基于Lamb波信号相关系数的结构损伤识别研究

发布时间：2018-02-20 20:44

本文关键词： 结构健康监测信号相关系数 Lamb波无基准损伤识别损伤成像　出处：《南京航空航天大学》2016年硕士论文　论文类型：学位论文

【摘要】：本文对航空结构中基于信号相关系数的损伤识别方法进行了研究。提出了一种有效信号段自提取算法,并在此基础上分别发展了基于信号相关系数的有基准和无基准的损伤识别方法。并探究了裂纹损伤程度的表示方法。首先,本文研究了一种基于信号相关系数的有基准识别及成像方法。先将待检测结构进行区域分割,分割成若干个子区域,然后根据压电传感器间的距离和Lamb波的波速,自动计算并提取出接收传感器接收到的有效信号段长度。利用提取出的有效信号段计算基于信号相关系数的损伤指标,最后利用快速成像算法将损伤的位置成像出来。其次,本文研究了一种基于信号相关系数的无基准损伤识别方法。通过在结构上布置一个矩形阵列,形成多个同方向的激励-接收路径。利用提取出的有效信号段计算路径之间的信号相关系数。比较同方向的路径之间的信号相关系数是否为1或者接近1,判断出不存在损伤的路径,得到某一方向上的无损信号。将有损信号与无损信号进行相减得到损伤点的散射信号。最后通过椭圆定位方法对损伤进行定位。最后,本文探究了基于信号相关系数的损伤程度表示方法。在结构激励端的两侧对称布置一对传感器,通过反相激励激发出单一的A0波。对裂纹位置不同、尺寸相同,裂纹位置尺寸相同、扩展方向不同的两种情况下进行探究。
[Abstract]:In this paper, the damage detection method based on signal correlation coefficient in aeronautical structures is studied, and an effective signal segment self-extraction algorithm is proposed. On the basis of this, the damage identification method with reference and without reference is developed based on signal correlation coefficient, and the expression method of crack damage degree is explored. First of all, In this paper, a method of reference recognition and imaging based on signal correlation coefficient is studied. Firstly, the region of the structure to be detected is divided into several sub-regions, and then according to the distance between piezoelectric sensors and the velocity of Lamb wave, The length of the effective signal segment received by the receiving sensor is automatically calculated and extracted. The damage index based on the signal correlation coefficient is calculated by using the extracted effective signal segment. Finally, the location of the damage is imaged by the fast imaging algorithm. Secondly, In this paper, a nonreference damage detection method based on signal correlation coefficient is studied. Form multiple excitation-receive paths in the same direction. Use the extracted effective signal segments to calculate the signal correlation coefficients between paths. Compare whether the correlation coefficients between paths in the same direction are 1 or close to 1, and determine whether the correlation coefficients between paths in the same direction are 1 or close to 1. There is no damage path, A lossless signal in a certain direction is obtained. The scattering signal of damage point is obtained by subtracting the lossy signal from the lossless signal. Finally, the damage is located by elliptical localization. Finally, In this paper, the method of expression of damage degree based on signal correlation coefficient is studied. A pair of sensors are arranged symmetrically on both sides of the excitation end of the structure, and a single A0 wave is excited by inverse excitation. The crack position is different and the size is the same. The crack location size is the same and the propagation direction is different.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：V267

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