Elastic-plastic modeling of metallic strands and wire ropes under axial tension and torsion loads

Elastic-plastic response is greatly involved in the failure of wire ropes. Based on the derivation of the local deformation parameters of individual wire, an analytical model characterizing the elastic-plastic behavior for both wire strands and multi-strand ropes is developed in this paper. Also, the contact status within a multilayered strand is carefully studied to achieve a full understanding of wire stresses. Details of the surface strain fields of ropes are captured by 3D digital image correlation (3D-DIC) technique and the results agree well with the prediction of the present model. Varying loading conditions are considered to analyze the yielding and failure behavior of wire strands. It is found that the rotation of ropes (no matter its positive or negative) will increase the overall stress level over the wire cross section, however, restraining the rope ends leads to higher contact stress. Increasing the helix angle moderately may be an effective method to reduce the contact pressure of strand wires. Our model provides straightforward prediction of the elastic-plastic response of wire ropes and proves an effective tool for rope design due to a great reduction of time consuming in numerical simulations.