Research On Non-destructive Testing Of Delamination In Carbon Fiber Composites With Ultrasonic

Because of the remarkable merit of composites, such as great rigidity, high intensity, light weight, it has been widely applied in the domain of aviation, architecture and industry and so on. But the composite would be inevitablely damaged, also have lots of flaw in manufacture and using process. Therefore non-destructive detecting of composite has been the studing hotspot for many domestic and foreign scholars. This paper studied non-destructive detecting method of delamination in carbon fiber composites with ultrasonic, and has designed the corresponding detecting electric circuit as well as algorithm based on the DSP, achieved the objective that quantitative detection of delamination in carbon fiber composites.In this paper, based on studying the principle of ultrasonic echo method and the digital signal processing theory a TMS320VC5410-cored DSP detecting system was established through mathematical analyses of delamination in composites. The ultrasonic producing circuit, signal pretreatment circuit, A/D converter and sampling circuit, control and display circuit were also included in this system. The detecting system was used to analyze and process the ultrasonic reflected wave signal in real-time mode, then the information of delamination state was picked-up. In the hardware circuit system this paper choosed the chip which is provided with small encapsulation,a little power consumption and great anti-jamming capability, so reduced the cost of system and minished the system volume.The characteristic parameters of the reflected waves' energy, amplitude, attenuation coefficient in time field and the characteristic parameters of spectrum and frequency shift in frequency field were analyzed respectivelythe relative real-time signal disposing algorithms were also established accordingly, the corresponding 16-bit definite-point DSP arithmetic was also written.Through synthetical analyses and comparison to effect of each detecting method the paper discovered that the data disposed in time field was different distinctly, however effect of disposal for energy parameter was the best, relative to disposal in time field the disposed result in frequency field was more stable and less influenced by coupling and many other factors. The goal of quantificational detection of delamination in carbon fiber composites had been reached. Through the studying the work presented in this paper had received some practical experimental methods and data. In a certain extent it laid a foundation for further studying on ultrasonic detecting of damage and flaw in composites.