【作者】 田武刚；

【导师】 罗飞路；

【作者基本信息】 国防科学技术大学 ， 仪器科学与技术， 2009， 博士

【摘要】 原位无损检测避免了装备和结构的拆卸、分解和安装,大大节省了检测时间和费用,集成化既减小了设备的体积更重要的是可充分发挥多种检测方法的优势,提高检测的准确率,它们都是通用测试领域重要的发展方向,开展相关研究对提高我军航空装备的保障能力具有十分重要的意义。本文立足于某型航空发动机九级篦齿盘和发动机叶片原位无损检测的工程实际需求,提出内窥和涡流检测集成化的思想,围绕集成化无损检测系统设计、内窥涡流集成化检测传感器设计、航空发动机九级篦齿盘和叶片的内窥涡流集成化原位无损检测、内窥涡流集成化检测的信息融合等问题开展了研究。主要研究内容与结论如下:(1)将嵌入式系统技术引入到无损检测中,研制了嵌入式内窥涡流集成化无损检测系统。设计了基于CMOS图像传感器的电子内窥镜,研究了内窥检测图像的增强处理方法,提高了内窥图像质量;研究了宽频高精度功率信号产生和涡流微弱检测信号的正交锁相放大处理等问题,完成了涡流检测硬件设计;采用模块化设计思想,设计了实时嵌入式检测软件。检测系统功能全面,智能化程度高,符合集成化发展的方向,与传统的无损检测仪器相比,具有体积小、重量轻、操作和携带方便等特点,可以满足航空发动机原位无损检测的需要。(2)针对现有的涡流检测传感器从结构和性能上无法满足某新型航空发动机关键构件九级篦齿盘原位无损检测要求的现状,提出了一种特殊结构的涡流传感器。该传感器激励线圈和检测线圈在空间上正交,利用有限元数值仿真方法对其参数进行了优化设计,其对九级篦齿盘裂纹缺陷检测灵敏度高、提离效应小,而且可以定量评估裂纹缺陷的深度;同时将该涡流传感器和电子内窥镜探头结合,设计了一种用于篦齿盘原位无损检测的内窥涡流集成化传感器。实验结果表明:内窥涡流集成化技术实现了对篦齿盘裂纹缺陷的原位无损检测,缺陷检测准确率和可靠性高。(3)针对目前航空发动机关键部件叶片的内窥检测结果需要人工判断和检测效率低等缺点,提出了一种发动机叶片内窥检测的缺陷自动识别算法。该算法采用数字图像处理技术提取叶片缺陷的形状特征和纹理特征作为分类识别的依据,设计了一种基于支持向量机的分类器实现对叶片内窥检测缺陷自动分类识别。实验结果表明:该算法对于叶片缺陷的识别正确率达到了85%。(4)从提高航空发动机叶片裂纹缺陷的内窥检测效果出发,基于前面的集成化思想,首先利用有限元数值仿真方法设计了一种提离效应很小的类匀强涡流传感器,该涡流传感器可以对叶片裂纹缺陷长度和深度进行定量评估,然后将其与电子内窥镜探头有机结合在一起,设计了一种航空发动机叶片检测专用的内窥涡流集成化传感器。实验结果表明:内窥涡流集成化技术实现了对航空发动机叶片缺陷的原位无损检测,检测结果的准确率和可靠性高。(5)基于D-S证据理论提出了一种用于航空发动机叶片内窥涡流集成化检测的信息融合算法。建立了内窥涡流集成化检测信息融合模型,构造了可信度分配函数,制定了决策规则,实现了内窥和涡流检测信息层的集成,提高了无损检测系统缺陷识别准确性。本文的研究成果已应用到航空发动机的日常维护和定期检测中,有效地减少了维护人员的工作量,缩短了现场检修时间,提高了检测效率。更多还原

【Abstract】 In-situ nondestructive testing avoids disassembling and assembling equipment or structures, so it saves plentiful time and cost. By integration both the volume of equipment is reduced and advantages of many methods are full used, so the defects detection precision is improved. In-situ nondestructive testing and integration are all important research directions in general measuring field. It has very important significance to exploit related research for building up maintenance support of our legionary aero equipments.This paper is based on the engineering practical requirement of the ninth level labyrinth disc and aeroengine blade in-situ nondestructive testing, and the thought of borescope inspection and eddy current testing integrated is proposed. The comprehensive research including nondestrctive testing system design, borescope and eddy current integrative sensor, ninth level labyrinth disc and aeroengine blade in-situ testing, integrative testing informationi fusion are presented. The primary results and conclusions are listed hereafter.(1) The embedded system technique is introduced to nondesturctive testing field. The embedded borescope and eddy current integrative nondestructive testing system is developed. The electronic borescope based on CMOS image sensor is designed. The borescope inspection image enhancement processing methods is researched. And the image quality is enhanced. The research of the power signal generator with broad bandwidth and accurate frequency, the orthogonal lock-in amplifier for eddy current testing weak signal, and and otherwise, is done. The hardware design of eddy current testing is achieved. The real time embedded inspection software is exploited using modularization design thought. The testing system is powerful, intelligent and accorded with integration development request. Compared with the traditional nondestructive testing instrument, it has excellent characteristics of small bulk, light weight, convenience for manipulation, portable design, etc. So it meets the requirements of in situ nondestructive testing for aeroengine.(2) This paper aims at the problem that the structure and performance of the existing eddy current sensors can’t satisfy the requirement of in-situ nondestructive testing for the ninth level labyrinth disc of an aeroengine, and an especial structural eddy current sensor is proposed. Its excitation coil and pickup coil are orthogonal in space. The parameters of the eddy current sensor are optimized using finite element simulation method. The eddy current sensor is very sensitive and has little lift-off effect to detect defects of the the ninth level labyrinth disc, and the cracks depth can be evaluated quantitatively. The eddy current sensor is combined with electronic borescope probe. A borescope and eddy current integrative sensor for the ninth level labyrinth disc in-situ testing is designed. The experiment results show borescope and eddy current integrative testing can in-situ detect cracks of the the ninth level labyrinth disc, and the defects detection precision and reliability are very high.(3) At present, the borescope inspection results are estimated artificially not automatically and the inspection efficiency is low. So an approach is propsed for aeroengine blades damage automatic estimation. The shape and texture characteristics of blades damage are extracted using digital image processing. A classifier based on support vector machine is designed for damage automatic estimation. The experiment results show the correct recognition ratio reaches 85%.(4) In order to improve the borescope inspection effect for cracks of aeroengine blades, based on integration thought, firstly a uniform eddy current sensor is designed using finite element emulational method, which has little lift-off effect, and can evaluate the crack length and depth quantitatively. Then, the uniform eddy current sensor is combined with electronic borescope properly, and a borescope and eddy current integrative sensor is designed for aeroengine baldes. The experiment results show the integrative sensor can in-situ detect defects of blades, and and the defects detection precision and reliability are high.(5) A method of borescope and eddy current integrative testing information fusion is proposed using D-S theory of evidence for aeroengine blades. The model of information fusion is established. Th belief assignment function is constructed. The decision-making rule is constituted. The integration of borescope and eddy current testing in information layer is carried out. It improves the correct flaw detection ratio of nondestrctive testing system.The main research results of this paper have been used in aeroengine for daily maintenance and periodic inspection, which reduces maintenance man’s workload availably and inspection time in field and the inspection efficiency is improved.更多还原