The scattering of the fundamental torsional mode from axi-symmetric defects with varying depth profile in pipes
The scattering of the fundamental torsional mode from axi-symmetric defects with varying depth profile in pipes
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DOI：
10.1121/1.3373406
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发表时间：
2010-06-01
影响因子：
2.4
通讯作者：
Cawley, P.
中科院分区：
文献类型：
--
作者：
Carandente, R.;Ma, J.;Cawley, P.
导波已被成功地应用于检测钢板和管道中的缺陷和腐蚀；然而，由于实际中遇到的缺陷的复杂轮廓，缺陷大小的确定仍然具有挑战性。通过有限元模拟和实验验证，研究了变深度轴对称缺陷对扭转基模T(0，1)的反射。渐变深度的缺陷由一系列锥形台阶表示。结果表明，对于锥形上台阶和下台阶，波包只在台阶的开始和结束处被反射。预测了阶跃开始和结束时的反射，研究了阶跃总反射的频率依赖性。研究表明，由于缺陷两端反射波之间的干涉，反射系数随缺陷平均长度与波长之比的变化而变化。反射系数最大值随着锥形斜率变得更加平缓而减小，这种影响随着平均缺陷长度与波长之比的增大而更加明显。(C)2010年美国声学学会。[DOI：10.1121/1.3373406]
Guided ultrasonic waves have been successfully applied to detect defects and corrosion in plates and pipes; however, defect sizing remains challenging due to the complex profiles of the defects encountered in practice. A study of the reflection of the fundamental torsional mode T(0,1) from an axi-symmetric defect with varying depth profile has been carried out via finite element modeling and experimental validation. Defects with gradually varying depth are represented by a series of tapered steps. It is revealed that, for both tapered up- and down-steps, the wave packet is reflected only at the start and end of the steps. The reflections from the start and end of the step have been predicted, and the frequency dependence of the overall reflection from the step has been studied. The study shows that the reflection coefficient varies as a function of the ratio of the average length of the tapered defect to the wavelength due to the interference between the waves reflected from the two ends of the defect. The reflection coefficient maxima decrease as the slope of the taper becomes more gradual, this effect being more pronounced when the ratio of the average defect length to the wavelength increases. (C) 2010 Acoustical Society of America. [DOI: 10.1121/1.3373406]