Measurement of shear wave attenuation coefficient using a contact pulse-echo method with consideration of partial reflection effects

Abstract

Accurate measurements of the ultrasonic shear wave attenuation coefficient are essential for the quantitative nondestructive evaluation of the microstructure of a material. This work provides an experimental technique for measuring this coefficient using a contact method. The first and second pulse-echo shear wave signals are measured and are used to calculate the frequency-dependent attenuation coefficient; in this process, the diffraction and the diffraction-affected partial reflection coefficient are corrected to improve the accuracy of measurement. The diffraction coefficient is calculated from measurements of the shear wave velocity, and the partial reflection coefficient is determined experimentally by using another transducer on the opposite side and taking into account wave diffraction effects. The shear wave attenuation coefficient is determined for samples of different thicknesses, and these results show good agreement over a broadband frequency, thus validating the proposed method. The advantage of discriminating the porosity of additive manufacturing materials using shear wave attenuation is demonstrated, and the practical benefits of accurately measuring the shear wave attenuation coefficient using the proposed method are also discussed.