Research And Development On Magnetostrictive Guided Wave Sensor For Pipeline Crack Detection

Magnetostrictive guided wave detection is a kind of non-contact,long distance and fastultrasonic guided wave detection methods.it can be used in the nondestructive testingof oil or gas pipe and steel wire.it is one of the important research direction of newnondestructive testing technology.For the practical goals,this paper will developmagnetostrictive guided wave detection system, research magnetostrictive guided wavedetection sensor and experimental system, and research the pipe guided wave testingtechnology test.Firstly, the guided wave propagation characteristics and the function demand ofincentive power is discussed, and determined the structure guided wave incentive signalsource.The design method of power amplifier circuit,drive circuit, protect circuit isdiscussed. The control signal circuit based on FPGA chip is designed. And thesimulation results and debug output waveform is given.Secondly, the magnetostrictive torsion wave sensors is designed, put forward akind of nickel and coil torsion wave sensors structure, and do some defect detection test,and speed of the torsion wave is3303m/s. In order to realize incentive and receive ofmagnetostrictive longitudinal wave guide, based on the discussions of the loadingmethods of the bias magnetic field and the alternating magnetic field, the longitudinalwave guide sensor is developed.The test on a steel pipe indicates that this sensors canrealize the incentive and receiving of the guided wave, and speed of the longitudinalwave is5350m/s. A receiving sensor amplification filter circuit is also designed.Finally, some experiment were done based on the magnetostrictive guided wavedetection system. Discuss the guided wave of the different excitation condition, and putforward to a way used the amplitude and width of envelope of the wave packet toevaluation the guided wave, and inspection test on cracks with20mm,40mm,50mm inlength.the experiment show that: the more the cycles of pulse, the bigger guided wavesignal, but the wider the wave package width at the same time, the receiving voltage ofguided wave is proportional to incentive voltage the energy of the guided waves mainlyconcentrated in the frequency range with the incentive frequency as the centerfrequency.