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1、摘 要硕士学位论文多层管界面脱粘缺陷的电磁超声检测方法研究学位申请人：指导教师： 教授， 研究员类别（领域）：工程硕士（航天工程）年 月论文题目：多层管界面脱粘缺陷的电磁超声检测方法研究本研究得到国家磁约束聚变项目（2013GB113005），国家自然科学基金（51277139, 11321062）及国家973项目（2011CB610303）资助类别（领域）：工程硕士（航天工程）学位申请人：指导教师： 教授， 研究员摘 要偏滤器是托卡马克装置的重要组成部分，起着移除聚变残灰以及冷却面向等离子体部件的作用，是保证等离子体正常运行的关键部件之一。由于面向等离子体部件需要承受来自等离子体的强大热负荷
2、，偏滤器垂直靶板大量采用穿管型部件，以抵抗高温和有效移除热量。钨铜穿管型部件的合金铜换热管和钨块通过中间无氧铜层利用热等压焊接技术连接，局部构成了典型的多层、异材管状结构。多层热等压焊接管在航天航空结构中也有大量使用，其结构的完整性对飞行器安全具有重大影响。由于制作工艺复杂，在制备和使用过程中，异材焊接界面可能发生脱粘等缺陷，因此需要采用无损检测手段对界面焊接质量进行评估。国内外相继开发了红外热成像法、超声波检测法以及涡流检测法用于钨铜穿管型部件的界面检测，但这些方法在检测精度及检测效率上尚有不足。电磁超声无损检测技术由于其独有的特性，有望用于提高多层管结构界面脱粘缺陷检测的有效性。针对以上研
3、究背景，本论文主要研究电磁超声技术在多层结构界面脱粘缺陷检测中的有效性。主要内容包括：多层管用的电磁超声数值模拟程序的开发；针对小径管提出了一种旋转磁场管用电磁超声新方法；所提方法对多层结构界面脱粘缺陷检测的有效性的实验验证。具体研究内容及主要结果如下：（1）基于已有平板的数值模拟程序，开发了多层管电磁超声数值模拟程序，通过超声场传播规律的分析、超声波波速计算值与理论值的对比以及仿真结果与实验结果的对比，验证了数值模拟程序的正确性。（2）建立了钨铜穿管型部件的数值计算模型，提出了两种典型的管用电磁超声探头结构，利用开发的数值模拟程序进行了界面脱粘缺陷检测的电磁超声信号仿真；搭建了电磁超声实验系
4、统，自制了电磁超声探头，进行了单层铝板以及铝铜双层板的电磁超声扫查实验。数值模拟和实验结果均表明：电磁超声方法用于多层结构界面脱粘缺陷检测非常有效。（3）提出了一种基于旋转磁场的管用电磁超声新方法，开发了旋转磁场电磁超声检测数值模拟程序，对三相绕组内部空间的磁场分布、旋转磁场的速度效应以及在旋转磁场作用下的电磁超声检测信号进行了计算分析，同时还开展了旋转磁场电磁超声关键问题的验证实验。数值模拟和实验结果均表明：旋转磁场电磁超声方法对多层管界面脱粘检测是可行的。关 键 词：偏滤器；多层管部件；界面脱粘；电磁超声检测；旋转磁场 论文类型：应用基础IIIABSTRACTTitle: Developm
5、ent of EMAT for Detection of Delamination of Multilayered TubesProfessional Fields: Spaceflight EngineeringThis study is supported by National Magnetic Confinement Fusion Program of China (Grant.2013GB113005), the Natural Science Foundation of China (Grant No. 51277139, 11321062) and the National Ba
6、sic Research Program of China (Grant No.2011CB610303)Applicant: Guicai Yang Supervisor: Prof. Zhenmao Chen, Prof. Yang YuABSTRACTDivertor is one of the key plasma facing components (PFC) in Tokamak. The major function of the divertor is to remove waste and heat produced by nuclear fusion to make it
7、possible for the continuous operation of fusion plasma. To bear the huge heat flux from the core plasma, heat sink is necessary in the divertor structure. In the vertical target of divertor, heat sink of a mono-block structure is adopted which consists of CFC/W block and a Cu alloy tube that are wel
8、ded together by means of the hot isostatic press technology (HIP). The multilayer tube is also a typical structure widely used in the aerospace engineering. During the fabrication and operation, delamination or surface cracking may occur due to the complicated fabrication condition and severe heat e
9、nvironment, which is a key threat to the safety of the multilayered tube. In order to guarantee the structural integrity of divertor, nondestructive testing technique is necessary for the detection of delamination of welding joints of W mono-blocks. Infrared thermography, ultrasonic testing and eddy
10、 current testing have already been adopted for the inspection of the W mono-blocks, but they still have efficiency and precision problems. Electromagnetic acoustic testing (EMAT) has potential to solve these problems due to its particular features, but its feasibility has to be demonstrated.Based on
11、 these backgrounds, this thesis focus on the development of EMAT for the detection of delamination in multilayered structures especially a multilayered tube. The major works include the establishment of the numerical simulation method and a code for multilayered structures, development of a new EMAT
12、 based on rotating bias magnetic field, and experimental verification. The detailed research work and major results are as follows: Based on the code for EMAT of monolayer flat plate, a numerical simulation code for nonmagnetic multilayered tube were established and its validity was verified through
13、 an analysis of ultrasonic wave field, comparison of the simulated ultrasonic wave velocity with that of the theoretical value and experimental validation. Both the simulation results and the experimental results show that the simulation method and code are correct.To investigate the feasibility of
14、EMAT for detection of delamination of mono-blocks, a numerical simulation model of W mono-block was established with two EMAT probes proposed for multilayer tube inspection and the EMAT signals were calculated for different kinds of delamination defects. In addition, a shear wave vertical EMAT probe
15、, two kinds of plate test pieces with artificial delamination defects and an EMAT testing system were fabricated and established. Both numerical and experimental results reveal that EMAT is suitable for the inspection of delamination in multilayered structures.To cope with EMAT inspection for multil
16、ayer tube of small diameter, an innovative EMAT method using rotating bias magnetic field was proposed for NDT of delamination defects in tube subsurface. A numerical code based on Biot-Savartlaw was developed to analyze the distribution of magnetic field generated by three phase windings, and the influence of the rotation of magnetic field on the EMAT signals w
