Understanding Acoustic Emission Testing- Reading 1 Part B-A

Wave Propagation
A primitive wave released at the AE source
is illustrated in the figure right. The
displacement waveform is a step-like
function corresponding to the permanent
change associated with the source process.
The analogous velocity and stress
waveforms are essentially pulse-like. The
width and height of the primitive pulse
depend on the dynamics of the source
process. Source processes such as
microscopic crack jumps and precipitate
fractures are usually completed in a fraction
of a microsecond or a few microseconds,
which explains why the pulse is short in
duration. The amplitude and energy of the
primitive pulse vary over an enormous range
from submicroscopic dislocation movements
to gross crack jumps.
Charlie Chong/ Fion Zhang