基于主动Lamb波的复合材料层合板冲击损伤识别研究

发布时间：2018-05-05 06:22

本文选题：Lamb波 + 结构健康监测　；参考：《哈尔滨工业大学》2015年硕士论文

【摘要】：在过去的二十年间,结构健康监测技术(SHM)因其在薄板结构中优于传统的无损检测技术,而获得了学术界的广泛关注。在不同研究方法中,基于Lamb波的方法有很多优点而被广泛应用。压电陶瓷传感器被用来在薄板结构中激励和探测Lamb波,通过激励和探测经结构不同部位反射回的Lamb波,我们可以判断损伤的位置和程度。复合材料层合板被大量应用于航空航天领域,但在其服役过程中常经受冲击载荷。所以,针对复合材料层合板冲击损伤的结构损伤识别研究是十分有意义的。本文的主要研究内容包括:首先对Lamb波的基本特性进行了详细的阐述,从构建各向同性体中弹性波的运动方程入手,代入板的边界条件,得到了各向同性材料板中Lamb波的频散方程,以及相速度与群速度的关系,以铝板和钢板为例绘制了频散曲线。推导了截止频率的表达形式,指出了其应用意义。根据分波理论,推导了各向异性材料层中,Lamb波的频散方程。这些工作为后面的研究打下了基础,提供了理论依据。接着详细地介绍了Lamb波在复合材料层合板中传播行为有限元模拟的相关内容。首先介绍了显式动态算法,接着对传感器和损伤的模型建立分别进行了说明和相关理论阐述,然后给出了有限元仿真的具体过程以及相关参数设置的解释,最后简单分析了有限元仿真结果。总的来说,完整的提供了一套关于含冲击损伤复合材料层合板中Lamb波传播行为有限元仿真的方法。最后针对第三章有限元仿真所得结果,进行了简单的信号处理及损伤位置识别。利用典型频域法快速傅里叶变换及时频法小波变换进行了信号处理,比较了不同频率下Lamb波的传播特性,定性地判断了损伤的存在性,并且对比了时频法与频域法的优缺点。之后基于Lamb波信号的飞行时间,利用椭圆定位法对损伤位置进行了粗略的识别,考虑到算法中的近似,误差范围可以接受。同时也侧面地证明了前面所用建模仿真方法的正确性和有效性。
[Abstract]:In the past 20 years, structural health monitoring (SHM) technology has attracted much attention because it is superior to traditional nondestructive testing (NDT) technology in thin plate structures. In different research methods, the method based on Lamb wave has many advantages and is widely used. Piezoelectric ceramic sensors are used to excite and detect Lamb waves in thin plate structures. By exciting and detecting Lamb waves reflected from different parts of the structure, we can judge the location and extent of damage. Composite laminates are widely used in aerospace field, but they are often subjected to impact load during their service. Therefore, it is of great significance to study the structural damage identification of composite laminated plates. The main contents of this paper are as follows: firstly, the basic characteristics of Lamb waves are described in detail, and the boundary conditions of plates are replaced by constructing the equations of motion of elastic waves in isotropic bodies. The dispersion equation of Lamb wave in isotropic plate and the relationship between phase velocity and group velocity are obtained. The dispersion curves of aluminum plate and steel plate are plotted. The expression of cutoff frequency is derived and its application significance is pointed out. The dispersion equation of Lamb wave in anisotropic material layer is derived according to the theory of fractional wave. These work have laid the foundation for the later research and provided the theoretical basis. Then the finite element simulation of Lamb wave propagation in composite laminates is introduced in detail. Firstly, the explicit dynamic algorithm is introduced, then the modeling of sensor and damage is explained and related theories are explained, then the concrete process of finite element simulation and the explanation of relevant parameter setting are given. Finally, the finite element simulation results are simply analyzed. In general, a complete finite element simulation method of Lamb wave propagation in composite laminates with impact damage is provided. Finally, a simple signal processing and damage location identification are carried out according to the results of finite element simulation in chapter 3. In this paper, the fast Fourier transform (FFT) method in frequency domain is used to process the signal, the propagation characteristics of Lamb waves at different frequencies are compared, the existence of damage is judged qualitatively, and the advantages and disadvantages of time-frequency method and frequency-domain method are compared. Then, based on the time of flight of Lamb wave signal, the damage location is roughly identified by elliptical localization method. Considering the approximation in the algorithm, the error range is acceptable. At the same time, the correctness and validity of the previous modeling and simulation methods are also proved.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB33

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