Technique Of Complex Ndt Based On Ultrasonic & Eddy Current Testing

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.