Department of Mechanical Engineering, Imperial College, Exhibition Road, London SW7 2AZ, United Kingdom.
J Acoust Soc Am. 2011 Apr;129(4):1869-80. doi: 10.1121/1.3543958.
Successful ultrasonic guided wave detection of flaws at support locations relies on the ability to distinguish between the reflection produced by a simple support on an undamaged pipe and the reflection produced by pipe flaws. Consequently, it is essential to know how the reflections produced by simple supports behave; very little work has so far been reported on this subject. Through finite element simulations and experiments, this study develops a systematic understanding of how ultrasonic guided waves propagating along a pipe, in particular the T(0, 1) mode, interact with simple supports. It is shown that, unlike the T(0, 1) mode in a free pipe, the torsional mode in a supported region has a cut-off frequency, below which it will not propagate; below this frequency the T(0, 1) reflection coefficient is large, and it quickly reduces beyond the cut-off.
成功地通过超声导波在支撑位置检测缺陷，依赖于区分无损管道上简单支撑产生的反射和管道缺陷产生的反射的能力。因此，了解简单支撑产生的反射的行为是至关重要的；到目前为止，关于这个主题的研究工作很少。通过有限元模拟和实验，本研究系统地了解了沿管道传播的超声导波，特别是 T(0,1)模式，如何与简单支撑相互作用。结果表明，与自由管道中的 T(0,1)模式不同，支撑区域中的扭转模式有一个截止频率，低于该频率它将不会传播；在这个频率以下，T(0,1)反射系数较大，并且在截止频率之后迅速减小。
