电磁激励下金属板裂纹缺陷的高频响应机制研究

发布时间：2018-06-12 03:16

本文选题：电磁超声 + 电磁声发射　；参考：《河北工业大学》2016年博士论文

【摘要】：开展高质量、新型无损检测技术的探索工作对提高金属构件的缺陷检测效率、保证设备健康稳定运行有很强的实际意义。其中电磁应力波检测技术因具有无需耦合剂、极端环境适应性强、检测效率高等优势,受到了广泛的关注。然而,在电磁应力波检测技术中,除线性电磁超声检测有较多的研究之外,而有关电磁声发射检测和非线性电磁超声检测的研究却较少,有些关键问题尚不清楚,从而限制了该技术的推广应用。本文进行了用于铝合金裂纹的电磁应力波检测技术的研究,提出了基于线性电磁超声、电磁声发射、非线性电磁超声检测方法对不同尺度裂纹的检测方案,旨在为该技术的工程应用和推广奠定理论基础。本文主要研究工作如下:(1)电磁超声对宏观裂纹检测问题的研究:在电磁超声原理基础上,将超声点源解析与电磁-结构完整换能过程的有限元仿真相联立,而后对参数化电磁超声换能器体波特征进行分析,进而分析超声体波对体内孔洞缺陷的探测、超声表面波对表面开口裂纹检测的能力。研究结果表明,电磁超声体波、表面波对于宏观裂纹的尺寸、位置、数量等特征均具有很好的检测效果。(2)对于电磁声发射的理论研究:本文从位错动力学及自由电子理论两个方面研究了电磁载荷产生声发射效应问题,构建了电磁加载声发射能量释放理论公式。对电磁声发射参数与电磁载荷之间的关系进行了研究,利用希尔伯特-黄变换方法处理电磁声发射信号特性。研究结果表明,电磁声发射的产生是漂移电子与位错之间的能量交换并推动位错运动的结果。(3)电磁声发射与电磁超声复合检测的研究:本文提出了电磁超声-电磁声发射复合检测方案,设计了相应的复合线圈、换能器静磁场和阻抗匹配,并分析了电磁超声-电磁声发射复合检测效率,实现了复合检测中两种检测方法的优势互补。研究结果表明,复合检测中电磁声发射模式可实现长距离声发射信号特征的传输。(4)非线性电磁超声检测方法研究:本文通过将非线性超声与电磁超声技术相结合,克服传统超声对微细裂纹以及金属构件早期塑性变形检测困难的问题。分析斜入射超声波与微细裂纹非线性效应作用情况,利用仿真、实验对微细裂纹、塑性变形的超声非线性效应进行分析。研究结果表明,非线性电磁超声具有对金属构件早期损伤检测的可行性。
[Abstract]:The exploration of high quality and new nondestructive testing technology is of great practical significance in improving the efficiency of defect detection of metal components and ensuring the healthy and stable operation of the equipment. Electromagnetic stress wave detection technology has attracted wide attention because of its advantages such as no coupling agent, strong adaptability to extreme environment and high detection efficiency. However, in the electromagnetic stress wave detection technology, except for the linear electromagnetic ultrasonic detection, there are few studies on electromagnetic acoustic emission detection and nonlinear electromagnetic ultrasonic detection, and some key problems are not clear. Therefore, the popularization and application of this technology are limited. In this paper, the detection technology of electromagnetic stress wave for aluminum alloy cracks is studied. Based on linear electromagnetic ultrasonic, electromagnetic acoustic emission and nonlinear electromagnetic ultrasonic detection, the detection scheme of crack at different scales is proposed. The aim is to lay a theoretical foundation for the engineering application and popularization of this technology. The main research work of this paper is as follows: based on the principle of electromagnetic ultrasonic, the ultrasonic point source analysis is combined with the finite element simulation of the complete electromagnetic structure energy transfer process. Then the characteristics of body wave of parameterized electromagnetic ultrasonic transducer are analyzed, and the detection of hole defects and the ability of ultrasonic surface wave to detect open surface cracks are analyzed. The results show that the size and position of electromagnetic ultrasonic body wave and surface wave for macroscopic crack, The theoretical study of electromagnetic acoustic emission (EAE): in this paper, the acoustic emission effect caused by electromagnetic load is studied from dislocation dynamics and free electron theory. A theoretical formula for the energy release of electromagnetic loaded acoustic emission is established. The relationship between electromagnetic acoustic emission parameters and electromagnetic load is studied. Hilbert-Huang transform method is used to deal with the characteristics of electromagnetic acoustic emission signals. The results show that The generation of electromagnetic acoustic emission (EAE) is the result of energy exchange between drift electron and dislocation and the result of promoting dislocation motion. The corresponding composite coil, transducer static magnetic field and impedance matching are designed, and the efficiency of electromagnetic ultrasonic and electromagnetic acoustic emission composite detection is analyzed. The advantages of the two detection methods are complementary. The results show that the electromagnetic acoustic emission mode can realize the transmission of the characteristics of long range acoustic emission signal in the composite detection. The research of nonlinear electromagnetic ultrasonic detection method: this paper combines the nonlinear ultrasonic and electromagnetic ultrasonic technology. To overcome the problem of traditional ultrasonic detection of micro cracks and early plastic deformation of metal members. The effect of oblique incidence ultrasonic wave on the nonlinear effect of micro crack is analyzed. The ultrasonic nonlinear effect of micro crack and plastic deformation is analyzed by simulation and experiment. The results show that nonlinear electromagnetic ultrasound is feasible for early damage detection of metal components.
【学位授予单位】：河北工业大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TG115.28

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