An ultrasonic method for determination of acoustic impedance, time of flight, and attenuation of a thin linear-viscoelastic layer

Abstract

Evaluation of gallium-indium alloy as an acoustic couplant for high-impedance, high-frequency applications ARLO 6, 125 (2005); 10.1121/1.1903025 Simultaneous determination of the mechanical moduli and mass of thin layers using nonadditive quartz crystal acoustic impedance analysis A method for the determination of acoustic impedance, time of flight, and attenuation of an immersed thin linear-viscoelastic layer on a substrate of infinite extent is proposed as the transfer functions of the normally incident ultrasonic reflected signals are given. Utilizing the derived analytical expressions related to the measured data, three parameters can be determined without considering the acoustic impedance of the substrate and giving the initial guesses and the corresponding convergence zones. The measurement relations between the layer properties and the three parameters are theoretically derived. The method stability against the experimental noises is numerically investigated.

Graphene oxide-stimulated acoustic attenuating performance of tungsten based epoxy films

“…where, Z, V and r are the acoustic impedance, velocity and density, respectively. 36 W/E films had a higher acoustic impedance value compared to W films, ascribed to the closer packed structure of W/E films than that of W films (Fig. 4d and e).…”

“…34 The attenuation is calculated by taking the transmission coefficients into account at the water-sample and samplewater interfaces, 35 and the acoustic impedance of the sample was obtained by the product of the velocity and density. 36 The density of each sample was calculated by using the measured weight and volume, with the volume determined by the Archimedes method.…”

Hierarchical Assembly of Tungsten Spheres and Epoxy Composites in Three-Dimensional Graphene Foam and Its Enhanced Acoustic Performance as a Backing Material

“…The velocity and attenuation are derived from the difference of flight and amplitude between the sample and water . The attenuation is calculated by taking the transmission coefficients into account at the water–sample and sample–water interfaces, and the acoustic impedance of the sample was obtained by the product of the velocity and density . The density of each sample was calculated by using the measured weight and volume, with the volume determined by the Archimedes method.…”

Determination of the parameters of a linear-viscoelastic thin layer using the normally-incident ultrasonic waves

“…Following Kinra and Lyer, [10] a dimensionless measure of attenuation, namely, β 2 is a material constant related to the quality factor Q by Q ∼ = π/β 2 as β 2 is small. From the simultaneous equation of the theoretical and the measured transmitted transfer functions H t (ω i ) and H * t (ω i ) (for discrimination, the superscript ( * ) refers to the measured quantity), after the condition that the phase-shift difference ∆ωψ 1 = (ω i+1 − ω i )ψ 1 being not greater than 2π is introduced to eliminate the ambiguity 074301-2 of phase-shift ω i ψ 1 , [18] by the derivation, the following expression is obtained:…”

“…Yao had derived the analytical formulas of acoustic impedance, time-of-flight and attenuation of a linearviscoelastic thin layer related to the transfer functions of the normally-incident reflected ultrasonic waves. [18] By using the analytical formulas, three parameters could be directly calculated and determined, however the coupling problem was not yet solved and the four layer parameters could not be simultaneously determined.…”