Jacob's Ladder http://
１ｓｔ LIVE 9.20 NAGOYA paradice cafe 21 20:00〜
Acoustic Emission Band†Jacob's Ladder†
Acoustic Emission phenomena
AEs are commonly defined as transient elastic waves
within a material caused by
the release of localized stress energy.
Hence, an event source is the phenomenon
which releases elastic energy into the material,
which then propagates as an elastic wave.
Acoustic emissions can be detected in
frequency ranges under
1 kHz, and have been reported at frequencies up to
100 MHz. Rapid stress-releasing events generate a
spectrum of stress waves starting at
0 Hz and typically falling off at several MHz.
AE is related to an irreversible release of energy, and can be generated
from sources not involving material failure including friction,
cavitation and impact.
Additionally, events can also come quite rapidly when materials begin to fail,
in which case AE activity rates are studied as opposed to individual events.
AE events that are commonly studied among material failure processes
include the extension of a fatigue crack, or fiber breakage in
a composite material.