Research On Detection Of Steel Wire LMA-Type Damagebased On Magnetic Characteristic Parameters

Wire ropes are often considered as ideal tension members due to their smooth and reliable operation,good bending performance,and good elasticity.They are widely used in elevator lifting,traffic,and mining.As the key components of tension equipment,the actual residual strength of wire rope is directly related to human life and production safety.The LMA-type damage is the metal sectional area loss type damage,which refers to the slow reduction of the effective metal breaking area in the axially long range of the steel wire rope,including the reduction of the cross-sectional area of the steel wire rope and the fatigue damage of the steel wire rope.LMA-type damage will reduce the actual residual strength of the wire rope,causing accidents.Therefore,it is of great significance to study the LMA-type damage and manufacture the detection device.The main research work is as follows:(1)Firstly,this paper starts with the characteristics of the steel wire rope,analyzes the damage form and damage characteristics of the wire rope,and explains the source of magnetic properties.The characteristics of the magnetization phase of the steel wire rope are summarized and the magnetic properties of the steel wire rope are studied.(2)From the theoretical analysis of the magnetic parameters of the residual strength of the steel wire rope,the fracture process of the steel wire rope is first analyzed,and then the internal and external causes of changes in the magnetic characteristics of the steel wire rope caused by fatigue damage are analyzed and described in conjunction with the changes in the internal structure of the steel wire rope.Based on the magnetic properties of the wire rope,the theoretical relationship between the LMA-type damage and the magnetic characteristics parameters was established.(3)Based on theoretical analysis and magnetic circuit law,the structure and parameters of the steel wire magnetic sensor are designed.Based on the structural characteristics of the steel wire rope and the excitation principle,the coil excitation method was selected as the excitation method.The exciter structure and excitation magnetic field were analyzed to make the number of excitation coils and excitation current certain.Sleeve type detection device was selected to establish a magnetic circuit,and the design parameters of the sleeve and magnetic pole were determined.The detection section uses a coil detection method as a detection method,and determines the number of coil turns and coil length based on the excitation section and the auxiliary section.Finally,based on the above analysis,a wire rope magnetic parameter detection sensor was fabricated,and the integrator processing circuit was designed and manufactured.(4)An experimental system for measuring magnetic parameters of steel wire ropes was designed and constructed,and corresponding wire rope test pieces were made for different kinds of damage of steel wire ropes.The steel wire rope test specimens with different degrees of damage were tested using the wire rope magnetic parameter testing system.The magnetic parameters of the test specimens were obtained.The magnetic parameters of each test specimen were calculated.Obtained and analyzed the relationship between magnetic parameters and degree of damage.The hysteresis loop of each test piece was drawn by gradually increasing the input current,and the relationship between the hysteresis loop and the remaining strength was obtained.Analyze the changing regularity of hysteresis loop.A theoretical model for inferring residual strength after wire rope damage was proposed,and the relationship between magnetic parameters of wire rope and remaining strength after damage was obtained.