Pereira Daniel, Haiat Guillaume, Fernandes Julio, Belanger Pierre
Department of Mechanical Engineering, École de technologie supérieure, 1100 Rue Notre-Dame O, Montreal, Quebec, H3C1K3, Canada.
CNRS, Laboratoire Modélisation et Simulation Multiechelle, UMR CNRS 8208, 61 avenue du Général de Gaulle, Créteil Cedex, 94010, France.
J Acoust Soc Am. 2017 Apr;141(4):2538. doi: 10.1121/1.4979695.
Axial transmission techniques have been extensively studied for cortical bone quality assessment. However, the modeling of ultrasonic guided waves propagation in such a complex medium remains challenging. The aim of this paper is to develop a semi-analytical finite element method to simulate the propagation of guided waves in an irregular, multi-layer, and heterogeneous bone cross-section modeled with anisotropic and viscoelastic material properties. The accuracy of the simulations was verified against conventional time-domain three-dimensional finite element. The method was applied in the context of axial transmission in bone to investigate the feasibility of first arrival signal (FAS) to monitor degradation of intracortical properties at low frequency. Different physiopathological conditions for the intracortical region, varying from healthy to osteoporotic, were monitored through FAS velocity using a 10-cycle tone burst excitation centered at 32.5 kHz. The results show that the variation in FAS velocity is mainly associated with four of the eight modes supported by the waveguide, varying with velocity values between 550 and 700 m/s along the different scenarios. Furthermore, the FAS velocity is shown to be associated with the group velocity of the mode with the highest relative amplitude contribution at each studied scenario. However, because of the evolution of the mode with the highest contribution, the FAS velocity is shown to be limited to discriminate intracortical bone properties at low frequency.
轴向传输技术已被广泛研究用于皮质骨质量评估。然而，超声导波在如此复杂介质中的传播建模仍然具有挑战性。本文的目的是开发一种半解析有限元方法，以模拟导波在具有各向异性和粘弹性材料特性的不规则、多层和非均质骨截面中的传播。通过与传统的时域三维有限元方法对比，验证了模拟的准确性。该方法应用于骨的轴向传输情况，以研究首次到达信号（FAS）在低频下监测皮质内特性退化的可行性。使用以32.5kHz为中心的10周期短脉冲激励，通过FAS速度监测皮质内区域从健康到骨质疏松的不同生理病理状况。结果表明，FAS速度的变化主要与波导所支持的八种模式中的四种相关，在不同情况下速度值在550至700m/s之间变化。此外，在每个研究的情况下，FAS速度显示与相对振幅贡献最高的模式的群速度相关。然而，由于贡献最大的模式的演变，FAS速度在低频下显示出区分皮质内骨特性的局限性。
