Torsional Stiffness of Twisted Wire Cables

In recent work, expressions were presented for the effective modulus of twisted wire cables consisting of a single lay. Results showed that axial load is nonlinear function of axial strain. However, the nonlinearity is quite small, and for most practical cases axial load can be treated as a linear function of axial strain. It is the purpose of this note to investigate the torsional stiffness of a single-lay wire cable and to determine how torsional stiffness varies with axial load and rotation of the cable. Since an actual cable or wire rope is composed of strands that are, generally speaking, single-lay wire cables, it is felt that a general theory of cables would require the torsional stiffness of each individual strand.