Ultrasonic Testing of Materials

Surface Acoustic Wave Determination of Hardness: Forward Problem

“…Rosen [4] found a quadratic correlation between changes in hardness and ultrasonic velocity, whereas he found a linear correlation between hardness and ultrasonic attenuation in age hardened 160 AI-Cu alloy. Krautkramer and Krautkramer [5] cite a number of German articles to support the claim that hardness can be related to acoustic velocity or attenuation and empirically determined from them when all other variables are kept constant. They also assert that treatments of steel, such as quenching and tempering have a greater effect on acoustic velocity than do variations in composition of alloying elements.…”

Impacts as a source of acoustic pulse-echo energy for nondestructive testing of concrete structures

“…Piezoelectric plates vibrate in numerous fundaiuetal modes vi their respective harmonics when the crystal is excited (Kraw°.amer and Krautkramer 1977). An interesting fact that may be useful for impact-echo measurements is that: the Q, which is inversely related to the damping factor, decreases with the order of the harmonic.…”

“…UPE measurements, whether for concrete or other materials, require low Q (wide bandwidth) transducers for proper operation. However, it is possible to perform ultrasonic pulse-echo measurements at one of the harmonic frequencies of the transducer since the Q decreases as the order of the harmonic (Krautkramer and Krautkramer 1977). If a transducer is excited by a gated sine wave pulse with the center frequency of the pulse at the resonant frequency of the transducer, the transducer will respond around that frequency only.…”

“…The tests were made in a shallow water basin about 100 ft square into the concrete, reflect from the base of the concrete slab to the top surface of the concrete and to refract into the water to be received by the pressure gage (Krautkramer and Krautkramer 1977). Although rays of energy are emanating from the explosive source from many angles, there is only one particular angle and ray path that will satisfy 7nell's law of refraction and reflection in the water and concrete and permit detection at the receiver.…”

Ultrasonic monitoring of recrystallization: an example of in-situ process control with NDE

“…Generally, the piezoelectric effect is used to generate ultrasound [53]. However, the ultrasound produced by the piezoelectric transducer needs a coupling material to transmit the ultrasound into the sample, or the longitudinal wave generated by the piezoelectric effect can be coupled into the sample by using a water tank.…”