Prediction of the fatigue life of elevator wire rope using the Grey model GM (1,1)

This article presents a tensile testing method for elevator wire ropes to predict fatigue life using the Grey GM (1,1) model, based on the relationship between applied force and the service life of the wire rope. The model is constructed from testing data where forces are applied to the wire rope until failure or damage occurs. A tensile testing machine for elevator wire ropes was designed and constructed, with a 5-meter-tall steel frame structure. At the top, a driving machine consisting of a 7.5-horsepower motor was installed to pull a wire rope with a diameter of 10 millimeters. One end of the wire rope is attached to the lift car, while the other is connected to the counterweight, enabling two-level vertical movement. The tensile force simulation involved adding masses of 350, 450, 550, and 650 kilograms, which moved up and down and stopped abruptly. The peak tensile forces recorded in the wire rope were 3.641, 4.845, 6.666, and 7.873 kilonewtons, respectively. The predicted fatigue life of the wire rope corresponding to these forces was 1,347,302; 927,853; 638,988; and 440,055 cycles. The results show that the fatigue life of the wire rope decreases as the tensile force increases. Predicting the fatigue life of wire ropes is crucial for inspection and quality assessment of elevator ropes. It allows for estimating wear over time in accordance with the Ministerial Regulation on Standards for Safety Management, Occupational Health, and Working Environment concerning Machinery, Cranes, and Boilers B.E. 2564 (2021).