Fatigue monitoring of coated steel belts by means of magnetic inspection

Coated steel belts (CSBs) are the primary load-bearing components of elevators. As a result, they may experience severe fatigue failure during their long-term service. In this study, a flexible fatigue fixture for CSBs is designed to simulate the CSB fatigue damage process for implementing a tensile fatigue test. The magnetic induction intensity signal on the surface of the CSB in a geomagnetic field environment is recorded using a high-precision weak magnetic sensor. Moreover, the CSB fatigue damage process is monitored online via the acquired magnetic induction intensity value. The fatigue test results indicate the following: the variation in the magnetic induction intensity signal curve can reflect the entire fatigue failure process when the CSB is under stress; the fatigue failure process of the steel wire inside the CSB does not occur smoothly as its progress occurs in stages; and the variation trend in the residual value between the magnetic induction intensity and fitting curves effectively indicates the degree of fatigue damage caused to the CSB.