Quantitative Ultrasonic Detection And Evaluation Of Impact Damage In Carbon Fiber Composites

Carbon fiber composites have a wide range of applications in industrial manufacturing sectors such as aerospace,automotive and rail due to their unique lightweight and high strength properties.However,carbon fiber composites are subject to impact damage during manufacture,transport and use,which can lead to a reduction in their mechanical and serviceability properties.It is therefore essential to test and evaluate the impact damage of carbon fiber composites.Traditionally,the impact damage of carbon fiber composites assessed by destructive testing,which can achieve certain objectives but is inefficient and consuming,so non-destructive testing methods and techniques need to be developed.Ultrasonic inspection technology is suitable for non-destructive testing of impact damage to carbon fiber composites due to its ease of use,speed and safety,and has significant research value.This paper developed an ultrasonic impact testing equipment for carbon fiber composites.The system enables automatic non-destructive testing of impact damage to carbon fiber composites,automatic processing and analysis of test data,automatic generation of ultrasonic C-scan images of impact damage to carbon fiber composites,and quantitative testing of the quality of impact damage to carbon fiber composites.Developed a carbon fiber composite impact tester to produce impact damage specimens with a precise impact energy of 0-30 J.The tester has a compact mechanical structure,small size,and precise control of impact energy input.The impact platform is compact,small in size,and can precisely control the impact energy input,which provides a good test basis for ultrasonic quantification and non-destructive testing of impact damage to carbon fiber composite laminates.Used a numerical ultrasonic simulation to detect the impact damage of carbon fiber composites using finite element analysis,and investigated the ultrasonic wave propagation law of ultrasonic incident from different areas of carbon fiber composites.The study showed that the amplitude intensity of the ultrasonic primary echo changes with the movement of the ultrasonic probe on the surface of the carbon fiber composite.This study provided a theoretical basis for the selection of the ultrasonic primary echo intensity of carbon fiber composites as a characteristic value of defects.Used ultrasound to inspect the impact damaged area of the carbon fiber composite and acquire the ultrasonic A-wave signals so that perform time domain and frequency domain analysis.The standard deviation of the analysis results of time domain from the actual measurements was 0.32 with a mean of 0.15 and the standard deviation of the analysis results of frequency domain from the actual measurements was 0.73 with a mean of 0.21.The results showed that the ultrasonic time domain signal is more accurate for measuring the length of defects on the sweep line of impact damage of carbon fiber composites.After extracting different eigenvalues of the ultrasonic A-wave signal,generate ultrasonic C-scan images of the impact damage of carbon fiber composites.The results showed that the intensity of the ultrasonic primary echoes in the ultrasonic A-wave signal could accurately characterize the impact damage defects in carbon fiber composites.In addition,applied filtered the generated ultrasonic C-scan images and C-scan images edge optimization algorithms to reveal better image pixels and clearer edge features,and extracted the defect area of the carbon fiber composites by computer algorithms.On this basis,performed a tensile test on the impact-damaged specimens of carbon fiber composites,and the tensile strength of the specimens is fitted to the defect area to obtain the relationship between the defect area and the tensile strength of the specimens,thus realizing systematic non-destructive testing and quantitative assessment of the impact-damaged quality of carbon fiber composites.