Study On Mechanical And Frictional Wear Properties Of Braided Wire Rope Under Bending Condition

With the "14th Five-Year Plan" during the average annual growth rate of electricity consumption is increasing,combined with the imbalance of energy distribution in China,the stringing conductors in overhead transmission lines will be increasing,and braided wire rope as a traction tool of the necessary traction apparatus,is an important guarantee of the safe erection of the line.In the actual working conditions of braided wire rope by repeated tension,bending and twisting and other kinds of load,especially in the process of traction drum the force is the largest,and the most complex force condition,the long-term cycle of bending state leads to friction between the rope wire wear,when serious cause broken wire,and then due to the broken wire generated by the "domino effect" lead to braided wire rope service life reduction,greatly affect the stringing conductors in overhead transmission lines safety and stability.Hence,this paper takes YS9-8×19 braided wire rope as the research object,and carries out the research on the mechanical and frictional wear performance of braided wire rope under bending condition,in order to provide theoretical support for the structure improvement,design selection and life prediction of braided wire rope,which has essential theoretical value and engineering significance.The specific research content of the paper is as follows:The paper analyzes the structural characteristics of braided wire rope,applies the Frenet-Serret frame and Darboux vector in differential geometry to derive the geometric equations of rope wire centerline in bending state;on this basis,the expressions of curvature,torsion rate and contact angle of rope wire between strands are given,analyzes the change law of curvature and torsion rate of rope wire in bending state,and solves to obtain the contact angle of rope wire between adjacent strands.The research results show that,compared with the straight state,the bending state changes the position of the maximum value of rope curvature and torsion rate,and the range of change is significantly increased.Based on the expression of geometric characteristics of braided wire rope,the mechanical response model of rope strand under pure bending load is derived and compared with Costello’s theoretical model to verify the reliability of the model;drawing on Costello’s theoretical model of wire rope,the mechanical model of strand under tensile load is explored and the maximum stress of strand under pull-bend state is derived by using the superposition principle.On this basis,combined with the structural characteristics of braided wire rope,the mechanical response model of wire rope in tension-bending state is constructed.Considering the relative sliding between adjacent strands in bending state,the contact characteristics of the strands caused by friction are analyzed,and the distribution of the contact load between the wires and the internal force of the wire section along the wire axis is obtained,which provides a theoretical basis for the study of the friction and wear performance of braided wire rope.It provides a theoretical basis for the study of friction and wear performance of braided wire rope.It is found that the bending stiffness of the strand increases with the increase of the spiral winding angle;the contact load between the wires and the internal force of the rope section along the rope wire axis vary periodically when considering the frictional action.On the basis of the established geometric and mechanical models in the bending state to determine the test parameters,designed a rope wire contact angle adjustable to the grinding fixture,carried out a different contact angle between adjacent strands of wires,normal load and frequency of friction and wear test research,to explore the different test parameters on the rope wire friction and wear performance of the influence of the law.The test results show that the contact angle changes the contact state between the wires,the maximum wear depth increases with the increase of contact angle;the normal load affects the frictional wear performance by changing the size of the contact area between the wires,with the increase of normal load,the friction coefficient slightly decreases and the maximum wear depth increases;the frequency mainly affects the degree of material damage by the amount of oxide formed between the micro-convex body contact,the friction coefficient increases with the increase of frequency gradually increase,as the frequency increases from 2Hz to 6Hz,the maximum wear depth increases from 28.5μm to 64.6μm;the wear mechanism of rope wire is mainly adhesive wear,abrasive wear and oxidation wear,in the case of heavy load rope wire wear surface craters,material spalling wear characteristics,indicating that accompanied by fatigue wear,and with the increase in frequency oxidation wear more serious.