Optimization and system design of piezoelectric ultrasonic SH guided wave method in pipeline wall thickness measurement
In order to investigate the propagation characteristics of shear horizontal(SH)waves in a bounded plate,the study started from the basic theory of SH waves.According to the non-dispersive characteristics of SH0 wave propagating in an infinite plate simulation analysis and experimental verification of the propagation characteristics of SH0 waves in a bounded plate structure were carried out.The results show that the SH0 wave propagating in the bounded plate structure can maintain excellent non-dispersive characteristics under the excitation condition of 3.0 MHz·mm.On this basis,a set of pipeline wall thickness measuring device based on piezoelectric ultrasonic SH0 guided wave is designed,aiming at the common problems such as coupling difficulty and chaotic echo signal in the study of thickness measurement using SH guided wave.The experimental results show that the designed coupling device of"pre-fixed"and"secondary fixed"can effectively solve the cou-pling problems.Based on the device,a calculation method of pipe wall thickness ignoring the first echo signal is proposed,which can accurately calculate the wall thickness from the original echo signal and keep the error between the measured value and the real value within 0.05 mm.The research method proposed in this paper provides a new solution for pipeline thickness detection and on-line monitoring of industrial pipelines,and has important reference value and guiding significance in engineering field.
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