The Finite Element Simulation and Research on Magnetic Flux Leakage of Wire-Rope Defects
|School||Harbin Institute of Technology|
|Keywords||MFL Defect Finite element structure parameters|
Wire ropes are widely used in many industrial fields at present, it is so important in the respects of society and economy that its security must be assured. Most wire rope electromagnetic (EM) testing instruments which are available on the market produce the circumferentially integrated volume of magnetic flux leakage (MFL) along the rope, and are used to identify wire rope defects with a senior expert’s experience generally. This test method with one-dimensional signal can detect almost all serious defects by now, however, it’s far below a quantitative testing due to the complexity and diversiform of the MFL of defects and due to the loss of the circumferential information of it.On the basis of the full-scale analysis of history and current situation of wire rope non-destructive testing in the domestic and overseas country, a research direction has been proposed that simulation of the relationship between the quantitative characteristics of the parameters related to wire rope defects and MFL. The research was done in the respects as follows:Based on the finite element model, the relationship between the relevant parameters (defects’ width, defects’ depth, the lift-off distance, etc.) and magnetic flux leakage in theory were analyzed, and the theoretical relation was found.With the comparison on the influence of the one-loop, bi-loop, and multi-loop magnetization to the magnetic flux leakage, and some simulation study was also done, through comparing the uniformity of magnetization to steel wire rope and the range of magnetic flux leakage in the three different magnetization methods, the advantage of multi-loop magnetization is showed.After simulation of the relation between the relevant defects’parameters (defects’breadth, defects’depth, heeling angle of defects, defects’shape and defects’in-rope depth, etc.), and the rule was found, also the equation related is given, so as to offer some direction to quantitative inspection of defects.The influence of lift-off, pole distance and air-gap to magnetic flux leakage is also simulated with finite element method, after doing some analysis, the rule was found, and some related equations were gained, which offer the evidence to the design of the structure parameters.Based on the simulation of the permanent magnet excitation and structure parameters, the relationship between these factors and magnetic flux leakage was found, which will provide the reference to the quantitative detection of wire-rope defects.