基于超声LAMB波的碳纤维复合材料分层缺陷识别的研究

发布时间：2018-11-27 21:33

【摘要】：碳纤维复合材料的综合性能优越,因此被广泛地应用于各个领域当中。碳纤维复合材料在使用的过程中,因为材料本身的缺陷,或者一些由碳纤维复合材料制造而成的构件和设备在使用的过程中造成的材料的缺陷,都会给使用者带来安全隐患,甚至造成巨大的损失。因此材料缺陷的检测是尤其重要的一个环节。超声无损检测技术是目前比较先进的一种无损检测技术,而计算机层析成像技术更是被成熟广泛的应用于医学领域中。本文的主要内容是将超声无损检测技术与计算机层析成像技术相结合,用于碳纤维复合材料分层缺陷的检测识别。研究内容如下:通过查阅国内外文献资料,了解了超声波在各项同性和各向异性材料中的传播特性,并分别给出了超声兰姆在这两种不同材料介质中的频散方程和频散曲线。为在有限元仿真和实验中超声兰姆波激励信号和走时的提取提供了理论依据。详细地介绍了计算机层析成像技术的理论基础,并且推导出了基于中心切片定理的平行扫描滤波反投影算法和扇形扫描滤波反投影算法的数学公式,最后分别给出了这两种算法的详细步骤。通过对比,最终选择了扇形扫描滤波反投影算法对用于本文仿真和实验的图像重建算法。选择碳纤维复合材料多向板T300/5028作为本文的研究对象,利用ABAQUS有限元软件分别建立分层缺陷在不同位置的薄板模型,通过加载五周期的汉宁窗口正弦信号来模拟超声兰姆波在薄板中的传播,提取扇形扫描投影方式的走时数据。通过MATLAB编写扇形扫描滤波反投影算法程序,将提取到的走时数据代入算法中对薄板模型进行重建成像,缺陷信息清晰可见。最后搭建实验平台进行实验,得出实验的成像结果。由于实验条件的限制实验的成像质量并不如仿真时的成像质量高,但是成像效果也很可观,同时也分析了造成这种现象的原因。通过仿真与实验相结合的方式沿验证了该技术可以应用于工程实践中,为后续的研究奠定了基础。
[Abstract]:Carbon fiber composites are widely used in various fields because of their superior comprehensive properties. In the process of using carbon fiber composites, because of the defects of the materials themselves, or the defects of some components and equipment made of carbon fiber composite materials in the process of use, they will bring safety risks to the users. It even caused huge losses. Therefore, the detection of material defects is a particularly important link. Ultrasonic nondestructive testing (NDT) is an advanced nondestructive testing technology, and computer tomography is widely used in medical field. The main content of this paper is to combine ultrasonic nondestructive testing with computer tomography to detect and identify delamination defects of carbon fiber composites. The main contents are as follows: the propagation characteristics of ultrasonic wave in the same and anisotropic materials are studied by consulting the literature at home and abroad, and the dispersion equations and dispersion curves of ultrasonic Lamb in these two different materials are given respectively. It provides a theoretical basis for extracting the excitation signal and travel time of ultrasonic Lamb wave in finite element simulation and experiment. The theoretical basis of computer tomography technology is introduced in detail, and the mathematical formulas of parallel scanning filtering backprojection algorithm and sector scanning filtering backprojection algorithm based on central slice theorem are derived. At last, the detailed steps of the two algorithms are given. Finally, the sector scan filter backprojection algorithm is selected for the simulation and experiment of the image reconstruction algorithm. Carbon fiber composite multidirectional plate T300 / 5028 is chosen as the research object in this paper. The thin plate models with delamination defects in different positions are established by using ABAQUS finite element software. The propagation of ultrasonic Lamb wave in thin plate is simulated by loading sinusoidal signal of Hanning window with five periods, and the travel time data of sector scanning projection mode are extracted. The program of sector scan filter backprojection algorithm is written by MATLAB, and the extracted travel time data are replaced in the algorithm to reconstruct the thin plate model, and the defect information is clearly visible. Finally, the experimental platform is built and the imaging results of the experiment are obtained. Because of the limitation of the experimental conditions, the imaging quality of the experiment is not as high as that of the simulation, but the imaging effect is also considerable, and the reasons for this phenomenon are also analyzed. Through the combination of simulation and experiment, it is proved that this technique can be applied in engineering practice, which lays a foundation for further research.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB33

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