Applicability of Piezoelectric Ceramics to a Dipole Simulated AE Source.

The characteristics of a simulated AE source using piezoelectric ceramics were discussed. A small piezoelectric ceramic plate located near the crack tip of a chevron-notched PMMA specimen was subjected to a step voltage for generating simulated AE waves. AE waveforms due to piezoelectric ceramics were monitored with a 6-channel measurement system. A tensile test of the specimen was also conducted to investigate the correspondence with actual AE caused by crack extension. The radiation pattern of the simulated wave suggested the occurrence of mode I deformation at the simulated source. According to the moment tensor analysis, the direction of force was considered to be approximately normal to the crack surface. It is found that although there are a few types of deformation during crack extension, the simulated AE source using piezoelectric ceramics has the same main component as one of those in the fracture. The simulated AE source using piezoelectric ceramics is equivalent to the dipole source of mode I deformation.