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Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing, UT

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

Preparatory Notes for ASNT NDT Level III Examination - Ultrasonic Testing

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Note on Backing:<br />

The backing material supporting the crystal has a great influence on the<br />

damping characteristics of a transducer.<br />

Using a backing material with an impedance similar to that of the active<br />

element will produce the most effective damping. Such a transducer will have<br />

a wider bandwidth resulting in higher sensitivity.<br />

As the mismatch in impedance between the active element and the backing<br />

material increases, material penetration increases but transducer sensitivity is<br />

reduced.<br />

Keywords:<br />

Backing impedance mismatch small: Higher sensitivity<br />

Backing impedance mismatch high: Higher penetration.

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