Faculty of Civil Engineering and Geosciences, Department of Geotechnology, Delft University of Technology, Stevinweg 1, 2628 CN Delft, The Netherlands.
J Acoust Soc Am. 2011 Sep;130(3):1299-312. doi: 10.1121/1.3605537.
The interface-wave impedance and ellipticity are wave attributes that interrelate the full waveforms as observed in different components. For each of the fluid/elastic-solid interface waves, i.e., the pseudo-Rayleigh (pR) and Stoneley (St) waves, the impedance and ellipticity are found to have different functional dependencies on Young's modulus and Poisson's ratio. By combining the attributes in a cost function, unique and stable estimates of these parameters can be obtained, particularly when using the St wave. In a validation experiment, the impedance of the laser-excited pR wave is successfully extracted from simultaneous measurements of the normal particle displacement and the fluid pressure at a water/aluminum interface. The displacement is measured using a laser Doppler vibrometer (LDV) and the pressure with a needle hydrophone. Any LDV measurement is perturbed by refractive-index changes along the LDV beam once acoustic waves interfere with the beam. Using a model that accounts for these perturbations, an impedance decrease of 28% with respect to the plane wave impedance of the pR wave is predicted for the water/aluminum configuration. Although this deviation is different for the experimentally extracted impedance, there is excellent agreement between the observed and predicted pR waveforms in both the particle displacement and fluid pressure.
界面波阻抗和椭圆率是与不同分量中观测到的全波相关联的波动属性。对于每种流体/弹性固体界面波，即拟瑞利波 (pR) 和斯通利波 (St)，阻抗和椭圆率都发现与杨氏模量和泊松比具有不同的函数依赖性。通过在成本函数中组合这些属性，可以获得这些参数的独特且稳定的估计值，特别是在使用 St 波时。在验证实验中，通过同时测量水/铝界面上的法向粒子位移和流体压力，成功地从激光激发的 pR 波的测量中提取了阻抗。位移使用激光多普勒测振仪 (LDV) 测量，压力使用针状水听器测量。一旦声波与光束相互干扰，任何 LDV 测量都会受到沿 LDV 光束的折射率变化的干扰。使用考虑到这些干扰的模型，对于水/铝配置，预测 pR 波的平面波阻抗会降低 28%。尽管这种偏差对于实验提取的阻抗是不同的，但在粒子位移和流体压力方面，观察到的和预测的 pR 波形之间存在极好的一致性。
