【作者】 严刚；

【导师】 周丽；

【作者基本信息】 南京航空航天大学 ， 飞行器设计， 2005， 硕士

【摘要】 对先进复合材料结构进行连续的实时在线监测是未来飞行器结构完整性研究的关键问题之一。本文对能无缝集成在复合材料结构中的基于压电传感网络的嵌入式结构健康监测系统进行了研究,提出将瞬态应力波(Lamb波)和先进数据处理方法(小波分析)相结合的方法,对复合材料结构进行在线的连续监测,近乎实时地检测出损伤的发生,准确判定损伤的位置,估算出损伤的程度,并将这些结果和信息可视化。本文首先深入研究了瞬态应力波在复合材料结构中的传播问题,利用高阶板近似理论建立了应力波在各向异性复合材料层合板结构中的随传播角度变化的弥散关系,并对应力波在各向异性复合材料结构中的传播进行了有限元模拟;然后用小波变换对由压电传感元件激励和接收的应力波信号在时频域进行分析,提取特征信息,量测出应力波在结构中实际传播的速度,并与理论结果进行了比较;在此基础上开发了基于应力波和小波分析的损伤识别算法,使用遗传算法准确确定损伤位置和损伤尺寸;最后对利用应力波进行损伤成像进行了研究,将损伤情况进行可视化;在这过程中集成一套原型结构健康监测系统,对复合材料结构的模拟损伤和冲击损伤进行监测和识别的实验研究。实验结果表明了本文所提出的方法的可应用性和有效性。本文的研究得到了国家自然科学基金项目,基于无线智能传感器网络复合材料结构健康监测的先进损伤识别技术(项目编号:10572058),和航空科学基金项目,复合材料结构健康监测系统中的先进损伤识别技术(项目编号:04I52063)的资助。更多还原

【Abstract】 One of the critical tasks in the research of structural integrity for future’s aircraft is to continuously on-line monitor the advanced composite structure in (near) real-time. This study presents a preliminary study on the piezoelectric-based built-in structural health monitoring system which can be integrated seamlessly into the composite structure. A damage detection and identification method using Lamb waves and time-frequency analysis is proposed for continuously monitoring of composites, detecting the damage in near real-time, localizing it accurately, sizing it approximately and visualizing it finally.In this study, Lamb waves propagating in anisotropic laminates are first modeled analytically using higher-order plate theory and the direction-dependent dispersion relations of the waves are established. Finite element analysis is employed to simulate the wave propagation in anisotropic composite structure. Wavelet transform is applied to the wave signals actuated and sensed by piezoelectric transducers in the time-frequency domain to extract the characteristic information such as time arrival to measure the actual wave group velocities propagating in composite laminates and compare them with the results given by plate theory. Combined with the theoretically computed and actually measured wave velocity, a genetic algorithms optimization technique is employed to identify the location and size of the damage. A damage imaging approach is adopted and improved to image the damage. The applicability and effectiveness of the proposed method is demonstrated by experimental studies.This research is supported by the National Natural Science Foundation of China under Grant No.10572058, and by the Science Foundation of Aeronautics of China under Grant No.04I52063.更多还原