate that the dominant contribution to the AE source of the penny‐shaped crack comes from a single dipole acting normal to the crack plane whose temporal characteristics resemble those of a terminated parabolic ramp function.