A comprehensive study of the magnetic concentrating sensor for the damage detection of steel wire ropes

Abstract

Magnetic flux leakage (MFL) method is an important way to detect the fault of steel wire ropes and the sensor for the collection of MFL plays a vital role in the damage detection. Among varied sensors based on MFL method, the magnetic concentrating sensor shows a lot of advantages in the detection of wire ropes. The use of the magnetic concentrator can assist the magnetic sensitive component to detect the MFL and reduce the number of the Hall components. The lift-off of the magnetic concentrating sensor can also be set to a feasible value which is easier to be ensured in the practical application. Although many researches on the magnetic concentrating sensor have been carried out, few of them have a comprehensive and thorough investigation, which should include the simulation analysis, the prototype design, the broken wire experiment and the comparison with other commonly used sensors. In this paper, a magnetic concentrating sensor is developed and compared with a Hall array sensor through both simulation and experiments. Firstly, the three-dimensional models of the magnetic concentrating sensor and the Hall array sensor are designed and their performance on collecting MFL is analyzed through finite element method (FEM). Secondly, the prototypes of the two kinds of sensors are designed according to the simulation results and their corresponding processing circuits are made. Finally, the effectiveness of the two sensors is evaluated by broken wire experiments with different rope diameters. The simulation and experimental results demonstrate that the magnetic concentrating sensor achieves a higher sensitivity and signal-to-noise ratio (SNR) than the Hall array sensor with less Hall components and simpler pre-processing circuit.

Keywords

• magnetic flux leakage
• magnetic concentration
• finite element method
• broken wires
• steel wire rope