超声导波在管道中传播的数值模拟

Numerical Simulation of Guided Ultrasonic Wave Transmitted in Pipe

为了研究超声导波在管道中的传播特性并从中选择适合于无损检测的导波模态,在弹性动力学理论基础上,分析了超声导波在管道中传播时存在多模态与频散特性;通过编程数值计算了超声导波在管中传播时的频散曲线和各模态沿管壁的位移分布;利用数值计算结果以及Fourier分解法,模拟了导波在管道中的传播现象,获得各个模态在传播一定距离后的时域波形.结果表明,在特定频率下,L(0,2)模态导波频散现象较小、传播速度最快,是管道缺陷无损检测的理想模态.数值模拟结果与理论分析相吻合,并且证明此种Fourier分解法可以有效地模拟管道中超声导波的传播特性.

In order to study the transmitting characteristics of ultrasonic guided wave in pipe and select the guided wave mode suitable for non-destructive testing(NDT), the authors analyse, on the basis of elastic dynamics theory, the characteristics of multimode and dispersion of guided wave transmitted in pipe. They calculate, through programming numeric value, the dispersion curve of guided wave and the displacement distribution of various mode of the wave along the wall of pipe. The calculated result of numeric value and Fourier decomposition method are used to simulate the transmitting of guided wave in pipe so that the time domain waveform of different mode of wave after transmitting a certain distance is obtained. The results show that at special frequency, L(0, 2) mode is the ideal mode of pipe defects NDT for less dispersion and fast transmitting of guided wave. Numeric simulation is consistent with theoretical analysis, and proves that the Fourier decomposition method can effectively simulate the transmitting characteristics of ultrasonic guided wave in pipe.