Analytical and finite element modelling of the elastic-plastic behaviour of metallic strands under axial-torsional loads

In this work a new formulation for modelling the elastic-plastic behaviour of metallic strands subjected to axial-torsional loads is presented. Simple and accurate cross sectional constitutive equations are derived, fully accounting for the evolution of plastic deformations in the wires, starting from a description of the internal structure of the strand. The proposed approach is suitable both for straightforward analytical calculations as well as for implementation into finite elements for the large-scale structural analyses of cable structures. A full three-dimensional (3D) finite element (FE) model, based on a parametric description of the strand internal geometry, is also developed. The results of both the FE model and the analytical formulation are validated with reference to a well-documented physical testing campaign and a well-established linearly elastic literature model. Additional analyses are then performed to carefully assess the validity of the proposed mechanical formulation, for a wide range of strand construction parameters, by means of systematic comparisons against the results of the 3D FE model and of a recent linearly elastic literature model.