中文摘要：

利用超声导波技术,对管道的裂纹检测进行了研究,理论分析了扭转模态的传播特点。基于有限元模拟,分析了不同尺寸裂纹对T（0,1）模态传播的影响。为检测管道中裂纹的位置和尺寸,引入了综合聚焦成像算法。利用该算法,将接收到的反射波在管道不同位置（θ,z）处聚焦成像,并建立管道的成像分布I（θ,z）。成像结果直观地反映了裂纹的位置和尺寸。

英文摘要：

Using ultrasonic guided wave technique,the crack detection of pipe was studied.Theoretically,characteristics of torsional modes were analyzed.Based on finite element simulation,affections of cracks with different lengths on T（0,1） mode were analyzed.In order to quantify the location and size of cracks,a synthetic focusing method was employed.Using this method,the recorded backscattered wave signals were focused at different locations（θ,z）,and the imaging distribution I（θ,z） was developed.This imaging result reflects the size and location of crack clearly.