Research On Ultrasonic Detection And Signal Processing Technology Of GFRP Layered Defects

Because composite materials have the characteristics of light weight,high strength,convenient processing and forming,excellent elasticity,chemical corrosion resistance and good weather resistance,they have gradually replaced wood and metal alloys and are widely used in aerospace,automotive,electronic and electrical,construction and other fields.In recent years,it has developed rapidly.With the advancement of technology and structural requirements,the structure of glass fiber composite materials also shows a trend of complexity and integration.Due to the characteristics and process requirements of glass fiber composite materials,defects such as pores,delamination,resin richness,and fiber bending are easy to form during the molding process.These defects greatly affect the performance of the composite structure.Therefore,non-destructive testing of internal defects of glass fiber composite materials is also particularly important.In recent years,as composite materials have become more and more widely used,it has also become a research hotspot.Ultrasonic technology is one of the commonly used methods for detecting internal defects of materials,but due to the particularity of the structure of glass fiber composite materials,the echo signal is complicated and the features are not easy to extract.Aiming at the characteristics of complex components and high noise in ultrasonic detection of glass fiber composites,a signal processing method based on variational mode decomposition was studied in this paper.Particle swarm optimization was used to optimize the parameters,which improved the signal to noise ratio of the echo signal.Based on the nonlinear theory of ultrasonic propagation of glass composites,a recursive graph model of internal defects of glass fiber composites was established.The applicability and difference of the recursive quantitative parameters were analyzed,and the defect identification method of the recursive quantitative analysis model was studied with the recursive rate,certainty rate and stratification as the input.Through sample data,it is verified that the ultrasonic defect signal of glass fiber composites can be identified by recursive graph analysis technique.