超声导波农田灌溉管道的缺陷检测技术研究

he working environment of farmland irrigation pipeline is relatively bad, and it is easy to occur corrosion and aging in the pipeline work, resulting in the leakage of pipeline and serious waste of water resources.Therefore, it has important theoretical and practical value for the defect detection of irrigation pipelines. In view of the characteristics of elbow pipe and straight pipe in farmland irrigation pipeline, By artificially increasing defects, The propagation of modal guided waves of L (0, 2) in straight pipe, bent pipe and defective state is numerically investigated by using the finite element software ABAQUS. Sinusoidal signal using Hanning window modulation in theform of force loading, to stimulate L (0,2) mode signal. The propagation characteristics of straight and bent pipes are compared, and the influence of defects on propagation characteristics and energy distribution is analyzed. The result shows: Under the excitation signal of 200kHz, when the L (0,2) mode propagates in a straight pipe, the mode transition does not occur, and the amplitude decreases uniformly with time. Spread in the bend, L (0, 2) modal straight part in bends without modal transformation, and through the defect and bending parts of the bending part, L (0, 2) mode conversion to other possible modes in the transmission, extend the amplitude increases with time uneven decrease. Most of the energy of the modal L (0, 2) is concentrated outside the curve and is rarely bent inside. It is helpful to detect the defects of irrigation pipeline.