AE technology involves the use of ultrasonic transducers (20Khz-1Mhz) to listen for the sounds of failure occurring in materials and structures. Crack growth due to fatigue, hydrogen embrittlement, stress corrosion, and creep can be detected and located by the use of AE technology. In addition high pressure leaks can also be detected and located. AE technology is also finding wide application in the nondestructive testing for structural integrity of composite materials and structures made from composite materials. Fiber breakage, matrix cracking, and delamination are three mechanisms that can produce AE signals when stress is applied to the material or structure.

Harold L. Dunegan, President of Dunegan Engineering Consultants Inc.(DECI), is a pioneer in the field of Acoustic Emission. His original research and subsequent publications by he and his co-workers at Lawrence Livermore Laboratory in the 1960s led to world wide acceptance of Acoustic Emission as a new tool for nondestructive testing of materials and structures. Mr. Dunegan founded Dunegan Research Corporation in 1968 and became the first company to exclusively produce acoustic emission instrumentation for sale to world wide markets. The testing techniques and instrumentation concepts produced under his leadership are still being incorporated in acoustic emission instrumentation being produced today. A measure of the quality and durability of this equipment is evidenced by the fact that much of this original equipment is still being used throughout the world.

The transducer and instrumentation concepts designed 20 years ago and still being used today have worked well for numerous applications related to the testing of metal and composite pressure boundaries, and composite man lift booms. These concepts have not been as successful for the testing of large structures such as bridges, off-shore platforms, and aircraft due to the difficulty in separating crack produced AE signals from extraneous noise sources.

The AESMART 2000 is a new portable instrument being produced by DECI that will solve these traditional problems. It will eliminate extraneous noise sources before they enter the data base, and will for the first time with any AE instrumentation give information regarding the depth of a growing crack in a plate. Traditional instrumentation techniques as well as more recent AE techniques based on modal analysis of the AE signal store all data and attempt to separate crack like signals from noise with pattern recognition software. This approach requires expensive fast digital techniques for capture of the signals, and enormous amount of storage when attempting to separate valid signals in noisy environments. In addition it is further limited by being a "post test" analysis rather than a real time method, and is not very portable.

Check out the AESMART 2000 in the DECI TRANSDUCERS & INSTRUMENTATION section.