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Research On Transmission Characteristics And Structural Damage Detection Method Based On Ultrasonic Guided Wave

Posted on:2024-03-08Degree:MasterType:Thesis
Country:ChinaCandidate:Z J XuFull Text:PDF
GTID:2531307094957209Subject:Circuits and Systems
Abstract/Summary:PDF Full Text Request
Oil and gas storage and transportation,aerospace engineering,transportation and other fields are widely used metal structures,such as pipelines,thin plates,rails and many other structural forms.Due to the influence o f manufacturing process and service environment,the overall performance of metal structures will be continuously reduced over time and may be damaged in extreme cases,bringing catastrophic consequences.Damage detection and structural health monitoring of structural systems,mastering their health conditions and diagnosing damage information in a timely manner are of great importance to ensure structural safety and avoid major accidents.For ultrasonic guided wave in rail detection by the dispersion effect and transmission medium and other factors,resulting in the received signal to noise ratio and distance resolution degradation problem.The Barker coding excitation technique is used in ultrasonic guided wave rail detection.The effects of square pulse,sinusoidal pulse,Hanning window modulated sinusoidal pulse and the number of carrier periods on the pulse compression results of Barker coded excitation are compared by simulation.It is shown that the 10-period carrier wave has the widest main flap width with a peak partials ratio of about-24.0d B.Experimental verification is carried out by field tests.The results show that the peak partials level of the Barker coded excitation ultrasonic waveguide signal is-14.40 d B after pulse compression,which is 3.26 d B higher than that of the single pulse excitation signal,and the results indicate the reliability of ultrasonic waveguide transmission in the steel rail environment using the coded excitation technique.Aiming at the problem that it is difficult to identify and locate the nonlinear ultrasonic guide wave signals with coding characteristics in the steel rail environment,a multi-cascade sliding filter adaptive peak detection method based on derivative transformation is proposed.Firstly,the coded exci tation ultrasonic guide wave signal characteristics are analyzed,signal preprocessing is performed using pulse compression,and the mutual correlation function is calculated.Secondly,considering the effects of peak parametrization level,multipath effect and noise,the cascaded sliding filter and Hilbert transform are used to reduce the parametrization and extract the envelope.Finally,the peak position of the correlation sequence is detected according to the derivative transform.The experiments show that the algorithm can effectively extract the peak information,has good anti-noise effect,has good recognition ability in complex track environment and the accuracy of the algorithm reaches 94.34%,which is suitable for coded excitation ultrasonic transmission system and easy to be implemented in real-time detection system.The ultrasonic transmission processes and damage detection in metallic structures were investigated experimentally.In the finite element simulations,the signal mechanism is analyzed according to the nonlinear interaction of different ultrasonic guided wave excitation signals with the metal structure and how to locate the damage signal is illustrated.The defect information in the pipeline was further examined by experimental methods.The experimental results found that the UGW signal with excitation characteristics is very sensitive to the damaged structure.Finite element analysis and excitation signals can be used as a potential method for quantitative assessment of defects in metal components.The results of this study provide a basis for modeling and simulation using finite elements in the field of nondestructive testing and structural health monitoring.
Keywords/Search Tags:Ultrasonic guided wave, Coded excitation, Pulse compression, Adaptive peak detection, Finite element analysis method
PDF Full Text Request
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