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.