Study On Inspection Problems Of Multi-freedom Automated Ultrasonic Testing System

As the development of modern industry, especially airplane and spaceflight industry, the inspection to curved-surface and thick-section components becomes wider. The desire to precision, speed and of testing becomes higher. This paper points to the inspection problems of the system based on the multi-freedom automated ultrasonic testing system project. Pointing to the important influence of the position and pose of ultrasonic probe in the testing of the curved-surface components, according to the kinematics and errors of the system, the method of the error compensation is proposed by the reasons of error and the error model of the system to offer the exact parameters for the inspection of curved-surface components. Pointing to high speed scanning and the uniformity of inspection sensitivity in depth direction in the testing of the thick-section components, from the angle of optimization for the inspection method, study on the optimization for Dynamic Depth Focusing of ultrasonic phased array is carried out to provide the better method to the inspection of thick-section components.In chapter 1, firstly, the background and important significance of the dissertation were discussed. Secondly, the status of research on ultrasonic testing automation technology, the error compensation method of ultrasonic inspection robot and the application of ultrasonic phased array was introduced. Finally, detailed research contents and chapters arrangement were given.In chapter 2, the method of the routine ultrasonic inspection and the principle of ultrasonic phased array were discussed. Then, the structure of the multi-freedom automated ultrasonic testing system was depicted.In chapter 3, firstly, the kinematics of multi-freedom automated ultrasonic testing system was analyzed by D-H method to establish the relevant kinematics model. Secondly, the error model was established by the reason of errors and the principle of matrix differential coefficient. Thirdly, according to the characteristic of ultrasonic inspection, the method of conversely solving the parameters of the error model was proposed by the principle of multi-joint perturbation to achieve error compensation and improve the testing precision. Finally, the effectiveness of this error compensation method is testified by ultrasonic testing experiment of the curved surface airscrew component.In chapter 4, firstly, the principle and application of Dynamic Depth Focusing scanning in the inspection of thick-section components were discussed. Secondly, according to the characteristic of ultrasonic phased array, multi-focus transmission field method was obtained by Huygens acoustical principle to improve the uniformity of sensitivity in depth direction. The distribution of acoustic pressure in the axis direction was achieved by simulating the transmission acoustic field of linear array. Finally, the feasibility and effectiveness of this method is testified by DDF inspection experiments.In chapter 5, the retrospections and conclusions of this dissertation were summarized. Then, the possible research in future is presented.