Deng Mingxi
Department of Physics, Logistics Engineering University, No. 174, Chang Jiang 2 Road, Chongqing 400016, People's Republic of China.
Ultrasonics. 2006 Dec 22;44 Suppl 1:e1157-62. doi: 10.1016/j.ultras.2006.05.158. Epub 2006 Jun 8.
A nonlinear Lamb wave approach is presented for characterizing the surface properties of a solid plate. This characterization approach is useful for some practical situations where ultrasonic transducers cannot touch the surfaces to be inspected, e.g. the inside surfaces of sealed vessels. In this paper, the influences of changes in the surface properties of a solid plate on the effect of second-harmonic generation by Lamb wave propagation were analyzed. A surface coating with the different properties was used to simulate changes in the surface properties of a solid plate. When the areas and thicknesses of coatings on the surface of a given solid plate changed, the amplitude-frequency curves both of the fundamental waves and the second harmonics by Lamb wave propagation were measured under the condition that Lamb waves had a strong nonlinearity. It was found that changes in the surface properties might clearly affect the efficiency of second-harmonic generation by Lamb wave propagation. The Stress Wave Factors (SWFs) in acousto-ultrasonic technique were used for reference, and the definitions of the SWFs of Lamb waves were introduced. The preliminary experimental results showed that the second-harmonic SWF of Lamb wave propagation could effectively be used to characterize changes in the surface properties of the given solid plate.
提出了一种用于表征固体板表面特性的非线性兰姆波方法。这种表征方法对于某些实际情况很有用，例如超声换能器无法接触待检测表面的情况，如密封容器的内表面。本文分析了固体板表面特性的变化对兰姆波传播产生二次谐波效应的影响。使用具有不同特性的表面涂层来模拟固体板表面特性的变化。当给定固体板表面涂层的面积和厚度发生变化时，在兰姆波具有强非线性的条件下，测量了兰姆波传播的基波和二次谐波的幅频曲线。发现表面特性的变化可能会明显影响兰姆波传播产生二次谐波的效率。以声超声技术中的应力波因子（SWF）为参考，引入了兰姆波SWF的定义。初步实验结果表明，兰姆波传播的二次谐波SWF可有效用于表征给定固体板表面特性的变化。
