CFRP层板缺陷与铺层方向的红外热波雷达成像检测技术研究

发布时间：2018-11-10 11:39

【摘要】：碳纤维增强复合材料(Carbon Fiber Reinforced Polymer,CFRP)具有高比强度、高比模量、疲劳特性好等优良性能,已广泛应用于航空、航天、石油化工、汽车、风力发电及军事工业等领域。CFRP层板在成型与使用过程中,受成型工艺与工作环境的影响,易产生孔隙、冲击损伤、纤维断裂、分层、脱粘等缺陷,人工铺层CFRP层板容易出现纤维层错铺等问题。CFRP层板缺陷或纤维层铺错将严重影响CFRP层板制件的使用性能及寿命,在生产过程中迫切需要简单、有效、快速的无损检测方法或技术实现对CFRP层板缺陷与铺层方向的可靠检测。红外热波雷达成像检测技术将红外热波成像检测与雷达探测技术相结合,可有效提高热波信号的带宽和信噪比,具有抗干扰能力强、检测范围大、检测灵敏度高等优势,为CFRP层板缺陷与铺层方向检测提供了一种新方法,因此,本文对CFRP层板缺陷与铺层方向的红外热波雷达成像检测技术开展了系统深入的研究。研究了线性调频(Chirp调制)面热流作用CFRP层板的热传递过程及温度场分布,通过数值仿真分析确定了热波雷达信号的时频域响应特征,并提出了基于希尔伯特变换瞬时特性时域积分与双路Chirp锁相相关的热波雷达信号特征提取算法。分析了检测参数与缺陷几何特征对热波雷达信号特征的影响与规律;探讨了红外热波雷达成像检测铺层方向的可行性,仿真分析了检测参数与铺层方向对热波雷达信号特征分布的影响与规律,为开展相关试验研究工作提供理论基础。搭建了调制激光激励的红外热波雷达成像检测系统,实现了对CFRP层板缺陷与铺层方向的高效、可靠检测。通过检测试验,研究了检测参数、缺陷几何特征与铺层方向对热波雷达信号响应特征的影响规律,分析了各种特征提取算法(相关算法、瞬时特性时域积分与双路Chirp锁相相关)的优势,验证了仿真分析结果的正确性,确定了合理的检测参数范围。依据无损检测POD(Probability of Detection)分析理论与方法,对红外热波雷达成像检测CFRP层板缺陷的POD水平开展了相关研究工作。提出了红外热波雷达成像无损检测技术的缺陷判定准则,分析了检测参数、特征提取算法对POD水平的影响规律,获得了不同缺陷判定阈值下,红外热波雷达成像检测CFRP层板缺陷的POD数据,为红外热波雷达成像检测技术的工程应用提供了有力依据。开展了红外热波雷达成像检测CFRP层板缺陷与铺层方向的识别方法研究,提出了基于有限元模型修正与数值优化技术的CFRP层板缺陷与铺层方向的识别方法。采用基于模拟退火算法与Nelder-Mead算法的混合算法实现了CFRP层板缺陷直径与深度的识别,对于直径在8~12mm,深度在0.6~2.0mm范围内的模拟层板缺陷,直径与深度的预测误差均小于6%;探讨了所提出的识别方法检测铺层方向的可行性,研究表明该方法可实现7层CFRP层板铺层方向的识别,铺层角度最大预测误差小于6°。
[Abstract]:Carbon fiber reinforced composite (Carbon Fiber Reinforced Polymer,CFRP) has been widely used in aeronautics, aerospace, petrochemical, automobile and so on for its excellent properties such as high specific strength, high specific modulus and good fatigue properties. Wind power generation and military industry. In the process of forming and using CFRP laminate, it is easy to produce porosity, impact damage, fiber fracture, delamination, debonding and other defects due to the influence of molding process and working environment. The defects of CFRP laminates or fiber laminates will seriously affect the performance and service life of CFRP laminates, and it is urgent to be simple and effective in the process of production. Fast nondestructive testing method or technique can detect the defect and laying direction of CFRP laminate reliably. Infrared thermal wave radar imaging detection technology combines infrared thermal wave imaging detection with radar detection technology, which can effectively improve the bandwidth and signal-to-noise ratio of the thermal wave signal. It has the advantages of strong anti-jamming ability, large detection range and high detection sensitivity. This paper provides a new method for the detection of defects and orientation of CFRP laminates. Therefore, the infrared thermal wave radar imaging detection technology of CFRP laminate defects and laminates is studied systematically and deeply in this paper. The heat transfer process and temperature field distribution of the CFRP laminate subjected to the heat flux on the linear frequency modulation (Chirp) surface are studied. The time-frequency response characteristics of the thermal wave radar signal are determined by numerical simulation. Based on Hilbert transform, a feature extraction algorithm of heat wave radar signal is proposed, which is based on the temporal integral of Hilbert transform and dual Chirp phase locking. The influence and regularity of detection parameters and defect geometry on the characteristics of heat wave radar signal are analyzed. In this paper, the feasibility of infrared thermal wave radar imaging is discussed. The influence of detection parameters and layer orientation on the characteristic distribution of thermal wave radar signal is simulated and analyzed, which provides a theoretical basis for the related experimental research. An infrared thermal wave radar imaging detection system with modulated laser excitation is set up to detect the defects and layering direction of CFRP laminates with high efficiency and reliability. In this paper, the influence of detection parameters, defect geometry features and layering directions on the response characteristics of thermal wave radar signals is studied through testing experiments. Various feature extraction algorithms (correlation algorithms) are analyzed. The advantage of time-domain integral of instantaneous characteristics is related to two-channel Chirp phase locking), which verifies the correctness of the simulation results and determines the reasonable range of detection parameters. Based on the theory and method of nondestructive testing (POD (Probability of Detection), the POD level of infrared thermal wave radar imaging for detecting defects in CFRP laminates is studied. The defect determination criterion of infrared thermal wave radar imaging nondestructive testing technology is proposed. The influence of detection parameters and feature extraction algorithm on POD level is analyzed. The POD data of infrared thermal wave radar imaging for detecting defects in CFRP laminate provide a powerful basis for the engineering application of infrared thermal wave radar imaging detection technology. In this paper, the identification method of CFRP laminate defects and layering directions by infrared thermal wave radar imaging is studied, and a method based on finite element model correction and numerical optimization is proposed to identify the CFRP laminate defects and orientation. A hybrid algorithm based on simulated annealing algorithm and Nelder-Mead algorithm is used to identify the defect diameter and depth of CFRP laminates. The prediction errors of diameter and depth are less than 6. The feasibility of detecting the orientation of CFRP laminates by the proposed method is discussed. The results show that this method can recognize the orientation of seven layers of CFRP laminates, and the maximum prediction error of laying angle is less than 6 掳.
【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TN957.52

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