An array is an organized arrangement of large quantities of an object. The simplest form of an ultrasonic array for NDT would be a series of several single element transducers arranged in such a way as to increase inspection coverage and/or the speed of a particular inspection. Examples of this include:
-- Tube inspection, where multiple probes are often used for both crack detection, finding laminar flaws, and overall thickness measurement
-- Forged metal parts, which often require multiple probes focused at different depths to enable detection of small defects in a zonal manner.
-- A linear arrangement of probes along a surface to increase detection of laminar flaws in composites or corrosion in metals.
These inspections require high speed multi-channel ultrasonic equipment with proper pulsers, receivers, and gate logic to process each channel as well as careful fixturing of each transducer to properly set up the inspection zones.
In its simplest form, one can thick of a phased array probe as a series of individual elements in one package. While the elements in reality are much smaller than conventional transducers, these elements can be pulsed as a group so as to generate directionally controllable wavefronts. This "Electronic Beam Forming" allows multiple inspection zones to be programmed and analyzed at very high rates of speed from a single position transducer. This is discussed in greater detail in later
pages.
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Inside a Phased Array Transducer >>