Research On Portable Ultrasonic Testing System For In-service Workpiece

Ultrasonic testing is a common nondestructive testing method for in-service workpiece. This paper, which is combined with the Zhejiang Provincial Natural Science Foundation, Zhejiang province science and technology plan as well as the actual application requirements, researches a set of portable ultrasonic testing system. The carbon fiber composite material, as the experimental object, the paper committed to solving in-service inspection of the coupling problem and key techniques of the testing system. The paper has carried out, respectively, methods of the in-service workpiece ultrasonic testing researching, portable ultrasound system designing, online analysis software designing, auxiliary coupling device and auxiliary motion inspection mechanism designing. These work can improve not only the convenience of the inspection of ultrasonic for in-service workpiece, but also its efficiency and accuracy. In addition, in this paper, the ultrasonic inspection signal processing of composite materials is researched deeply, the new method of noise and defects identification methods are proposed, and verified its effectiveness by experiments. The specific contents of each chapter are listed as follows:In chapter 1, the development and application of portable ultrasonic testing system, the ultrasonic testing for in-service and on-line signal analysis methods were introduced. There included the background, the significance of this investigation and the main contents of the paper.In chapter 2, the author researches ultrasonic testing method for in-service workpiece, from the applications, difficulties and requirements of in-service workpiece and ultrasonic inspection method of different types of composite workpiece defect, to choice of the basic method of in-service inspection. And the paper researched the method of analysis of ultrasonic signal processing.In chapter 3, the portable ultrasonic testing system and on-line analysis software are designed. It mainly includes the testing system’s principle, the overall design, the key module choice, the automatic ultrasonic inspection plan and the on-line analysis software function module design.In chapter 4, in order to solve the problem of ultrasound in-service inspection of coupling, stability, accuracy and inspection efficiency. In this chapter, the author designs two auxiliary inspection mechanism for in-service workpiece-the auxiliary coupling device and motion inspection mechanism.In chapter 5, there are three major parts, ultrasonic testing experiment using auxiliary coupling device, the composition of the composite ultrasonic signal and the method of removing noise, the recognition of the defect position. The method of noise reduction was studied, and the author put forward and optimized the combination method of EMD and wavelet threshold removing noise and verifies the validity of this method.The sixth chapter is the summary of the full paper, and discusses the prospects and the future research work.