弯管中超声导波传播特性的研究

Research on the Propagation Characteristics of Utrasonic Guided Waves in Curved Pippes

为了利用超声导波检测弯管中的缺陷,研究了L(0,2)模态在弯管中的传播特性．通过实验得到了不同曲率半径的90°弯管中L(0,2)模态的透射系数．结果表明,L(0,2)模态在弯管中传播时会出现模态转换现象,幅度有相应的衰减,从而影响导波的传播距离和缺陷检测能力;随着曲率半径的增大,L(0,2)模态的透射系数逐渐越小,并且对于同一弯管,激励频率越大,透射系数也越小．

The propagation characteristics of L （0, 2） mode in curved pipes are investigated theoretically and experimentally for the purpose of defect detection in curved pipes by using ultrasonic guided wave. With experiments, transmission coefficients of L （0, 2） mode in 90° curved pipes with different curvature radii are tested. Results show that mode conversion phenomena happen and their amplitude attenuates consequently when L （0, 2） mode propagates in curved pipes, and propagation distance and capability of defect detection are effected. Furthermore, transmission coefficients of L （0, 2） mode decrease while curvature radii increase. When excitation frequencies increase in the same curved pipe, transmission coefficients decrease.