P.M. Rady Department of Mechanical Engineering, University of Colorado Boulder, Boulder, USA.
G.W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, USA.
Ultrasonics. 2021 May;113:106343. doi: 10.1016/j.ultras.2020.106343. Epub 2021 Jan 16.
We experimentally investigate and characterize high order Lamb wave modes in a dry human skull. Specifically, we show that the diploë supports distinct wave modes in the sub-1.0 MHz frequency regime, and we employ these modes for the estimation of equivalent mechanical properties of cortical and trabecular bones. These modes are efficiently generated in a parietal region by direct contact excitation with a wedge beam transducer, and are recorded via infrared laser vibrometry. Frequency/wavenumber data are estimated using a matrix pencil method applied to wavefield measurements recorded on the outer cortical surface. The semi-analytical finite element model of an equivalent three-layered plate provides the platform for the identification of wave modes based on their through-the-thickness profiles, and supports the estimation of equivalent mechanical properties in conjunction with an optimization algorithm developed for this purpose. The results presented herein illustrate how high order Lamb waves can be used to gain understanding of the wave properties of a human skull and to estimate the orthotropic and equivalent isotropic mechanical properties of cortical and trabecular bones.
我们通过实验研究和描述了干燥人类颅骨中的高阶 Lamb 波模式。具体而言，我们表明板障在亚 1.0MHz 频率范围内支持独特的波模式，并且我们利用这些模式来估计皮质骨和松质骨的等效机械性能。这些模式通过楔形波束换能器的直接接触激励在顶骨区域中高效地产生，并通过红外激光测振仪进行记录。使用应用于记录在外部皮质表面上的波场测量的矩阵束方法估计频率/波数数据。基于等效三层板的半解析有限元模型为根据其贯穿厚度分布识别波模式提供了平台，并支持与为此目的开发的优化算法一起估计等效机械性能。本文提出的结果说明了如何利用高阶 Lamb 波来深入了解人类颅骨的波特性，并估计皮质骨和松质骨的各向异性和等效各向同性机械性能。
