【作者】 张清华；

【导师】 陈铁群； 刘桂雄；

【作者基本信息】 华南理工大学 ， 测试计量技术及仪器， 2010， 硕士

【摘要】 无损检测技术对现代工业、制造业都非常有意义,各种无损检测技术都具有各自的优缺点,多种检测技术复合可以扬长避短。论文以“基于超声和涡流的复合式检测技术”为题,系统地研究超声与涡流复合机理、超声与涡流协同作用、超声涡流集成探头设计、基于D-S证据理论实现数据融合技术,对促进仪器科学技术、制造科学技术具有重要意义。研究工作得到广东省自然科学基金（200805611085）和广东省工业攻关项目（2006B12401001）的资助。论文阐述了复合式无损检测及数据融合技术在复合式无损检测技术中应用的国内外研究进展,对超声与涡流复合式检测机理、复合式无损检测数据融合理论等关键技术进行研究,提出对铁磁性产品进行全面检测的基于超声和涡流的复合式无损检测技术,设计集超声与涡流检测技术一体的复合式集成探头,结合数据融合手段,实现了复合式无损检测真正意义的复合检测技术。主要工作包括:①系统研究超声与涡流复合检测机理理论体系,所研究结论对于解决超声与涡流集成问题具有通用指导价值。打破现有单个无损检测技术不能完成对检测试件全面检测的局面,超声涡流两种普遍检测技术的结合,满足了大多数工业生产需求,具有普遍意义;②提出将平底超声直探头与涡流探头集成于一体的新型探头,打破了传统的简单物理层面上的技术复合,实现了超声和涡流真正意义上的技术复合,节约了制作成本、使用成本、检测成本,同时提高了检测速度、精度、准确度;③探索性地将超声与涡流检测参数进行协同分析,达到参数设置最优化,保证检测要求情况下,降低系统技术要求,实现成本降低的目的;④细分检测区域,分析各区域特征,针对不同的区域采用相应信号处理方法和缺陷模式识别法,在实现全面检测同时,提高检测速度、降低信号处理难度、节约成本;并将Manhattan距离法与D-S证据理论结合应用于构造超声与涡流置信度分配函数;⑤创造性地在Manhattan距离法中引入修正系数k。解决了当_ij小于1时,求出的置信度将大于1的矛盾。因此,本作者首次引入了修正系数k ,当发生_ij小于1的情况时,依然能得到p_ij的归一化出来结果。实验数据分析结果显示该方法的有效性。选用45#钢的焊缝作为检测对象,研究本课题基于超声与涡流复合式检测技术的有效性和可行性。焊缝板的超声涡流复合式检测实验表明,本课题提出的超声与涡流独立模式识别方法对超声与涡流独立检测区域效果很好,D-S证据理论在重叠区域的应用,一是可以降低{不明}的置信度;二是提高超声检测对于裂纹与未焊合的识别率。更多还原

【Abstract】 With the title Technique of Complex NDT Based on Ultrasonic & Eddy Current Testing, the thesis systematically studies fundamental theory of ultrasonic and eddy current complex testing. It include synergy of ultrasonic and eddy current testing, integrated probe designing which include ultrasonic and eddy current sensor, and the fundamental and key technology of data fusion based on D-S theory, et al. Complex NDT technique is developed, which has important academic value and practical significance in improving the technological development and application of NDT technology. This work is funded by the National Natural Science Foundation of China （No. 50805053）, The Natural Science Foundation of Guangdong province （200805611085）, Guangdong province key project （2006B12401001）.This thesis firstly analyzes the domestic and international research on technique of complex NDT and the applications of data fusion technology in complex NDT field. It also researches the key theory of data fusion and complex NDT technology based on ultrasonic and eddy current testing. Put forward the complex NDT technique based on ultrasonic and eddy current for ferromagnetic products. A integrated probe which include ultrasonic and eddy current sensor, combine with data fusion technique are promoted to a real sense of complex NDT technique. The main work includes the following parts:①Study theory of complex NDT technique based on ultrasonic and eddy current systematically. The conclusions have general guiding value for solving the problem of integrating ultrasonic and eddy current testing. It solves the problem of existing NDT techniques can not provide a comprehensive detection to test specimen. Combining ultrasonic and eddy current the two popular NDT techniques meet the needs of most industrial production which has universal significance.②It creatively develops integrated probe of ultrasonic and eddy current probe, breaking the traditional complex techniques which simply compound several testing techniques on physical aspects. It also reduces the production costs, using costs and testing cost, while increasing the detection speed and accuracy.③Firstly synergy analyzing ultrasonic and eddy current testing parameters to get optimization parameters to promote to reduce technical requirements which will reduce the cost meanwhile meet the detecting requirements.④It creatively divides detection area into three parts. According to each region character, it uses corresponding signal processing methods and pattern recognition methods to promote to extended test for workpiece meanwhile increasing the detection speed, easier the signal processing, saving cost.⑤It creatively combines Manhattan distance method with D-S evidence theory applying to construct ultrasonic and eddy current sensors confidence distribution function. Whit this method, we successfully obtained a variety of defects confidence distribution with ultrasonic and eddy current complex technique. It creatively introduce correction factor to Manhattan distance method, which solve the problem of when the value of d_ij less than 1. So, this thesis firstly using this correction factor k , when d_ij less than 1, we can still get the reasonable p_ij value. The experimental results show the effectiveness of this method.Using 45# steel weld as test object to study the effective and feasible of this complex NDT technique based on ultrasonic and eddy current testing.The experiments show that ultrasonic and eddy current pattern recognition methods using in each independent detecting regions well and the D-S evidence theory using in overlapping region, first can reduce confidence value of {unknown}, then, can improve the accuracy rating of ultrasonic testing with crack and lack of penetration defects.更多还原