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
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
P.O. Box 61808
Midland, TX 79711
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