基于脉冲涡流的多层异种金属材料内部缺陷检测研究

发布时间：2018-11-23 12:28

【摘要】：多层异种金属粘接结构具有许多优点,比如比强度高,比模量高,抗疲劳和减震性能强,该种结构被广泛应用在航空航天、国防、核工业等领域,检测并保证结构的质量安全具有重大意义。由于制造手段的固有短板和生产环境的影响,层板粘接处容易产生的缺陷种类有脱粘和气泡。在生产、组装和实际使用过程中,由于这些过程伴随着机械加工、碰撞和结构疲劳,这将导致裂纹、划痕等缺陷的出现。这些缺陷大多是亚表面缺陷,隐藏在构件内部,容易导致构件的物理属性发生改变,在毫无察觉的情况下逐渐影响构件的可靠性和安全性。无损检测是以不损害被测对象的使用性能为前提,应用物理原理和化学现象,对构件进行检验,以此评价被测件的连续性、完整性、可靠性和安全性。脉冲涡流检测是众多无损检测技术中的一个重要分支,它相比其他的检测方式有着检测速度快,检测深度深等优点。本文针对多层异种金属粘接结构的缺陷检测,对脉冲涡流检测进行了研究。具体的工作内容如下:(1)基于脉冲涡流检测技术的理论,使用COMSOL多物理场耦合仿真软件搭建了二维轴对称检测模型。通过仿真,讨论了脉冲涡流检测传感器结构参数对检测结果的影响。并获得脉冲涡流探头研制的最优结构参数。(2)根据仿真结果得到的脉冲涡流探头的最优结构参数,搭建了脉冲涡流检测系统平台。包括激励信号的获取、激励信号功率放大、激励和检测探头的研制、数据采集和上位机软件编写,并使用标准样件来验证系统的稳定性和准确性。(3)利用研制的脉冲涡流检测平台对制备的多类缺陷大小不等的多层异种金属粘接结构进行缺陷检测,并在时域和频域下对检测数据进行分析。着重讨论了缺陷在不同特征选择情况下的检测结果,这里包括:信号在时域下检测信号差分信号特征和频域下基波分量幅值特征、三次谐波幅值特征以及两者之间的比值特征。通过实验,本文所设计的脉冲涡流检测系统对于非铁磁性材料导体的检测深度可达8mm(实验标准试件:铝合金),并且分析和建立了不同深度缺陷与特征信号的线性映射关系。对于多层异种金属材料内部缺陷检测,本文所涉及的系统能成功检测出直径为5mm,4mm,3mm的第一二层层间缺陷。
[Abstract]:Multilayer dissimilar metal bonding structures have many advantages, such as high specific strength, high specific modulus, strong fatigue and shock absorption performance. This kind of structure is widely used in aerospace, national defense, nuclear industry and other fields. It is of great significance to detect and ensure the quality and safety of the structure. Due to the influence of the inherent short plate and the production environment of the manufacturing means, the kinds of defects which are easy to produce in the laminate bonding are debonding and bubble. In production, assembly and practical use, these processes are accompanied by mechanical processing, collision and structural fatigue, which will lead to cracks, scratches and other defects. Most of these defects are subsurface defects, which are hidden inside the components, which can easily lead to the change of the physical properties of the components, and gradually affect the reliability and security of the components without notice. Non-destructive testing (NDT) is to evaluate the continuity, integrity, reliability and safety of the tested parts by using physical principles and chemical phenomena. Pulse eddy current testing is an important branch of many nondestructive testing technologies. It has the advantages of fast detection speed and deep detection depth compared with other detection methods. In this paper, the pulse eddy current testing is studied for the defect detection of multilayer dissimilar metal bonding structure. The main contents are as follows: (1) based on the theory of pulsed eddy current testing, a two-dimensional axisymmetric detection model is built by using COMSOL multi-physical field coupling simulation software. Through simulation, the influence of the structure parameters of the pulsed eddy current detection sensor on the test results is discussed. The optimal structure parameters of the pulsed eddy current probe are obtained. (2) according to the optimal structure parameters of the pulse eddy current probe, the platform of the pulse eddy current detection system is built. Including the acquisition of the excitation signal, the power amplification of the excitation signal, the development of the excitation and detection probe, the data acquisition and the programming of the upper computer software, Standard samples are used to verify the stability and accuracy of the system. (3) using the developed pulse eddy current testing platform, the defect detection of multi-layer dissimilar metal bonding structures with different sizes of multi-class defects is carried out. The detection data are analyzed in time domain and frequency domain. The detection results of defects in different feature selection cases are discussed emphatically, which include: signal differential signal characteristics in time domain, fundamental wave component amplitude characteristics in frequency domain, third harmonic amplitude characteristics and ratio characteristics between them. Through experiments, the testing depth of the pulsed eddy current testing system for non-ferromagnetic material conductors is up to 8mm (experimental standard specimen: aluminum alloy), and the linear mapping relationship between different depth defects and characteristic signals is analyzed and established. For the internal defect detection of multi-layer dissimilar metal materials, the system in this paper can successfully detect the defects between the first and second layers with the diameter of 5 mm / 4 mm / 3 mm.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG115.28

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