Research On Stress Distribution Of Braided Wire Ropes Under Tensile Load

With the rapid development of the national power grid,the braided wire rope is widely used in cable tension construction because of its high strength and high torsion resistance.Because the construction environment is bad,and the load conditions in service life of the wire rope are very complex,the fatigue and breaking of the wire rope are common.The stress distribution of the braided wire rope under the tensile loads has a pronounced influence on the service life and strength of the wire rope.Increasingly attention has been paid to the mechanical modeling and failure mechanism analysis of braided wire rope.Due to the particularity of the structure,there is little research on the mechanics of braided wire rope.Therefore,it is necessary to establish the mechanics model of braided wire rope.What's more,the study on the stress distribution of the steel wire rope under the loads is to provide a theoretical basis for the failure mechanism analysis and structural optimization of the wire rope.Based on the parameter relationship,mechanical modeling,simulation,tensile test,broken wire and broken strand test of braided wire rope,the stress distribution under tensile load was studied,the specific contents are as follows:(1)According to the structural characteristics and parameter equation of braided wire rope,the geometric model was established and modified.Furthermore,the center line of the rope strand in the geometric model was projected.Based on the Ellipse four heart circle method,the expansion lines of rope were obtained.On this basis,the geometric parameters of braided wire rope were deduced with the help of CAD software.Through tensile test,the elastic modulus and shear modulus of strand were obtained.Based on the analysis of the curves of the curvature and torsion of the strands with centrifugal angle and pitch,the geometrical characteristics of the braided wire rope were further studied,which can lay the theoretical foundation for the mechanical analysis.(2)Based on the theory of elasticity and thin rods,the mechanical response of strands under tensile load was studied.The relationship between the axial force and the strain of the core wire,the inner and outer wire was obtained to establish the mechanical model of the straight rope.In this paper,the forces and deformation characteristics of the braided wire ropeunder tensile load were analyzed according to the expansion line of the strand.The relationship between the tensile load of the wire rope and the stress and strain of the strand was deduced to establish the mechanical model of the straight braided wire rope.Taking YS9-8×19 as an example,numerical calculation was carried out with MATLAB,and the variation of strain and stress with load was analyzed.(3)With the help of numerical simulation software,the finite element models of YS9-8×19 braided wire rope with frictionless and different friction coefficient were established.The stress and strain distributions of wire rope with frictionless and frictional were obtained by simulation to investigate the impact of friction force on the braided wire rope.In addition,the finite element simulation of braided wire rope under different tensile loads was carried out.In order to verify the validity of the mechanistic model,the simulation results were compared with the results of the theoretical calculation.Moreover,finite element models of braided wire rope with different pitch under the same load were simulated.Based on the analysis of stress and deformation of wire rope with the change of pitch,the optimal pitch was selected to provide theoretical guidance for engineering application.(4)The tensile tests under different loads was used to obtain the displacement curve of YS9-8×19 braided wire rope with tensile loads.The experimental results were compared with the theoretical results to verify the rationality of the mechanistic model.Besides,the breaking test of the braided wire rope sample was carried out to analyze the characteristics and position of broken wire and broken strand in order to investigate the existence of dangerous section.Compared with the theoretical and simulation results,the reliability of the stress distribution law of the braided wire rope under tensile load was verified.