D. Guggenheim School of Aerospace Engineering, Georgia Institute of Technology, 270 Ferst Drive, Atlanta, Georgia 30332, USA.
J Acoust Soc Am. 2011 Oct;130(4):1899-907. doi: 10.1121/1.3626165.
A frequency selective acoustic transducer (FSAT) is proposed for directional sensing of guided waves. The considered FSAT design is characterized by a spiral configuration in wavenumber domain, which leads to a spatial arrangement of the sensing material producing output signals whose dominant frequency component is uniquely associated with the direction of incoming waves. The resulting spiral FSAT can be employed both for directional sensing and generation of guided waves, without relying on phasing and control of a large number of channels. The analytical expression of the shape of the spiral FSAT is obtained through the theoretical formulation for continuously distributed active material as part of a shaped piezoelectric device. Testing is performed by forming a discrete array through the points of the measurement grid of a scanning laser Doppler vibrometer. The discrete array approximates the continuous spiral FSAT geometry, and provides the flexibility to test several configurations. The experimental results demonstrate the strong frequency dependent directionality of the spiral FSAT and suggest its application for frequency selective acoustic sensors, to be employed for the localization of broadband acoustic events, or for the directional generation of Lamb waves for active interrogation of structural health.
提出了一种频率选择声换能器（FSAT），用于导波的定向传感。所考虑的 FSAT 设计的特点是在波数域中采用螺旋配置，这导致了传感材料的空间布置，产生输出信号，其主要频率分量与入射波的方向唯一相关。由此产生的螺旋 FSAT 可用于导波的定向传感和产生，而无需依赖于大量通道的相位和控制。通过将连续分布的有源材料作为形状压电器件的一部分的理论公式，获得了螺旋 FSAT 形状的解析表达式。通过扫描激光多普勒测振仪的测量网格点形成离散阵列来进行测试。离散阵列近似于连续螺旋 FSAT 几何形状，并提供了测试多个配置的灵活性。实验结果证明了螺旋 FSAT 的强频率相关方向性，并建议将其应用于频率选择声传感器，用于宽带声事件的定位，或用于兰姆波的定向产生，以主动检测结构健康状况。
