【作者】 赵继辰；

【导师】 吴斌；

【作者基本信息】 北京工业大学 ， 机械工程， 2013， 博士

【摘要】 在我国，83%以上的电力是由火力发电厂提供的。火力发电厂的高压加热器和凝汽器大都采用黄铜管、碳钢或不锈钢管作热交换管。这些管材除了在生产和安装时留下的隐性缺陷并在运行过程继续扩展外，在管道使用过程还会产生各种新的缺陷，如管内沉积物引起的点腐蚀、化学气体诱发形成的管外环形槽状腐蚀坑以及管内流水冲击磨蚀等，从而导致泄漏。工业管道的超声导波无损检测技术与健康状况评价方法日趋成熟，超声传感器在工程实际中得到了一定的应用，取得了良好效果。而针对大型火电站锅炉管网这种特殊的检测对象，将无损检测技术用于波纹管这类具有复杂外壁结构的热交换管损伤检测则相对较少。本文基于经典的线弹性理论，针对螺旋波纹管这类具有复杂外壁结构的板管结构，从理论推导、数值计算、有限元仿真、传感器参数设计与性能优化、试验系统搭建、缺陷识别与定位、检测精度评估、影响因素分析等方面开展研究工作，具体研究内容如下：(1)基于经典的自由平板中导波频散方程的推导方法，将波纹板的波纹参数引入到频散方程中，得到了波纹板中SH波和Lamb波的频散方程。采用二分法数值求解了频散方程，并将得到的相速度和群速度频散曲线与平板中导波的传播特性进行了比较，研究了导波的群速度随波纹参数的变化规律。(2)基于经典的自由空心圆柱中导波频散方程的推导方法，得到了波纹管中扭转模态和纵向模态导波的频散方程，比较了各导波模态对波纹参数的敏感程度。同时在Abaqus软件平台上对超声导波在波纹结构中的传播特性进行了有限元仿真，分析了波纹结构中导波的实际传播距离随波纹参数的变化规律。(3)分析了材料的纵波波速和横波波速发生变化时，超声导波相速度和群速度频散曲线的变化趋势。对于相同程度的波纹参数改变量而言，比较了波纹板和波纹管中不同模态导波对波纹变化的敏感程度。(4)通过分析磁致伸缩效应及超声导波的特性，提出了磁致伸缩传感器的优化方案即多层绕线线圈传感器，实现了纵向模态超声导波的激励及接收，并与未进行优化的传感器实验结果进行了对比。通过对磁致伸缩传感器中螺线管结构的特别设计，实现了高阶模态超声导波的激励和接收，研究了激励信号周期数对人工凹槽缺陷检测结果的影响。(5)在Abaqus仿真软件中构建螺旋波纹管的计算模型，模拟超声导波在螺旋波纹管中的传播特性，并得到了含有环向裂纹缺陷时的仿真结果。而后采用自主研制的电磁声换能器在螺旋波纹管中激励和接收纵向模态导波，实现了对螺旋波纹管中人工裂纹缺陷的识别和定位。选用多物理场耦合分析软件对圆管的磁场分布规律进行有限元仿真，而后采用通过均匀包裹一层镍合金薄带的方式，提高了传感器的工作效率。(6)温度的变化会改变一些材料参数的数值，进而影响到超声导波在波导结构中的传播特性。首先从温度系数得到导波相速度和群速度随波纹参数的变化曲线，而后采用有限元仿真和试验两种方法来研究环境温度对超声导波传播特性的影响规律。更多还原

【Abstract】 In our country, more than83%of the electricity is supplied by the thermal powerplants. High pressure heater and condenser in power plant mostly use brass, carbonsteel or stainless steel tube as the heat exchange tube. Except hidden defects in theproduction and installation of these pipes and continuing to expand in the runningprocess, the use of the process can produce a variety of new defects in the pipelinewhich will be resulting to leakage, such as sediment induced corrosion, chemical gasinduced tube outer annular groove corrosion pits and pipe water impact abrasion.Nondestructive testing and evaluation in industrial pipeline using ultrasonicguided wave is becoming more and more mature. Ultrasonic sensor has been appliedin engineering practice and achieved good results. While contraposing boiler pipenetwork in large thermal power station which is the special detection object, thenondestructive testing technology for corrugated pipe which has complex structure ofthe heat exchange tube outer wall damage detection is relatively small. The influenceof ultrasonic guided wave propagation characteristics in the corrugated structure hasbeen researched based on theoretical analysis, numerical simulation and experiments.The main research contents are as follows.(1) Based on the classical wave dispersion equation in the free plate, corrugatedparameters in the corrugated plate has been imported into the dispersion equation, andthen the SH wave and Lamb wave dispersion equation of corrugated plate can beobtained. The dispersion equation is solving using the method of dichotomy, and thephase velocity and group velocity dispersion curves of guided wave propagationcharacteristics in flat and corrugated plate has been compared. The variation rules ofguided wave group velocity with corrugated parameters has been researched.(2) Derivation of free hollow cylindrical guided wave dispersion equation isobtained based on the classic, the bellows of torsional mode and longitudinal modeguided wave dispersion equation has been ratiocinated, and the sensitivity of theguided wave modes of wave parameters are compared. At the same time, the finiteelement simulation of propagation characteristics in corrugated structure has beenresearched on the platform of Abaqus software, and the actual changes of guidedwave propagation distance in corrugated structure are analyzed.(3) Analysis of ultrasonic guided wave phase velocity and group velocity dispersion curves when the material of longitudinal velocity and shear wave velocitiesare changed. For the change of wave parameters to the same degree, compareddifferent sensitivity to changes in corrugated board and corrugated pipe.(4) Through the analysis of relevant concepts of the magnetostrictive effect andultrasonic guided wave characteristics, magnetostrictive sensor are putting forwardoptimization scheme by multi-layer winding coil sensor on the basis of the existing.The longitudinal modes of ultrasonic guided wave excitation and reception, andcompared with past experimental results. Through the special design of the solenoidstructure of magnetostrictive sensors, the high order modes of ultrasonic guided waveexcitation and reception can be realized, and the artificial defects were detected.(5) Constructing the calculation model of spiral corrugated pipe in the Abaqussimulation software, and the simulation of guided wave propagation characteristics inspiral corrugated pipe with a crack has been shown. Then the electromagnetic acoustictransducer is developed in the spiral corrugated tube. The identification and locationof the artificial crack defects in spiral corrugated pipe by excitation and receivinglongitudinal mode guided waves. Analysis software for finite element simulation ofmagnetic field distribution of pipe selection multi-physics coupling, and the workingefficiency of sensor has been improved by coated with a layer of nickel alloy ribbons.(6) Changing temperature will inflect some material parameters, and then thepropagation characteristics of ultrasonic guided waves will affect in the waveguidestructure. The variation curve of guided wave phase velocity and group velocity withcorrugated parameters has been calculated from the temperature coefficient, and thenthe influence of environmental temperature on the propagation characteristics ofultrasonic guided wave has been researched by using the method of finite elementsimulation and experiments.更多还原