Responds of a helical triple-wire strand with interwire contact deformation and friction under axial and torsional loads

This paper aims to provide an analytical solution for describing the behaviors of a helical multi-wire strand under axial and torsional loads with the impacts of the local interwire contact. Both the interwire contact deformation and sliding friction are considered by using a theoretical approach, which divides the internal forces and moments of the multi-wire strand into two respective parts defined in two deformed configurations: one is related to the frictionless deformation state, and another is the friction deformation state of the multi-wire strand. The theoretical analysis has also conducted to understand the global responds of the strand, the local contact deformation and the friction contributions for a helical triple-wire strand. The overall axial forces, the twisting moments, and the stiffness components of the triple-wire strand with different helix angles under tensional and torsional loads are obtained The analytical results are in close agreement with the Finite Element (FE) predictions, validating the proposed analytical solution. The extended theoretical model and the proposed analytical solution well predict the responds of the helical triple-wire strand with a large range of helix angles (from 55° to 90°). The impacts of interwire contact deformation using Hertz and rigid contact theory, as well as with/without friction forces on the helical multi-wire strand behaviors have been discussed in details. The results show that the local interwire contact deformation and friction play a significant role on the strand responds as the helix angle decreasing.