Abstract
In the literature there have appeared a lot of works with regard to acoustic emission (AE) signals observed in a frequency range below a few MHz. In this paper we describe a new system for measuring AE signals in the frequency range up to 100 MHz. By using piezoelectric thin-film transducers fabricated on the end surfaces of rectangular bars of glass samples which have been notched, the AE signals radiated from the crack can be detected during conventional three point bending test. The output signal of each transducer is amplified and A/D converted at a sampling rate of 200 MHz. The power spectrum of each AE signal and the coherence function between the two signals are obtained by using a computer. The new AE measurement system in VHF range developed here can be applied in a new research field to be called micro-AE spectroscopy.
