基于单模态的超声Lamb波技术在复合材料层合板中的健康检测研究

发布时间：2018-05-14 19:14

本文选题：超声Lamb波 + Chirp信号　；参考：《北京工业大学》2014年硕士论文

【摘要】：复合材料由于具有强度高、质量轻、比刚度大等优点而广泛应用在航空航天、风电、汽车等各个领域中，在这些领域复合材料出现任何损伤或者缺陷都有可能给国家财产和人民生命安全带来巨大威胁，因此发展一种能够对复合材料板进行快速健康检测的方法就很有必要。本文采用超声Lamb波技术对T300/QY8911复合材料层合板进行了健康检测技术研究，结合线性Chirp信号和椭圆成像定位算法实现了复合材料板中模拟缺陷的二维成像检测。本文的具体研究工作如下：（1）研究了线性Chirp信号及其在超声Lamb波检测中的应用。采用线性Chirp信号作为检测系统的激励信号，对其响应信号按照控制系统理论进行提取可以得到Chirp信号有效带宽范围内任意频率点和有效时宽范围内任意周期数的等效Tone burst响应信号。研究表明这一方法提高了检测效率和信号的信噪比，并且保证了检测条件的一致性。（2）提出了三种实现板类结构中Lamb波模态单一化的方法。首先是双压电片激励法，采用压电晶片作为激励传感器，将两个性能一致的压电晶片布置在板上下表面相同位置，给其施加幅值相同且相位也相同的电压信号可激励出单一的S0模态，施加幅值相同但相位相反的电压信号则可得到单一的A0模态。第二种是双压电片接收法，根据Lamb波结构特性，，对位于板上下表面相同位置的两个压电晶片的接收信号进行平均相加或平均相减可分别实现S0模态或A0模态的单一化。最后对压电传感器进行优化设计，压电晶片添加径向振动吸收层和阻抗匹配层可在低频段内激励出单一的A0模态，将压电晶片的结构设计成圆环状可激励出单一的S0模态。（3）开展了基于椭圆成像定位的单模态Lamb波技术在各向同性板和复合材料板中的缺陷成像研究。在被测板类结构上布置稀疏压电传感器阵列，用环氧树脂胶将一铝镁合金圆柱粘在复合材料板上作为模拟缺陷。对传感器阵列接收到的检测信号运用椭圆成像定位算法和数据融合方法实现了有机玻璃板尤其是T300/QY8911复合材料层合板上缺陷的二维成像检测。
[Abstract]:Composite materials are widely used in aerospace, wind power, automobile and other fields because of their advantages of high strength, light weight and high specific stiffness. In these fields, any damage or defect of composite materials may bring great threat to national property and people's life and safety. Therefore, it is necessary to develop a method that can be used to detect composite materials quickly and healthily. In this paper, the ultrasonic Lamb wave technique is used to detect the health of T300/QY8911 composite laminated plates. Combined with linear Chirp signals and elliptical imaging localization algorithm, two-dimensional imaging detection of simulated defects in composite plates is realized. The specific research work of this paper is as follows: The linear Chirp signal and its application in ultrasonic Lamb wave detection are studied. The linear Chirp signal is used as the excitation signal of the detection system. The response signal is extracted according to the control system theory to obtain the equivalent Tone burst response signal at any frequency point in the effective bandwidth range and any period number in the effective time and wide range of the Chirp signal. The results show that this method improves the detection efficiency and signal to noise ratio, and ensures the consistency of detection conditions. In this paper, three methods to realize the mode simplification of Lamb wave in plate structures are proposed. First of all, two piezoelectric wafers with the same performance are arranged in the same position on the upper and lower surface of the plate by using the piezoelectric wafer as the excitation sensor. The single S0 mode can be excited by applying the same amplitude and phase voltage signal, and the single A0 mode can be obtained by applying the same amplitude but opposite phase voltage signal. The second is the bimorph receiving method. According to the structure characteristics of Lamb wave, the received signals of two piezoelectric wafers located at the same position on the upper and lower surface of the plate can be added or subtracted to realize the S0 mode or the A0 mode. Finally, the piezoelectric sensor is optimized. The piezoelectric wafer with radial vibration absorption layer and impedance matching layer can excite a single A0 mode in the low frequency band, and the structure of the piezoelectric wafer can be designed as a ring to excite a single S0 mode. The defect imaging of isotropic and composite plates using single mode Lamb wave technique based on elliptical imaging localization is studied. A sparse piezoelectric sensor array was arranged on the structure of the measured plate, and an aluminum magnesium alloy cylinder was bonded to the composite plate by epoxy resin as a simulation defect. Using elliptical imaging localization algorithm and data fusion method to detect defects on plexiglass plate, especially on T300/QY8911 composite laminates, the detection signals received by sensor array are detected by two-dimensional imaging.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TB33;TB553

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