【作者】 王瑜；

【导师】 袁慎芳；

【作者基本信息】 南京航空航天大学 ， 测试计量技术及仪器， 2012， 博士

【摘要】 目前，基于Lamb波的结构健康监测方法具有对结构小损伤敏感、主被动监测和大面积区域监测等特点，是国内外研究较多的一种飞机结构健康监测方法，具有很好的应用前景。空间滤波器监测和成像技术是结构健康监测中出现的新方法。空间滤波器结构健康监测技术是利用传感器阵列构成具有空间-波数域滤波属性的空间滤波器，利用空间滤波器的虚拟转动，实现对结构的多方位滤波扫描，判别结构中的冲击或损伤，并对判别结构进行有效的成像。本文重点研究了利用Lamb波与空间滤波器技术实现对飞机复合材料结构损伤和冲击的有效监测方法，从而将空间滤波器方法应用到了复合材料结构伤和冲击监测中，为结构健康监测提供了新的技术手段。本文取得的主要研究工作包括以下几个方面：（1）综述了目前基于Lamb波的结构健康监测技术和空间滤波器方法的研究背景和意义，给出了本文的研究内容。（2）从理论上对Lamb波在板结构中传播的波数域特征进行了讨论，对Lamb波信号的空间滤波理论进行了深入的研究，得到了理想空间滤波器的解析表达式及空间滤波器的适用范围，并对空间滤波器的空间滤波特性进行了详细的讨论。对常规的空间滤波器成像方法进行了理论研究和实验验证，为后文改进滤波器的提出奠定了理论和实验基础。（3）提出了一种基于Hilbert变换的空间滤波器结构损伤成像的优化方法。该方法利用Hilbert变换直接构造响应信号的复信号实现空间-波数域滤波信号合成，解决了目前方法依赖结构参数的问题，从而将该方法应用到了复合材料结构的损伤诊断应用中。（4）提出了一种基于Shannon连续复数小波变换的空间滤波器结构成像的优化方法。该方法利用Shannon连续复数小波的等幅频率窗特性，解决了冲击产生的宽带信号的窄带提取问题，弥补了Hilbert变换在这方面的不足，使得该方法既能应用于复合材料结构的主动损伤监测又能应用于被动的冲击监测。（5）提出了一种基于空间滤波器的基准优化损伤成像方法，该方法通过结构健康状态和损伤状态成像结果的对比实现损伤判别，避免了利用差信号进行损伤成像的做法，降低了对结构健康状态下基准响应信号的依赖。更多还原

【Abstract】 At present, the method of structural health monitoring based on Lamb wave, which has goodapplication foreground, is one of the basic study of aircraft structure at home and abroad due to itssensitivity to small defects, active and passive monitoring and large area monitoring in plate structures.The spatial filter monitoring and imaging technology is a new method for structural health monitoring(SHM), which uses the sensors array to constitute spatial filter with space-wave number domainfiltering properties and uses the method of virtual rotation of spatial filter to realize themulti-directional scanning for the structure, identify the structural impact or damage and get theeffective mapped image of the recognition results. The goal of research in this dissertation is to detecteffective monitoring and damage information based on Lamb wave and spatial filter technology. Thisresearch lays the foundation for developing new technical means of impact and damage monitoring ofComposite Material structures in structural health monitoring.The main works and novel researches done in this dissertation include:(1) Discussing and analyzing multi-mode which lamb wave propagate, dispersion characteristicsand wave number characteristics of lamb wave, we have achieved the wave number dispersion curvesof lamb wave.(2) After researching the model, which is compounded by basic signal of linear sensor array, wecan get the dividing strip of near-field and far-field. After studying spatial filtering theory of lambwave signal deeply, we obtain the analytic expression and the scope of application of the ideal spatialfilter. The spatial filtering characteristics of the spatial filter have been discussed in detail. Theconventional imaging method of the spatial filter has been researched in theory and verified inexperiment. The feasibility of the spatial filter method testing structural damage has been verified inmetal structure. All above has provided theoretical and experimental basis for the improvement of thespatial filter in the following passage.(3) Improved imaging method of spatial filter structural damage based on Hilbert transform isproposed, the method uses Hilbert transform to construct the complex signal to participate in thesynthesis of spatial filtering signals. As it avoids the conventional use of structure parameters for thesimplified approach on the imaginary part, thus the spatial filter method is extended to the applicationof composite material structural damage diagnosis.(4) Improved imaging method of spatial filter structure, which is based on Shannon continuouscomplex wavelet transform has been put forward. The method can be applied not only to active damage monitoring but also to the passive impact monitoring，which makes up the disadvantage ofthe Hilbert transform. Thus the spatial filter method is extended to the application of the passiveimpact monitoring.(5) The nominal optimal damage imaging method based on the improved spatial filter has beenput forward to overcoming the error on signal attainment and the difficulties that the temperaturechanges make the baseline damage monitoring method difficult to carry out. The engineeringapplication of the structure health monitoring technology has been promoted by the method.(6) By taking the oil tank of the real aircraft as the research object, we have verified theimproved spatial filter method and the nominal optimal damage imaging methods that are proposed inthe paper.更多还原