| Originally conceived as an NDT tool for pressure vessels, Acoustic Emission testing (AE) has become much wider in scope. We now apply it to all
types of process monitoring as well as for its original purposes of flaw detection and structural integrity inspection.
 AE
sensors respond with amazing sensitivity to motion in the low ultrasonic
frequency range (10 kHz - 2000 kHz). Motions as small as 10-12
inches and less can be detected. These sensors can hear the breaking
of a single grain in a metal, a single fiber in a fiber-reinforced composite,
and a tiny gas bubble from a pinhole leak as it arrives at the liquid
surface. By detecting sources as small as these, or as large as
brittle crack advance, AE technology warns of danger, informs about structural
health and watches over costly and critical processes.
AE technology also offers unique capabilities. It basically detects acoustic waves that are generated by sudden movement in solid materials. At the
frequencies we use, the distance between the AE source and the sensor could be as little as a few inches or as much as tens or even hundreds of feet. Sudden
sub-critical local failures in materials under stress are the classic sources of AE.
The technology is used to safeguard against catastrophic failures, to assess structural integrity and to enhance safety in a wide range of structures from
fiberglass tanks to bucket trucks, from bridges and aircraft to high-pressure gas cylinders. On the process monitoring side, AE is used for a wide range of
applications including leak detection, particle impacts, electrical discharges and a variety of friction-type processes, just to name to most common. Current
areas of interest that REACT is involved in include higher-frequency machinery health monitoring and predictive diagnosis.
Over the last five years, AE instruments have transitioned to a new architectural concept based on digital signal processing, that opens up a whole new range of
technical capabilities for the AE method. The frequency domain is now readily accessible. Full waveform capture now allows advanced, post-test analysis of
waveforms that were previously reduced in real-time to a small set of half-a-dozen features measured with bulky electronic circuits. Having invested in
circuit-mount manufacturing technology nearly ten years ago, PAC has made some extraordinary achievements in developing much more compact and significantly more
powerful AE instrumentation than has ever been available before. These advances in equipment have also allowed our REACT department to use the AE technology to
ensure our customers get the best service available.
Our REACT scientists use their skills, along with PAC's advanced equipment, to create new AE applications with and for our customers. We also support and
consult on a wide variety of relatively conventional applications. Along with the company's experienced engineering staff, REACT undertakes development projects
to deliver unique AE instruments for use in production or in periodic testing. Under our education and training program, we have taught AE technology in
week-long courses delivered to over a thousand NDT technicians, engineers and scientists. |
