Effect of lay direction on the mechanical behavior of multi-strand wire ropes

Abstract

The effect of lay direction of individual wires on the mechanical behavior of multi-strand wire ropes under axial loading is investigated based upon Love's thin rod theory. A typical 7 × 7 wire rope with an independent rope core is treated. Eight different lay directions of the wire rope are considered, in which the lay direction of the double helix wires is emphasized. Two theoretical models, namely the hierarchical calculation method and the direct calculation method, are used to calculate the internal forces of the rope. The numerical results based on the two models are assessed within the context of the finite element analysis of the multi-strand rope. It is highlighted that the result given by the hierarchical calculation method is closer to the FEM result. The mechanical responses on simple strand and multi-strand rope predicted by the two theoretical models are in good agreement with experimental data. The lay effect of wire rope and the effect of initial helix angle of individual wires on the internal forces of rope are analyzed in detail. It is demonstrated that the lay direction mainly affects the torque of the rope, but not the tensile force; while both the torque and the tensile force strongly depend on the initial helix angle of individual wires. It is implied that the global mechanical properties of wire rope can be adjusted with the lay direction and the helix angle of wires within the rope.