【作者】 张利绍；

【导师】 李剑敏； 陈换过；

【作者基本信息】 浙江理工大学 ， 机械设计及理论， 2012， 硕士

【摘要】 结构损伤检测技术广泛地应用在飞行器、桥梁和海洋等大型复杂结构中，基于Lamb波的无损检测技术是结构无损检测系统中重要的检测方法。本文根据Lamb波传播理论，采用主动Lamb损伤检测技术，通过粘贴在结构表面的压电传感器，加载合适的激励信号。激励信号在结构中传播，通过对采集到的响应信号进行分析及模式处理，初步实现了二维结构的损伤判断。采用对称加载和计算损伤百分比的方法，判断了加筋板结构中的多损伤位置和损伤程度。论文主要工作如下：首先，本文探讨了Lamb波在复合材料结构中的传播特性，绘制出了Lamb波相速度和群速度的频散曲线图，根据频厚积的关系，研究了实验所选频率范围内适于复合材料损伤检测的最优中心频率。其次，本文分析了Lamb波在复合材料板中损伤前后的传播速度，根据损伤前后动态响应信号的差信号中损伤反射波包延迟时间，采用椭圆定位方法判断损伤位置。文中分别对细长板、正方形板、曲面板和加筋板进行了损伤定位。其中对等效简化后的加筋板结构进行了多损伤位置和损伤程度判断。最后，计算并判断了蒙皮和筋板结构上不同损伤位置；对比判断加筋板结构上不同程度损伤的损伤反射比，建立损伤程度和损伤反射百分比的对应关系。通过对比采集到的结构损伤前后动态响应信号，消除掉损伤前后动态响应信号中的公共信息，得到只包含损伤信息的差信号，根据差信号中损伤波包飞行时间和波包峰值衰减系数判断损伤位置和损伤程度。分析结果表明，基于Lamb波的全局损伤检测技术，能够快速检测大面积复杂结构。更多还原

【Abstract】 In modern society, structural health monitoring system is widely used in aircraft, bridge,offshore platforms and large and complex structures. The Lamb wave based structural damageddetection technology plays a very important role in structural health monitoring system.This study adopts active detection technique based on Lamb Wave to monitor damage incomposite materials. The suitable excitation signal be loaded by the sensors pasted on thestructure surface. The excitation signal propagation in structure, by comparative analysis andpattern processing response signals collected before and after damage happens, the damagelocation can be determined. Through symmetrical load and calculate percentage of damage tojudge the stiffened damage locations and degree.The main works are showed as follows:Firstly, the propagation characteristics of Lamb wave in composite structure are discussed.According to the phase velocity and group velocity dispersion curve, the optimal centralfrequency is studied in the range of selective frequency.Secondly, judge and analysis the propagation velocity of composite before and after damagehappens, according to the arrival time of the Lamb wave group velocity. The damage locationswere judged by the elliptical location method. In this paper, the damage location is judged fornarrow plate, square plate, curved plate and stiffened plate respectively.Finally, the damage degree of stiffened plate was judged by different damage reflectance;the corresponding relationship between damage degree and damage reflectance be establish bycalculation results.The difference signals were calculated by eliminating common information of pre and postdynamic response signals. Damage location and degree be judged by time of fly and attenuationcoefficient of wave packet peak according to difference signals. The results show that large andcomplex structure can be rapidly detected by the technical research on global damage detecttechnology based on Lamb wave.更多还原