Study On Embedded Ultrasonic Nondestructive Testing System With High-performance And Its Application

In order to accelerate the nationalization of the online ultrasonic nondestructive testing equipment with high performance to get rid of the situation of long-term dependence on imports, and improve the testing system's performance of reliability, real-time and quantification, an embedded multichannel ultrasonic nondestructive testing system with high performance was developed based on PXI bus by means of modular design strategy in this dissertation, which is supported by National Natural Science Foundation Project "Research on theory and practice of automatic online ultrasonic nondestructive testing with high performance based on rotating acoustic field (No.51175465)". Moreover, according to the quality control application of online ultrasonic testing for seamless tubes, a quantitative characterization method of flaw testing in seamless tubes based on model estimation & hybridized swarm intelligent algorithm, and an identification technique of near surface flaw based on Wiener filter & spectral extrapolation were carried out. The details of this dissertation were presented as follows:Chapter 1, the contribution of nondestructive testing technique to modern industry and the importance of automatic online ultrasonic nondestructive testing system for quality control of industry products were introduced. Meanwhile, the research status and its development trend of high performance UNDT system were summarized. Then the unsolved key technologies to improve the performance of reliability, real-time and quantification in ultrasonic nondestructive testing were discussed in order to point out the research direction of this dissertation.Chapter 2, according to the demands of functions and properties of ultrasonic nondestructive testing system with high performance, the general scheme of the UNDT system was proposed and the composition of this system was simply introduced.Chapter 3, according to the general scheme, the key measurement & control part including flexible ultrasonic transmitter & receiver, high speed A/D converter, real-time signal processer and communication unit, was studied in detail. Then ultrasonic transmit & receive board and digitalize, process & communicate board for ultrasonic testing channel with multi-functions were developed.Chapter 4, in order to realize the online quantitative analysis of seamless tubes, a new quantitative method based on model estimation and hybridized swarm intelligent algorithm was proposed. On basis of establishing layer model of the testing objects and determining the optimal target function by estimating the transfer function of this layer model using wave equation, the characteristic information was obtained by solving the optimal target function using hybridized swarm intelligent algorithm.Chapter 5, to solve the difficulty of near surface flaw identification, according to the basic model of ultrasonic echo, a new deconvolution method based on Wiener filter & spectral extrapolation was carried out in order to improve the resolution in time domain and the signal to noise ratio (SNR) of echoes from near surface flaws.Chapter 6, the main work and conclusions in this dissertation were summarized and the prospect for further research objects was put forward.