窄板中超声导波传播特性试验研究

针对工程中窄板结构安全评价问题，该文对窄条板结构中超声导波传播特性进行了试验研究。首先，对无限大板结构中不同模态超声导波的传播特性进行了理论分析。然后，在不同宽度窄铝板上进行了不同模态超声导波对比试验研究。结果表明，与兰姆波相比，低阶水平剪切波(SH0波)受窄板宽度方向边界的影响小。当窄板宽度大于电磁声换能器宽度情况下，SH0波检测结果不受板宽度变化影响。在此基础上，将SH0波应用于电力系统接地网扁钢检测。结果表明，SH0波在扁钢中传播能力强，可用于现地埋扁钢无损检测。该文研究工作为工程窄板结构健康检测提供可行的技术方案。

ON PROPAGATION CHARACTERISTICS OF GUIDED WAVES IN NARROWBAND

For the safety evaluation of narrowband used in engineering structures, the propagation characteristics of guided waves in a narrowband are investigated experimentally. Firstly, the characteristics of guided waves propagated in an infinite plate is theoretical analyzed; then the contrastive experiments are conducted in narrowbands with different widths using different modes of guided waves. It is found that comparing to the lamb modes, shear horizontal waves (SH0) are almost not affected by the boundary of a narrowband, and the width variation of a narrowband has no influence on the waveforms of an SH0 mode when the width of a narrowband is bigger than the width of electromagnetic acoustic transducers. Finally, the SH0 mode guided wave is used to the non-destructive testing (NDT) of flat steel in a ground grid. It is showed that a SH0 mode can propagate a long distance in flat steel, and can be used for NDT of buried flat steel. The developed method provides feasible scheme for the health monitoring of narrowbands in engineering structures.