A Portable Composite Testing Instrument For Magnetic Flux Leakage And Guided Wave Testing

Composite non-destructive testing(NDT) technology can use a variety of detection methods to detect several types of defects, which is the development trend of NDT in recent years. At present, many kinds of instruments with a signal testing function are used in proper order to realize the composite NDT technology, which is not convenient. To slove the problem of inconvenience, this dissertation developes a portable composite testing instrument for magnetic flux leakage(MFL) and guided wave(GW) testing.First, the principles of MFL detector and GW detector are detailed analyzed. On this basis, a technical solution of the composite testing instrument is proposed, which is based on FPGA and USB. The technical solution realizes the integration of MFL and GW on chip level.Then, the hardware circuit is designed and the corresponding software of the composite testing instrument is developed. The hardware circuit makes the integration of MFL and GW on chip level come true, which includes public module, MFL sampling module, GW excitation module, GW sampling module and GW cache module. The modular design makes the intergrated instrument portable and small. The sofware is developed with a softcore called Nios II embedded in the FPGA chip, which is called the embedded design. Some logic modules used as data acquisition, data cache and communication are designed in the FPGA chip and controlled by Nios II softcore.Finally, the portable composite testing instrument for MFL and GW testing is developed, and its performance is tested on a steel pipe and a steel strand. The test results show that the composite instrument developed realizes the integration design of MFL and GW, which doesn't decrease the performance of MFL instrument or GW instrument.