复合材料层合板Lamb波脱层缺陷检测研究

发布时间：2018-07-06 09:42

本文选题：Lamb波 + 复合材料　；参考：《重庆大学》2015年硕士论文

【摘要】：随着工业技术的快速发展,对工程应用中的材料属性要求越来越高。复合材料以高强度、大弹性模量、轻质量等方面优势在工业界得到广泛使用。复合材料结构的健康与否直接关系到系统的完整性和安全性,在复合材料层合板中最常见缺陷类型有纤维断裂、基体裂纹、脱层等,其中最难以检测的是内部脱层缺陷,这种缺陷严重影响复合材料的属性,在使用中存在着极大的安全隐患,国内外曾多次出现因脱层缺陷导致重大事故,所以复合材料中的脱层检测至关重要。本文使用Lamb波对脱层缺陷进行检测研究,分析Lamb波在复合材料板中传播原理并进行有限元模拟仿真,运用时间反转方法、小波分析法达到无基准检测目的,并根据概率成像原理实现复合材料板的脱层缺陷二维平面成像。本文首先研究Lamb波在复合材料板中传播理论方程以及Lamb波的检测原理,求得频散方程,绘制频散曲线;对时间反转方法做了详细理论分析,并利用时间反转法和小波分析法建立无基准脱层检测基础;通过对时反后聚焦信号的分析和与原始激励信号的比对,提出时反聚焦性能评价指标和小波差异系数评估指标,并以此作为下文中脱层区域成像的重要参数。在理论研究的基础上,利用有限元分析软件建立Lamb波在复合材料板中传播模型,以一维Lamb波线传播模型和二维Lamb波平面传播模型仿真对复合材料板导波传播特性进行深入研究。通过对检测信号的处理分析,确定是否存在脱层缺陷、定位脱层以及分析脱层尺寸对信号的影响,针对难处理的检测波形,提出“中心波峰去除法”,这一方法解决了信号微弱和缺陷反射回波与直达波混叠的问题,大大提高信号分析的有效性和准确性。利用时间反转法的重构性和小波差异系数实现层合板的二维概率脱层损伤成像,成功实现单处多层和多处脱层的成像显示,并对成像结果进行正确修正,能非常精确的定位到预设脱层损伤位置。
[Abstract]:With the rapid development of industrial technology, the requirements for material properties in engineering applications are becoming higher and higher. Composite materials are widely used in industrial circles with the advantages of high strength, large elastic modulus and light quality. The health of composite materials is directly related to the integrity and safety of the system, and is the most common in composite laminates. Defect types include fiber fracture, matrix crack, delamination and so on. The most difficult to detect is the internal delamination defect. This defect seriously affects the properties of composite materials. There is a great potential for safety in use. The delamination defects have occurred many times at home and abroad, so the delamination detection in the composite is very important. The Lamb wave is used to detect the delamination defect, and the propagation principle of Lamb wave in the composite plate is analyzed and the finite element simulation is carried out. The time reversal method and wavelet analysis are used to achieve the goal of non reference detection, and the two-dimensional plane imaging of the delamination defect of the composite plate is realized according to the principle of probability imaging. This paper first studies the Lamb wave. In the composite plate, the theoretical equation and the detection principle of Lamb wave are propagated, the dispersion equation is obtained and the frequency dispersion curve is drawn. The time reversal method is analyzed in detail, and the time reversal method and the wavelet analysis method are used to establish the basis of the non datum delamination detection, and the analysis of the time reversal focusing signal and the ratio of the original excitation signal to the original excitation signal. On the basis of the theoretical research, the propagation model of Lamb wave in the composite plate is established on the basis of the theoretical research, and the one dimension Lamb wave line propagation model and the two-dimensional Lamb wave plane propagation model are established. The simulation of the propagation characteristics of composite material plate guided wave. Through the analysis of the detection signal processing, determine whether there are delamination defects, location delamination and analysis of the influence of delamination size on the signal. In view of the difficult processing waveform, the "center wave peak removal method" is proposed. This method solves the weak and defect reflection of the signal. The problem of echo and direct wave aliasing greatly improves the effectiveness and accuracy of the signal analysis. Using the reconfiguration of the time reversal method and the wavelet difference coefficient, the two-dimensional delamination damage imaging of the laminate is realized, and the imaging display of the single layer and multiple delamination is successfully realized, and the correct correction of the imaging results can be made in a very accurate manner. Position to presupposition delamination damage.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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