George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801 Ferst Drive, Atlanta, Georgia 30332-0405, USA.
J Acoust Soc Am. 2009 Dec;126(6):2939-48. doi: 10.1121/1.3243467.
The ultrasonic backward beam displacement, which has been shown to occur when a bounded beam is incident upon a periodically corrugated liquid-solid interface, is studied experimentally. This effect has been previously studied on a periodic water-brass interface at one particular frequency (6 MHz) and one corresponding angle of incidence (22.5 degrees), but the question has remained whether it would also exist at other frequency and angle combinations. The knowledge of whether this phenomenon is a coincidence or whether it will occur for other frequency and angle combinations contributes to a better understanding of the interaction of ultrasound with periodic structures and diffraction effects, in particular. Potential applications exist in the study of phononic crystals and in the non-destructive evaluation of materials. The present work reports results from recent experiments on the same periodically grooved brass sample that was employed in the first investigations of this phenomenon. Through the examination of frequency spectra in the form of angular and classical spectrograms, the experiments reported here show the backward beam displacement to occur for multiple angles of incidence and frequencies. Furthermore, evidence is shown as to the exact cause of the backward beam displacement, namely, a backward propagating Scholte-Stoneley wave.
当一束有界光束入射到周期性波纹的液-固界面时，会出现超声反向束位移，对此我们进行了实验研究。该效应之前曾在一个特定频率（6MHz）和一个相应的入射角（22.5 度）的周期性水-黄铜界面上进行过研究，但问题仍然是它是否也会在其他频率和角度组合下存在。了解这种现象是巧合还是会在其他频率和角度组合下发生，有助于更好地理解超声波与周期性结构和衍射效应的相互作用，特别是在声子晶体的研究和材料的无损评估中。本工作报道了最近在第一个该现象研究中使用的相同周期性波纹黄铜样本上的实验结果。通过以角度和经典声谱图的形式检查频谱，这里报告的实验表明，反向束位移会在多个入射角和频率下发生。此外，还展示了反向束位移的确切原因，即反向传播的 Scholte-Stoneley 波。
