Research On Damage Monitoring Methods Of Typical Engineering Structures Based On Ultrasonic Guided Waves

In recent years,accidents caused by the damage of engineering structures emerge in an endless stream.The safety and reliability of engineering structures have become the focus of social.At the same time,structural health monitoring technology is developing constantly.Among various damage monitoring technologies,the theory and technology of ultrasonic guided waves have become frequently-used.This technology involves mathematics,mechanics,simulation testing,sensor technology,signal processing technology and so on.It is a comprehensive technology of multi-disciplinary integration.Most structures in practical engineering are composed or derived from plate structure and pipe structure.This paper takes common industrial metal structure such as aviation aluminum plate and oil pipeline as the research object,the detailed contents are as follows:The technology of structure health monitoring based on ultrasonic guided wave was briefed introduced in this paper.Combined with the dispersion curve,the multi-model and dispersion characteristics generated in the propagation are analyzed.Aiming at the damage signal received by the responder,the damage time information extraction and damage location method are studied.As for the common plate structure in engineering,various factors affecting the center frequency of excitation are considered comprehensively to optimize the excitation signal,such as ultrasonic guided wave mode,time domain resolution,excitation signal amplitude,and energy loss in propagation process.Aiming at the actual situation of large-scale sensor arrangement in engineering,the reasons of the leakage judgment and misjudgment of the traditional damage identification method under the limited number of sensor arrays are specifically analyzed,a damage identification and location imaging method based on relative distance are studied and designed.Finally,single damage and multi-damage experiments are carried out to verify and analyze the experimental error for the central area,boundary area and stiffened area of plate structure.According to the characteristics of the pipe and the propagation of the guided wave in it,the mode of the guided wave,the guided wave structure and the transmission energy leakage,the similarity of ultrasonic guided wave mode,and the single-point excitation mode are analyzed.The appropriate guided wave excitation signal is selected.The influence of multimode characteristics and multi-path effects on damage identification and location imaging is analyzed,and a localization imaging method based on sub-region excitation detection are studied and designed.Finally,experimental verification and error analysis are carried out in single and multi-damage states respectively.For the requirement of integration and intellectualization of equipment in engineering,the method of system integration is studied.The hardware is mainly composed of damage assessment module,active excitation module,high-speed acquisition module,power supply and heat dissipation module.The control of the whole system as well as the identification and imaging of the damage are realized in the environment of LabVIEW and MATLAB.Finally,the system function is verified in experiments.