Driven by the pulser, the transducer generates high frequency ultrasonic energy.
The sound energy is introduced and propagates through the materials in the form
of waves. When there is a discontinuity (such as a crack) in the wave path, part
of the energy will be reflected back from the flaw surface. The reflected wave signal
is transformed into an electrical signal by the transducer and is displayed on a
screen. In the applet below, the reflected signal strength is displayed versus the
time from signal generation to when a echo was received. Signal travel time can
be directly related to the distance that the signal traveled. From the signal, information
about the reflector location, size, orientation and other features can sometimes
be gained.
The technique is also commonly used to determine the thickness of the test
object, for example, to monitor pipework corrosion.
Ultrasonic testing uses high frequency, highly directional sound waves to measure
material thickness, find hidden internal flaws, or analyze material properties in
metals, plastics, composites, ceramics, rubber, and glass. Using frequencies beyond
the limit of human hearing, ultrasonic instruments generate shorts bursts of sound
energy that are coupled into the test piece, and the instrument monitors and analyzes
reflected or transmitted wave patterns to generate test results.
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