Group velocity and characteristic wave curves of Lamb waves in composites: Modeling and experiments
Group velocity and characteristic wave curves of Lamb waves in composites: Modeling and experiments
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DOI：
10.1016/j.compscitech.2006.09.023
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发表时间：
2007-06-01
影响因子：
9.1
通讯作者：
Yuan, F. G.
中科院分区：
文献类型：
--
作者：
Wang, Lei;Yuan, F. G.
对复合材料中兰姆波的传播特性进行了理论和实验研究，重点研究了兰姆波在复合材料中的群速度和特征波曲线。特别是，实验研究的重点是存在多个高阶Lamb波模式，这些模式可以在超声频率的激励下从压电传感器上观察到。利用三维弹性理论，数值求解了无限多个可能的波动模式下由超越方程所支配的精确频散关系。对于对称层合板，提出了一种通过在中面和顶面施加边界条件来分离对称和反对称波模的稳健方法。提出了一种新的计算复合材料中Lamb波群速度的半精确方法。同时，采用速度、慢度和波动三种特征波曲线来分析兰姆波传播的角度相关性。从理论上详细研究了兰姆波在两种不同类型的对称层合板中的频散和各向异性行为。在实验研究中，用窄带信号激励两个表面贴装的压电致动器的对称或反对称模式，并利用Gabor小波变换从压电传感器接收到的Lamb波的到达时间提取群速度。通过与理论和实验结果的比较，证实了压电致动器可以激发出多个高阶Lamb波，并且测得的群速度与三维弹性理论的结果符合得很好。(C)2006爱思唯尔有限公司。保留所有权利。
The propagation characteristics of Lamb waves in composites, with emphasis on group velocity and characteristic wave curves, are investigated theoretically and experimentally. In particular, the experimental study focuses on the existence of multiple higher-order Lamb wave modes that can be observed from piezoelectric sensors by the excitation of ultrasonic frequencies. Using three-dimensional (3-D) elasticity theory, the exact dispersion relations governed by transcendental equations are numerically solved for an infinite number of possible wave modes. For symmetric laminates, a robust method by imposing boundary conditions on the mid-plane and top surface is proposed to separate symmetric and anti-symmetric wave modes. A new semi-exact method is developed to calculate group velocities of Lamb waves in composites. Meanwhile, three characteristic wave curves: velocity, slowness, and wave curves are adopted to analyze the angular dependency of Lamb wave propagation. The dispersive and anisotropic behavior of Lamb waves in a two different types of symmetric laminates is studied in detail theoretically. In the experimental study, two surface-mounted piezoelectric actuators are excited either symmetric or anti-symmetric wave modes with narrowband signals, and a Gabor wavelet transform is used to extract group velocities from arrival times of Lamb wave received by a piezoelectric sensor. In comparison with the results from the theory and experiment, it is confirmed that multiple higher-order Lamb waves can be excited from piezoelectric actuators and the measured group velocities agree well with those from 3-D elasticity theory. (c) 2006 Elsevier Ltd. All rights reserved.