Submodelling of Stress Concentrations in Helical Strand Cables within a Computational Homogenisation Framework

Generic helical strand cables are used in many engineering applications including overhead lines, suspension bridges and subsea mooring lines. Accurate failure prediction of these cables requires detailed assessment
of the stress concentrations at wire contact points. Finite element models of helical strands typically discretise wires into 3D solid elements. However, generating a suitably refined mesh capable of capturing stress concentrations leads to impractically large models. This paper proposes a submodelling procedure asa computationally efficient method to examine stress concentrations at wire contact points. A global model is developed first where computational homogenisation is employed to exploit the geometric periodicity of helical strands. A local finite element model of the critical contact region is subsequently constructed to determine the contact stresses. The submodel indicates stress concentrations are an order of magnitude larger than nominal wire axial stresses.