Mohammadgholiha Masoud, Zonzini Federica, Moll Jochen, De Marchi Luca
IEEE Trans Ultrason Ferroelectr Freq Control. 2023 Nov;70(11):1494-1505. doi: 10.1109/TUFFC.2023.3305032. Epub 2023 Nov 1.
A novel directional transducer based on guided waves (GWs) is introduced in this article, designed for use in structural health monitoring (SHM) and acoustic data communication applications, i.e., systems in which the elastic medium serves as a transmission channel and information is conveyed through the medium via elastic waves. Such systems can overcome difficulties associated with traditional communication methods like wire-based or radio frequency (RF), which can be complex and have limitations in harsh environments or hard-to-reach places. However, the development of these techniques is hampered by GW dispersive and multimodal propagation and by multipath interference. The shortcomings can be effectively addressed by employing frequency steerable acoustic transducers (FSATs), which leverage their inherent directional capabilities. This can be achieved through the exploitation of a frequency-dependent spatial filtering effect, yielding a direct correlation between the frequency content of the transmitted or received signals and the direction of propagation. The proposed transducer is designed to actuate or sense the A0 Lamb wave propagating in three orientations using varying frequencies and has three channels with distinct frequencies for each direction, ranging from 50 to 450 kHz. The transducer performance was verified through finite element (FE) simulations, accompanied by experimental testing using a scanning laser Doppler vibrometer (SLDV). The unique frequency-steering capability of FSATs is combined with the ON-OFF keying (OOK) modulation scheme to achieve frequency directivity in hardware, similar to ongoing research in 5G communications. The multiple-in-multiple-out (MIMO) capabilities of the transducer were finally tested over a thin aluminum plate, showing excellent agreement with the FE simulation results.
本文介绍了一种基于导波（GWs）的新型定向换能器，其设计用于结构健康监测（SHM）和声数据通信应用，即在弹性介质作为传输通道且信息通过弹性波在介质中传输的系统。此类系统可以克服与传统通信方法（如基于有线或射频（RF）的方法）相关的困难，传统方法可能很复杂，并且在恶劣环境或难以到达的地方存在局限性。然而，这些技术的发展受到导波色散和多模传播以及多径干扰的阻碍。通过采用频率可控声学换能器（FSAT）可以有效解决这些缺点，FSAT利用其固有的定向能力。这可以通过利用频率相关的空间滤波效应来实现，从而在发射或接收信号的频率成分与传播方向之间产生直接关联。所提出的换能器设计为使用不同频率来激励或感测在三个方向上传播的A0兰姆波，并且每个方向具有三个不同频率的通道，频率范围从50 kHz到450 kHz。通过有限元（FE）模拟验证了换能器的性能，并使用扫描激光多普勒测振仪（SLDV）进行了实验测试。FSAT独特的频率转向能力与开关键控（OOK）调制方案相结合，以在硬件中实现频率指向性，类似于5G通信中的正在进行的研究。最后在薄铝板上测试了换能器的多输入多输出（MIMO）能力，结果与FE模拟结果显示出极好的一致性。
