Acquisition of Acoustic Emission Signals from Rocks Using Directly Bonded PZT Patches

Abstract

Acoustic emission (AE) technique is a proven effective technique for monitoring underground mines and caverns. With the advancement in the data acquisition technology, AE signals up to 2–5 MHz of frequency can be recorded successfully. However, this generates a lot of data to be analyzed and stored. This paper presents a concept of a simple and cost-effective, low-frequency AE technique for monitoring damages in the rocks. The tests were performed on Kota sandstone rock specimens in compression at three different displacement rates of 0.01, 0.05 and 0.1 mm/s. The AE signals were recorded successfully through thin square piezo-patches (used as the AE transducers) and a commercially available sound card for data logging. The proposed technique has been found to be easy and very much cost-effective in capturing low-frequency AE signals. The recorded data were processed for determining different AE parameters like cumulative AE count, relative energy of an event and event rate.