Development of Focus-type Ultrasonic Spectroscopy System Using Polymeric Piezoelectric Films

本计画的目的是发展一套能侦测不同材料局部声学特性的超音波光谱系统，并将其应用于无损检测。通过近两年的研究，取得了如下成果：1）利用聚合物压电薄膜，结合单脉冲和快速傅里叶变换方法，成功地构建了超声光谱系统，它能在较宽的频率范围内快速测量声速和吸收。通过在由脉冲马达驱动的X-Y-Z样品台之外使用聚合物超声波换能器或具有凹形形状的声透镜，三维超声光谱测量成为可能。该系统已成功地应用于观察各种聚合物如Nylom-6和聚合物液晶中的机械松弛，揭示了频率依赖性。4）该系统在玻璃/聚合物复合材料给出了所包含的玻璃珠的直径和分散性的信息。5）该系统提供有价值的信息的能力，这不能通过常规的超声测量获得，对金属、复合材料和生物材料的内部结构和力学特性的研究，提出了一种实用的方法。

Objectives of this project are to develop the ultrasonic spectroscopy system capable to investigate local acoustic characteristics of various materials and to apply the system for nondestractive testings. By performing the research in these two years, the foolowing good results have been obtained.1) By utilizing polymeric piezoelectric films and combining the single pulse and fast Fourie transformation method, we succeeded in constructing the ultrasonic spectroscopy system, which can perform rapidly measurements of ultrasonic velocity and absorption in a wide freauency range.2) By using a polymeric ultrasonic transducer or an acoustic lens with a concabe shape in addition to the X-Y-Z sample stage driven with a pulse motor, three-dimensional ultrasonic spectroscopy mesurements have become possible.3) The system was successfully applied to observe mechanical ralaxations in various polymers such as Nylom-6 and polymer liquid crystals, revealing the frequency dependent natures.4) The application of the system to glass/polymer composites gave the information of diameters and dispersity of the included glass beads.5) The capability that this system provides valuable information, which can not be obtained by conventional ultrasonic measurements, on the internal structure and mechanical cararcteristics of metals, composites, and biomaterials is suggested, and a practical version of this instrument is now considered.