Implementation Of Signal Acquisition And Processing Method For Air-Coupled Ultrasonic Testing

Composite materials,with their comprehensive properties that cannot be matched by traditional materials,have been widely used in high-precision fields such as aviation,aerospace,national defense,and military industries.With the continuous development of composite material technology,during the manufacturing and use of composite materials,due to reasons such as raw material defects,improper use operations,and material aging,the expected strength of composite materials cannot be achieved,resulting in significant instability factors in overall structural performance.Ultrasonic testing technology can effectively detect material damage and has gradually been widely applied.However,traditional ultrasonic technology requires the use of liquid coupling agents for detection,which limits its scope of use.Air-coupled ultrasonic detection technology,which uses air as a coupling agent,has begun to receive widespread attention,but air-coupled ultrasonic detection equipment is very expensive both domestically and internationally and cannot be widely applied.Based on the above background,this paper studies air-coupled ultrasonic detection technology and establishes an air-coupled ultrasonic signal acquisition and transmission scheme with an FPGA chip as the core.Based on this,the hardware circuit component selection,hardware circuit design,and PCB design for the acquisition part are completed.At the same time,the logic program design for each functional module is completed based on the Verilog language,and program function simulation is completed using Model Sim software.Simultaneously,this paper uses Qt5.15 software to develop an air-coupled ultrasonic testing upper computer,which realizes the control of the FPGA part,completes the communication function with the hardware,and realizes real-time uploading of air-coupled ultrasonic testing data.At the same time,multiple group row averaging denoising and timefrequency domain transformation are performed on the collected ultrasonic wave signals,and based on this,time-domain imaging feature value extraction and frequency-domain imaging feature value extraction are completed,ultimately achieving the visualization of air-coupled ultrasonic testing data.Based on the completion of the air-coupled ultrasonic detection signal acquisition hardware and software design,this paper constructs an experimental platform and conducts defect detection experiments on carbon fiber composite materials.The experimental results show that the hardware part runs stably,and the upper computer imaging effect is good,proving the feasibility of the proposed scheme,providing some engineering ideas for air-coupled ultrasonic testing,and having certain practical value.