Test And Development Of The Wireless ACFM Detection Instruments

With the development of economy, more and more special equipment is used in the production and living. Regular nondestructive testing is of great importance for security guarntee of production and living. And Alternating current field measurement(ACFM for short) is a new kind of nondestructive testing technologies combined of magnetic flux leakage testing and eddy current testing, which is used in testing defects on surface or near-surface of conductive workpieces and good for testing surface defects and wled defects. Because of non-contact detection, high accuracy, high efficiency, it is suitable for nondestructive testing of special equipment very much.However, The ACFM dectection instrument developed in domestic is usually combined by analog circuit and PC, which limits the flexibility of the dection of special equipment on special occasions. This paper presents an organic combination of embedded Android development and ACFM detection technology, and develops an ACFM detection instrument which is portable, wireless and easy-to-use. This wireless ACFM dection instrument solves some detection of special equipment on special occasions such as large-scale amusement equipment, the structure weld of bridges and furnace stays, etc. Which no only reduces the detection threshold, let ACFM detection become more easy and effective, but improves the safety of special equipment detections.Firstly, this paper elaborates the research status at home and abroad of ACFM.According to the principle of electromagnetic induction, elaborates the principle of ACFM detection technology and builds the mathematical model between the location and size of defects and ACFM detection signals,which confirm the relationship between defects and signals.Farther more we can find the position and the size of defects by observing the indicatrix and butterfly plot.And then, on the basis of requests for the detection of special equipment, designs the hardware circuits and software systems of the embedded wireless ACFM detection instrument by develop high speed integrated hardware circuit of FPGA and Android intelligent System.Finally, use this instrument to do some ACFM detection on different material test speciman which has some artificial discontinuities for proving the correctness ofmathematical model and verifying the veracity and reliability of this designed instrument on different excitation frequency. In addition, using ultrasonice testing and ACFM testing on pressure vessel verifies the veracity and reliability further.