【摘要】 简述了空心圆管中超声导波的基本理论,用有限元程序AN SY S对管道超声纵向导波裂纹检测进行了数值模拟.管道模型中,以删除单元模拟管道周向裂纹,通过对管道一端端部周向各节点施加经H ann ing窗调制的10周期纵向单音频叠加信号,模拟纵向入射应力波,同端接收反射应力波,对含单、双裂纹的管道模型进行了数值模拟,通过裂纹反射波到达时间,可准确地判断出单、双裂纹所在位置,并对模拟结果进行了频谱分析,频域信号显示出管道中存在裂纹时幅值和频率成分的显著变化.更多还原

【Abstract】 After a description of the basic theory on ultrasonic guided wave in hollow pipes,a numeric simulation has been made on pipe cracks using ultrasonic longitudinal guided wave by using finite element code ANSYS.Pipe cracks are defined by the method of removing elements.Ten cycles of narrow-band signal modulated by Hanning window are chosen for excitation,and are simulated by prescribing axial transient displacement at one end of pipe model.The echo can be received at the same end.The position of single and double cracks could be approximately determined by the reverse time of the reflection.The spectrum analyses show that marked changes in amplitude and frequency components can be observed when there are pipe cracks.更多还原