| Steel wire rope has the advantages of high strength,reliable and durable,widely used in cranes,ports,coal mines,sightseeing ropeways and other occasions.Steel wire rope working environment is harsh,long time is extruded,wear,easy to lead to the loss of metal cross-sectional area of wire rope,and then lead to wire rope bearing strength reduced,directly affect the quality of wire rope and equipment running safety.Therefore,fast and accurate wire rope Loss of Metallic Area(LMA)for detection and quantitative analysis is essential.However,the main reasons for the inaccuracy,time consuming and inconvenience of the current wire rope LMA detection are: the detection sensor is not applicable to the actual application of the wire rope,the main flux detection method is not accurate for the slightly narrow damage width,the magnetic dipole model is not applicable to the calculation of the leakage field of the wire rope LMA,etc.Thesis uses ANSYS Maxwell and COMSOL electromagnetic simulation software to simulate and analyse the magnetic flux and leakage field distribution due to the LMA of wire rope,and on this basis,the detection method of wire rope LMA is investigated.The main elements and innovations of thesis are as follows:(1)On the basis of the actual wire rope model,the simulation model of the wire rope is simplified and the simulation results show that the change of magnetic flux in the detection coil due to the LMA of the wire rope is linearly related to the amount of its cross-sectional area loss,and there is also a non-linear relationship with the axial damage width.The rate of loss of wire rope LMA is proportional to the intensity of the leakage magnetic field at the damage,and the shape of the leakage magnetic field signal is related to the axial damage width,with the increase of the damage width,the leakage magnetic signal separates from a peak into two peaks that are gradually moving away from each other.(2)The simulation-based guidance of the PCB split coil design solves the problem that the traditional coil structure is not convenient to be applied in industrial practice.Using the designed PCB coil as a detection sensor and based on the theory of magnetic flux detection,the influence law of damage width on the main flux detection method is summarised,and based on this law a method to improve the main flux detection using axial magnetic flux density is proposed,and the LMA of the wire rope is quantified by least-fitting.Simulation analysis and experimental results show that the detection method proposed in thesis can quickly calculate the defective metal area loss value with an error within 1%,which meets the practical application.(3)A new method of wire rope cross-sectional area loss detection is proposed based on the solenoid model of wire rope leakage positive calculation model.Through the nature of magnetization of ferromagnetic materials,it is deduced that the leakage magnetic field strength B of the wire rope is equal to the product of the coefficient matrix K and the magnetization strength matrix M.The magnetization strength matrix of the wire rope is obtained by inversion of the Least Squares Method,and the damage parameters are characterized by the magnetization strength matrix,so as to realize the quantitative analysis of wire rope LMA. |
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