Research Of The Wire Rope Nondestructive Testing Technology Based On Electromagnetic Method

The wire rope has been widely used in national product. Local Fault (LF) and Loss of Metallic Area (LMA) are the main contents of the wire rope nondestructive testing technology. The electromagnetic method is the most important method in the field of wire rope nondestructive testing technology. In the explorative and innovative research in this thesis, the testing mothods for Local Fault and Loss of Metallic Area have both been researched, based on the fundamental of electromagnetic testing method. Design of the testing system have been completed in this thesis.For the LF testing, the quantitative testing for the Local Fault which is a difficulty in the field of LF testing has been researched. The mathematical model of the leakage magnetic field of the broken wire has been established based on the theory of magnetic dipole in this thesis. The main factors affecting the leakage magnetic field have been found. The fitting function about the number of the broken wires and the peak-to-peak value of output signal has been found. And the peak-to-peak value of output signal has been collected successfully by the peak-to-peak value collecting algorithm based on dynamic baseline. The quantitative testing of the Local Fault has been achieved in a certain accuracy range.For the LMA testing, A magnetic bridge testing model based on the structure of single layer permanent magnet has been built. The linear relationship about the magnetic flux density in the bridge and the metallic cross-sectional area has been found. By the experiment that filling steel wires into steel pipe, the linear relationship about the hall output voltage and the wire rope cross-sectional area has been obtained. The main factors affecting the magnetic bridge testing model have been researched by the Ansoft finite element analysis method. Correctness of the methods has been verified through the LMA testing for actual rope.Design of the hardware and software of the testing system have been completed on the basis of the principle experiment in this thesis. For hardware system, the selection and layout of the hall sensor, the mechanism design of the testing porbe, the selection and circuit connection of the data acquisition card have been researched. For software system, according to the relavant national standards and industry standards, the physical condition of the wire rope has been estimated. Based on Vsisual C++6.0, some main software functions such as health estimating, real-time waveform display and failure alarm have been achieved.