| Ultrasonic guided wave technology has the advantages of long propagation distance and sensitivity to a variety of damages.It has been widely used in health monitoring of pipe networks and large plate structures.In recent years,structural joints have become hot spots for structural health testing due to non-integral molding and stress concentration.In the detection of hot spots,due to factors such as complex surface structure and concentration of measured points,the echo signal is susceptible to interference from system crosstalk signals,which affects the accuracy of signal analysis.Especially in the one-transmission and multiple-reception working mode,the crosstalk between adjacent channels is large,and even the phenomenon of signal saturation,distortion,and overlap occurs,which has a great impact on subsequent signal analysis,processing,and damage location.Therefore,this paper designs and implements a set of one-shot multi-receiving active super-accounting system for the long acquisition time of ultrasonic guided wave monitoring system in large-area structure applications,as well as the excitation and received signal crosstalk encountered in hot spot area monitoring and other applications The low crosstalk ultrasonic guided wave system is designed to solve the problem of excessive crosstalk in hot spot detection.The main work is summarized as follows:(1)From the perspective of overall design,for the application of ultrasonic guided wave damage monitoring technology in hotspot areas,the key technologies urgently to be solved in hotspot area monitoring are analyzed,and the basic design requirements of hardware and software in active ultrasonic guided wave monitoring system are summarized.On this basis,the hardware and software design architecture of a multitransmission active ultra-low crosstalk ultrasonic guided wave system is proposed.(2)In terms of hardware design,based on the overall architecture and performance requirements of a multi-transmission active ultrasonic guided wave monitoring system,the NI-PXI architecture is used,equipped with a signal generator board and an oscilloscope board,and the selection design is completed for system acquisition requirements.The function of excitation and acquisition of a multi-received guided wave signal is realized.Focus on designing core components such as matrix switching switches.First,based on the SPI control bus,an analog switching matrix and a lownoise charge amplifier circuit are designed to achieve any sensor as an excitation source,and any other four as a receiving source.Received ultrasonic guided wave system;Second,a two-stage attenuation circuit with an interlocking isolation structure is designed,and the excitation and reception signals are highly isolated,even under highvoltage excitation sources,ultra-low crosstalk reception signals can be obtained.At the same time,the self-designed low-noise multi-channel charge amplifier is integrated on the matrix switch to achieve higher integration and lower inter-board interference.(3)In software design,write a hardware driver,build a man-machine interface to issue instructions,realize the selection and switching of excitation and reception signals through the serial and parallel ports of the single-chip microcomputer,and complete the modeling of the structural board under test,sensor path planning,signal analysis and processing and Design and implementation of damage location algorithm.(4)Build an experimental platform for experimental verification.This article integrates the designed matrix switch and other components into the developed ultrasonic guided wave system.Through the experimental verification of the damage monitoring of the hot spot area of the composite material,the signal shows good stability and accuracy Sex.Compared with the signals collected by commercial ultrasonic guided waves,the signal of this system is obviously superior,and finally achieves a more accurate damage detection and positioning effect. |
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