| In order to overcome the difficulty that it is not easy to do nondestructive testing with high efficiency and low cost to steel pipes being used around kinds of fields, this topic carried out the research on theory and application of magnetostrictive ultrasonic guided wave nondestructive testing system. The system can be used for rapidly and globally inspecting over a large area of a structure. The magnetostrictive ultrasonic guided wave transducer was designed at first, then the hardware architecture based on FPGA and ARM processors was displayed. The test result in a steel pipe with 76mm diameters indicated that the system could detect 1% corrosion of the cross section.In the first chapter of the paper, the fact that steel pipe was used in large area and the detecting method were introduced firstly, then review of ultrasonic guided wave researching was discussed. Based on comparing of several ultrasonic guided wave NDT system available commercially, the significance and research aim of this topic was more clear. Finally, the research content of this topic was proposed, it’s very useful for the later research work.The second chapter studied the equation of motion in elastic solids with isotropic properties, and then by discussing the guided wave mode and disperse of hollow steel pipe model, it’s indicated that torsional mode T(0,1) was not disperse, then designed a magetostrictive transducer which could be used for wave direction control combined with signal processing. In the end, experiment data was showed us to determine the short time fourier transformation was useful in ultrasonic guided wave signal process. The three chapter designed magnetostrictive ultrasonic guided wave nondestructive testing system chart which mainly included magnetostrictive torsional ultrasonic guided wave transducer, embedded human machine interface, embedded control module, signal source module, power amplifier module, signal amplifier module, signal filter, AD converter. It also designed hardware system chart and several important hardware module were analyzed in detail, such as Li-Ion battery management, signal filter, ADC and DAC, wireless communication & positioning module. Finally, it analyzed some points in signal integrity designing.In the fourth chapter, the characteristic including spur property solutions of DDS were discussed, than analyzed and designed the logic chart of DDS, signal sampling and transmit. In the end, it gave the functions and implementation methods of embedded software including signal acquiring soft and signal analysis soft.The fifth chapter proposed system testing methods, such as environmental reliability test, EMC test and software test, then it taked an experiment in a steel pipe with 76mm diameter and 4mm thickness, the result showed us designed system was effective in detecting 1% corrosion of the cross section.In the sixth chapter, the comprehensive summary was made, and also questions in this research and further research work’s key points. |
PDF Full Text Request