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

• Published in: Chinese physics B Vol. 19; no. 7; pp. 350 - 357
• Main Author: 姚桂锦 吕卫国 宋若龙 崔志文 张香林 王克协
• Format: Journal Article
• Language: English
• Published: IOP Publishing 01.07.2010
• Subjects: Acoustic impedance; Attenuation; Density; Error analysis; Foundations; Mathematical analysis; Thin films; Transfer functions; 传递函数; 测定方法; 测量记录; 纵向速度; 线性粘弹性; 质量密度; 超声波
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/19/7/074301

This paper proposes a method of simultaneous determination of the four layer parameters （mass density, longitudinal velocity, the thickness and attenuation） of an immersed linear-viscoelastic thin layer by using the normally-incident reflected and transmitted ultrasonic waves. The analytical formula of the layer thickness related to the measured trans- mitted transfer functions is derived. The two determination steps of the four layer parameters are developed, in which acoustic impedance, time-of-flight and attenuation are first determined by the reflected transfer functions. Using the derived formula, it successively calculates and determines the layer thickness, longitudinal velocity and mass density by the measured transmitted transfer functions. According to the two determination steps, a more feasible and simplified measurement setups is described. It is found that only three signals （the reference waves, the reflected and transmitted waves） need to be recorded in the whole measurement for the determination of the four layer parameters. A study of the stability of the determination method against the experimental noises and the error analysis of the four layer parameters are made. This study lays the theoretical foundation of the practical measurement of a linear-viscoelastic thin layer.