【作者】 张澎涛；

【导师】 曹军； 孙丽萍；

【作者基本信息】 东北林业大学 ， 控制理论与控制工程， 2006， 硕士

【摘要】 由于复合材料具有刚度大、强度高、重量轻的显著优点,使其广泛应用于航空、建筑、工业等众多领域,但是复合材料在制造和使用过程中不可避免的会产生各种缺陷以及损伤,因此对复合材料的无损检测成为国内外许多学者研究的热点。本文研究碳纤维复合材料分层损伤的超声波无损检测方法,并设计了相应的检测电路以及基于DSP的算法,实现了对碳纤维复合材料分层损伤的定量检测。 本文在研究超声回波法检测机理和数字信号处理理论的基础上,对复合材料分层损伤进行了数学分析,设计了一套以TMS320VC5410DSP(Digital Signal Processing)芯片为核心、包括超声波脉冲电路、信号预处理、A/D转换及采样、控制与显示电路在内的测试系统,用来对超声检测回波信号作实时分析处理,实现分层状态信息的提取以及识别。在系统硬件电路设计中多选用小封装,低功耗,抗干扰能力强的芯片,降低了系统成本,减小了系统的体积。 在此基础上,本文分别对回波脉冲信号的时域特征参量:能量、幅值、衰减系数和频域特征参量:频谱、频移变化等进行分析,分别制定了相关的实时信号处理算法,并相应地设计了16位定点DSP算法实现程序。 通过对各种检测算法的效果进行综合分析比较发现时域信号处理后的数据特征差别比较明显,但以能量参量处理效果最佳,相对于时域处理,频域处理受耦合状况等因素影响较小,处理结果稳定。本课题实现了对碳纤维复合材料分层损伤量化检测的目的。通过本课题的研究工作,得到了一些有实用价值的实验方法和实验数据,为进一步研究复合材料损伤的超声波检测奠定了一定的基础。更多还原

【Abstract】 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.更多还原