A Wireless Data Acquisition System for Acoustic Emission Monitoring

Abstract

As SHM researchers have gone about trying to determine the best methods of damage prognosis in civil, mechanical, and aerospace structures, acoustic emission (AE) testing has emerged as a technique that can provide an estimate of the location, severity, and type of damage in a structure. AE methodologies use stress waves generated by the mechanical deformation of a monitored material to detect the presence and severity of damage locations. AE techniques, which involve the analysis of frequency content between 1 kHz and 1 MHz, have proven effective in detecting the onset of cracking and other early-stage failure in active structures such as airplanes in flight, but they suffer from the need for large numbers of sensors to be deployed on a monitored structure. Outside of the laboratory, AE methods have additional drawbacks that have hampered their adoption in real-world SHM applications. Primarily, these approaches require traditionally bulky and expensive equipment, as well as a data acquisition system that can sample and store sensor data at very high sampling rates (up to 25MHz). As a result, per-sensor costs and unrealistic data acquisition requirements have hampered the market adoption of this approach to SHM. In this paper, a new low-cost wireless data acquisition system is presented that is capable of collecting, storing, and wirelessly transmitting AE data at rates of up to 12.5MHz. This battery-powered device has a very small form factor, includes a four-bit software-selectable gain stage, and has been designed with the ability to process AE data as it is collected, improving its battery life and allowing its wireless connection to only be used when one of a set of trigger events have been detected.