De Cicco Giorgio, Morten Bruno
Department of Physics, CNISM, University of Modena and Reggio Emilia, Modena, Italy.
Ultrasonics. 2008 Dec;48(8):697-706. doi: 10.1016/j.ultras.2008.03.012. Epub 2008 Apr 7.
A method is presented for exciting the propagation of plate waves in elastic guides. It is implemented in a device whose minimum working structure consists of a non-piezoelectric plane guide and two piezoelectric transducers operating as a generator and detector. The device is entirely in accordance with thick-film technology standard procedures. Both transducers are composed of a PZT ferroelectric layer deposited on a ceramic substrate and a suitable system of three coplanar metal electrodes placed inside the same layer. Beside setting the wavelength of propagation, the electrode system promotes piezoelectric deformations parallel to the substrate simultaneously contracting and extending contiguous active regions in the layer. Pure shear stresses are then induced on the involved guide surface, alternately distributed, with the spatial periodicity of the wave that will propagate in the guide. The propagation of several kinds of guided waves is possible so the selection of the one that meets a specific device design best is allowed. This work describes the design, realization and operation of a prototype structure consisting of an alumina plate guide and two pairs of piezoelectric thick-film transducers realized on it. The results related to the propagation of symmetric and asymmetric Lamb modes are reported. Moreover, the potential of the method is highlighted, emphasizing its effectiveness, easy implementation and application in the development of devices for the sensing and non-destructive testing areas.
本文提出了一种激发弹性波导中板波传播的方法。该方法在一种装置中得以实现，其最小工作结构由一个非压电平面波导和两个用作发生器和探测器的压电换能器组成。该装置完全符合厚膜技术标准流程。两个换能器均由沉积在陶瓷基板上的PZT铁电层以及置于同一层内的合适的共面三金属电极系统组成。除了设定传播波长外，电极系统还能促使平行于基板的压电变形，同时使该层中相邻的有源区域收缩和伸展。然后，在相关波导表面会产生纯剪应力，其交替分布，具有将在波导中传播的波的空间周期性。几种导波的传播都是可能的，因此可以选择最符合特定器件设计的那种导波。本文描述了一个原型结构的设计、实现和操作，该结构由一个氧化铝板波导以及在其上实现的两对压电厚膜换能器组成。报告了与对称和非对称兰姆波传播相关的结果。此外，强调了该方法的潜力，突出了其在传感和无损检测领域器件开发中的有效性、易于实现和应用。
