Life prediction of a wire rope subjected to axial and bending loads

Analysis of the state of stress and strain of the wire ropes is fundamental in assessing mechanical strength; a comparison between different analytical formulations utilized to estimate the state of stress in the inner and external wires of a rope is presented in this paper. In particular, different approaches are used to design a model for axial force and bending moment. For this purpose, a rope used in a helicopter rescue hoist, subjected to swinging of the recovery hook, present in anomalous working conditions, is considered. The analytical results have been compared with experimental data obtained on the rope (modulus of elasticity, fatigue tests of the wire, rope bending fatigue tests) with the aim of making a critical comparison of the methods analysed and to allow a reliability fatigue life prediction for the component.