A new method to compute mechanical properties of a standing skyline for cable yarding

Abstract

Cable-based technologies are the backbone for logistics of timber or construction material on impassable terrain. In Central Europe, the use of standing skylines with pre-stressed, both-sided fixed-anchor cables and multi-span configurations with internal intermediate supports is common. To ensure a safe and cost-effective set-up for cable road operations, it is essential to identify and compute the properties of the skyline (e.g. load path, tensile forces). This task is challenging because it requires dealing with the non‐linear behaviour of the cable structure under the load and has to include all significant physical effects. Several approaches have previously been proposed as practical solutions, however not all physical effects were covered by those approaches, such as the inclination-dependent elastic prolongation of the cable or the longitudinal deflection of the sagging carriage. With our new proposed approach, we aim to close this gap of knowledge, and consider all relevant physical effects. We present a non-linear approach that is able to compute the properties of a wide range of standing skyline configurations, including those with additional cables. This approach offers an extensive solution and a flexible framework for considering individual configurations or particularities by adding equations to the equation system.

Calculation of Optimal Length for Skyline

“…The results of the calculation of the skylines are given in many works [3], [5,6], [9], [11]. However, it should be noted that some results were obtained for systems with small arrows of sagging (deflection) of the skyline (f max ≤ 1/20 l ) [8], [12], and the study mainly concerned specific tasks of designing cable rigging [8], [10], [13,14].…”

“…At present, there are tendencies in forest engineering practice to access such forested areas, where it is necessary to use skidding units, in which skyline deflection f max is greater than 5% of the span length l [9], [12]. Since such systems violate the fundamental assumptions of the existing methods for calculating skylines with small deflection arrows (e.g., uniform load distribution along the span; modelling the sagging curve of the holding cable with a parabola, etc.…”

“…In case of the uniform distribution of the vertical load (skyline self-weight) along the length of the skyline and neglection of deformations at the first stage (its longitudinal and transverse stiffness, temperature deformation, pliability of supports, etc.) [3,4], [7], [12], the shape of the sagging curve is described by a catenary [1], [9], [15] and Equations ( 1) and ( 2), for the system of flat rectangular coordinates x 0y 0 , which starts at point С (Figure 1):…”

“…In particular, the solution of this problem allows for the system with specific parameters to set the characteristic intervals, where one value of tension for the skylines corresponds to its two lengths (if T max > T opt ), one length (if T max = T opt ) or area where it is impossible to provide such tension in production conditions (T max < T opt ). This aspect is important to consider when improving theories of calculation of cable logging systems [3], [6], [9], as well as when developing systems of automated engineering design of cable equipment for forestry and timber production [3], [6], [8], [11], [13,14].…”

A Novel Two-Phase Approach to Forest Harvesting Optimization Using Cable Logging

“…The researchers suggest that the FEN simulation is useful for analyzing the tensile forces of the horizon. Going a step further in complexity, the article presented in [11] examines the forces affecting the extraction cables by adopting a nonlinear approach. This method provides a comprehensive solution, allowing adaptations based on specific configurations by adding equations to the existing system.…”