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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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Attenuation - As it travels through a medium, the organized wave front<br />

generated by an ultrasonic transducer will begin to break down due to<br />

imperfect transmission of energy through the microstructure of any material.<br />

Organized mechanical vibrations (sound waves) turn into random mechanical<br />

vibrations (heat) until the wave front is no longer detectable. This process is<br />

known as sound attenuation. Attenuation varies with material, and increases<br />

proportionally to frequency. As a general rule, hard materials like metals are<br />

less attenuating than softer materials like plastics. Attenuation ultimately limits<br />

the maximum material thickness that can be measured with a given gage<br />

setup and transducer, since it determines the point at which an echo will be<br />

too small to detect.<br />

http://www.olympus-ims.com/en/ndt-tutorials/thickness_gage/transducers/beam_characteristics/

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