The hockling of cables: a problem in shearable and extensible rod

In certain industrial processes, such as undersea cable laying, a very long rod subject to remote axial tension and torque can form a self-contacting loop. An increase in remote tension under a ®xed torque can draw the loop down in size until it becomes very small and then pulls apart. The very large local strains of the small loop can permanently damage the rod (e.g. through plastic deformation). In the cable laying industry, this process is known as hockling. This study uses the theory of linear elastic rods which can undergo shear and extensional deformations in addition to bending and twisting curvatures in order to solve approximately for the shape, force, and moments that occur during hockling. A new closed-form solution to the rod theory equations is developed and used to predict (at least approximately) the loops sizes and remote tensions that occur at the formation and pull apart of the contacting loop