Research On Mechanical Properties Of Braided Wire Ropes Under Tensile Load

In recent years, the State Grid UHV construction developed rapidly. Tension stringing is the main form of power transmission line construction. Braided wire ropes are widely used as guide ropes and hauling ropes in the power system for tension stringing operation, because of its non-rotating characteristics. Braided wire ropes bear tensile, bending and torsion loads in the service process. Besides, the complexity of its structure makes the internal force state in braided wire ropes extremely complex after loading. In addition, the distribution and size of its stress after loading have an important influence on strength, failure, service life, safety use, design and manufacture of braided wire ropes. Therefore, it is extremely significant to study on the mechanical properties of braided wire ropes under tensile load.The paper taken YS9-8×19 braided wire ropes used commonly in transmission line tension stringing for the study, and carried out theoretical analysis, numerical simulation as well as tensile experimental study for the mechanical characteristics under tension load. The main research contents are as follows:(1) The strands position distributions in the cross-section of square-eight-strands braided ropes were analyzed. Combined the actual productive process of braided wire ropes, the forming hypothesis were proposed. After analyzing the structural characteristics and spatial winding relations of braided wire ropes, on the basis of applying differential geometry theory and spatial coordinate transformation principle, the spatial curve parametric equations of braided wire ropes were deduced, and finally, the mathematical model of braided wire ropes was established, which laid the good foundation for the geometrical properties analysis and geometric modeling of braided wire ropes under tensile load.(2) Based on the mathematical model of braided wire ropes, the theoretical derivations about curvature and torsion of strands and wires were conducted. The variation of the curvature and torsion are computed by MATLAB. Moreover, the influences of relevant parameters on the change of curvature and torsion characteristics were analyzed, which proposed guidance and advice for weaving of this class ropes, and provided a basis for mechanical properties analysis. Geometry model of YS9-8×19 braided wire ropes was established in Pro/E with the mathematical model. It’s a good foundation for the numerical simulation of braided wire ropes under tensile load.(3) Taken YS9-8×19 braided wire ropes for research object, and based on the construction of the geometry model, the finite element calculation model under tensile load was established by ANSYS Workbench. On the bases of study above, numerical simulation was conducted. Through analyzing numerical simulation results, the distributions of stress, deformation, contact stress and friction stress were obtained and studied, which showed a consistency with curvature and torsion analysis results. The effects of friction coefficient between the strands on the mechanical properties, stress, deformation,contact stress and friction stress were studied. Research conclusions could provide guidance for the practical usage of braided wire ropes.(4) The tensile tests of YS9-8×19 braided wire ropes were carried out with the utilization of wire ropes tensile testing machine. It was essential to measure the axial deformation of braided wire ropes under different tensile load in order to obtain force-deformation curve. Thus the experimental data were coompared with numerical results, which verifies the rationality of mathematical models and numerical simulation results. Meanwhile, analyzing the causes of deviation provided a reference to correct finite element model further.