Banks Robert, O'Leary Richard L, Hayward Gordon
Thornton Tomasetti, 19200 Stevens Creek Blvd, Ste 100, Cupertino, CA 95014, United States.
Centre for Ultrasonic Engineering, University of Strathclyde, Glasgow, Scotland G1 1XW, United Kingdom.
Ultrasonics. 2017 Mar;75:132-144. doi: 10.1016/j.ultras.2016.10.007. Epub 2016 Oct 19.
This paper details the development of a novel method for increasing the operational bandwidth of piezocomposites without the need for lossy backing material, the aim being to increase fractional bandwith by geometrical design. Removing the need for lossy backing materials, should in turn increase the transmit efficiency in the desired direction of propagation. Finite element analysis has been employed to determine the mode of operation of the new piezocomposite devices and shows good correlation with that derived experimentally. Through a series of practical and analytical methods it has been shown that additional thickness mode resonances can be introduced into the structure by a simple machining process. The shaped composites described in this paper offer increased operational bandwidth. A simple example of a two step thickness design is described to validate and illustrate the principle. A more complex conical design is presented that illustrates a possible tenfold increase in bandwidth from 30kHz to 300kHz, operating in air without backing. An illustration of the applicability of this type of transducer technology for frequency agile guided mode non-destructive evaluation is then presented.
本文详细介绍了一种新型方法的开发，该方法可在无需有损背衬材料的情况下增加压电复合材料的工作带宽，目的是通过几何设计提高分数带宽。去除对有损背衬材料的需求，相应地应能提高在所需传播方向上的发射效率。已采用有限元分析来确定新型压电复合材料器件的工作模式，结果表明其与实验得出的结果具有良好的相关性。通过一系列实践和分析方法表明，可通过简单的加工工艺在结构中引入额外的厚度模式共振。本文所述的成形复合材料具有更大的工作带宽。描述了一个两步厚度设计的简单示例，以验证和说明该原理。还给出了一个更复杂的锥形设计，该设计表明在无背衬的空气中工作时，带宽可能从30kHz增加到300kHz，增加了十倍。随后展示了这种类型的换能器技术在频率捷变导模无损检测中的适用性。
