Some considerations on the calculation of the secondary tensile wire stresses in multi-layer spiral strands under bending

Adequate models for the realistic calculation of multi-layer spiral strands at bending, are of continuing interest to the scientific community. On the one hand they pose, because of the rather complicated strand mechanics, a challenging problem; on the other, the knowledge of the wire stresses is of importance in various operating conditions of strands, such as strands over pulleys, lateral vibrations of strands, etc. A widely accepted model involves the consideration of secondary tensile wire stresses caused by the friction forces at the inter-layer interlaces of the strand wires. ln order to keep the analysis clear, the basic formulas for these stresses are usually deduced by taking into account the curvature of the strand wires in the straight strand. Because this curvature can vary significantly when the strand is bent, it is worth examining the influence on the secondary tensile wire stresses and subsequently on the bending stiffness of the strand. ln this paper it is shown, that although these stresses are influenced by the strand curvature, this influence on the bending stiffness of the strand and thus on the calculation of the strand deformation, can in most practical cases be neglected.

Author(s): Papailiou, K.O., Leider, M.G.