Analysis of intermediate support cable logging systems

Graduation date: 1997The forest products industry often uses intermediate-support cable logging\ud systems to transport logs from the harvest site to a staging area. A method is presented to assist in the analysis and design of these cable systems. The method determines tensions in individual cables, forces on and stresses in the support trees, and the geometry of the system under load. Static equilibrium and cable length compatibility are used to generate a system of simultaneous equations. This system of coupled, non-linear algebraic equations is solved numerically using the Newton-Raphson algorithm. A good,\ud automated initial guess for the unknown quantities, based on the physics of the problem,\ud is provided. A model of an example intermediate support cable logging system is\ud analyzed by the proposed approach and the resulting behavior discussed. The method\ud includes the effects of catenary sag and elastic stretch in the cables, and elastic behavior in the support trees. Friction is ignored in the formulation. The catenary and elastic stretch methodologies for the cables are each demonstrated on a single cable span as well as on a demonstration cable system. The effect of the support tree flexibility and cable mass are found to be significant on the response of the cable logging system. The effects of elastic stretch in the cables is not found to be significant for the cable logging systems considered