Study On The Method And System Of Air Coupled Ultrasonic Imaging For Fiber Reinforced Composite

Fiber reinforced composite materials are widely used in the aerospace industry due to their excellent mechanical properties.However,cracks,laminations,and other defects are inevitably generated during the production and service of composite materials,which affects the stability and safety of the system.Air-coupled ultrasound broke through the limitations of coupling agents during the testing process,and achieved non-destructive testing of materials under non-contact conditions,which meets the requirement that certain materials do not use coupling agent detection,so it is important for ensuring production quality and system safety.This article has completed a composite scanning imaging detection system based on air-coupled ultrasound and developed the corresponding imaging detection software.The research results have certain practical value for the quality inspection and maintenance inspection of composite materials.This paper has discussed the principles of air-coupled ultrasonic testing,the finite element simulation of air-coupled ultrasonic testing,the development of system and imaging detection software and the one-dimensional signal processing algorithm and image enhancement processing algorithm.Firstly,the principle of ultrasonic testing and the current research status of air-coupled ultrasonic technology at home and abroad are discussed.The law of the interaction between acoustic waves and materials and the transfer law of energy in the medium and its interface are analyzed.Then based on the finite element theory,COMSOL software was used to simulate the air-coupled ultrasonic testing of composite materials,and the detection results under different conditions were analyzed.The second is the design method of the whole imaging detection system.The system structure and the function of each module are discussed in detail.The feasibility of the entire system is verified through experiments.Finally,the denoising method of ultrasonic one-dimensional signal is studied.The wavelet threshold denoising and adaptive filtering methods are analyzed in detail.The effects of different methods and different parameters of denoising are compared on the basis of SNR.For ultrasound detection imaging results,in this paper,an ultrasonic image quality evaluation standard is used to evaluate them.Under the guidance of this standard,image filtering and image enhancement are applied to improve the image quality,so that the defects are identified easily.