Kim Yoon Young, Park Chan Il, Cho Seung Hyun, Han Soon Woo
School of Mechanical and Aerospace Engineering and National Creative Research Initiatives Center for Multiscale Design, Seoul National University, Shinlim-Dong, San 56-1, Kwanak-Gu Seoul 151-742, Korea.
J Acoust Soc Am. 2005 Jun;117(6):3459-68. doi: 10.1121/1.1904304.
For the efficient long-range nondestructive structural health inspection of pipes, guided waves have become widely used. Among the various guided wave modes, the torsional wave is most preferred since its first branch is nondispersive. Our objective in this work is to develop a new magnetostrictive transducer configuration to transmit and receive torsional waves in cylindrical waveguides. The conventional magnetostrictive transducer for the generation and measurement of torsional waves consists of solenoid coils and a nickel strip bonded circumferentially to test pipes. The strip must be premagnetized by a permanent magnet before actual measurements. Because of the premagnetization, the transducer is not suitable for the long-term on-line monitoring of pipes buried underground. To avoid the cumbersome premagnetization and to improve the transduction efficiency, we propose a new transducer configuration using several pieces of nickel strips installed at 45 degrees with respect to the pipe axis. If a static bias magnetic field is also applied, the transducer output can be substantially increased. Several experiments were conducted to study the performance of the proposed transducer configuration. The proposed transducer configuration was also applied for damage detection in an aluminum pipe.
为了对管道进行高效的远程无损结构健康检测，导波已得到广泛应用。在各种导波模式中，扭转波是最受青睐的，因为其第一分支是非色散的。我们这项工作的目标是开发一种新的磁致伸缩换能器配置，用于在圆柱形波导中发射和接收扭转波。用于产生和测量扭转波的传统磁致伸缩换能器由螺线管线圈和周向粘结在测试管道上的镍带组成。在实际测量之前，镍带必须用永磁体进行预磁化。由于预磁化，该换能器不适用于地下埋设管道的长期在线监测。为了避免繁琐的预磁化并提高转换效率，我们提出了一种新的换能器配置，使用几片相对于管道轴线成45度角安装的镍带。如果还施加静态偏置磁场，则换能器输出可大幅增加。进行了多项实验来研究所提出的换能器配置的性能。所提出的换能器配置也应用于铝管的损伤检测。
