Measurement of dispersion curve of flexural mode guided wave at low frequency in pipeline

Pipes bending at low frequency can be considered as bending beams, and thus the classic beam theory can be used to calculate the theoretical dispersion curves. By measuring the vibration along the pipe at three equally spaced locations, the dispersion curve of the flexural mode in pipes is extracted. It is also found that larger spaces show better performance. The experimental dispersion curve fits well at the low frequency, but shows a big deviation at high frequency, indicating that the classic beam theory validates at low frequency.