| Due to the complex service environment,large size,complex bearing capacity and less accumulated operation experience of UHV transmission line fittings,some key fittings are prone to damage and destruction in the operation process,which will affect the safe operation of the line.The fittings prone to damage include tension-resistant plates,spacers and pre-twisted fittings.However,the parameters and material of the pre-twisted wire are the only factors affecting the grip strength of the pre-twisted tensioning wire clips.Therefore,this paper chooses the pre-twisted tensioning wire clip as the research object to determine the influence of the pre-twisted wire and its related parameters on grip strength.In this paper,the fastening characteristics of pre-twisted tensioning wire clips are analyzed from three aspects: theory,experiment and numerical simulation.Firstly,it will systematically introduce the types,characteristics and uses of pre-strung fittings,and then describe the geometric structure design theory of pre-strung tensioning clamp section and the spatial geometric structure design theory.In this paper,the influences of pre-twisted wire forming aperture,pre-twisted wire radius,pre-twisted wire pitch and pre-twisted wire total length on the fastening characteristics of tensioning pre-twisted metal fittings will be studied through experiments.The finite element software ABAQUS was used for numerical simulation of the pre-stranded tensioning wire clamp,and the ABAQUS/PDE module and Python language were used for parametric modeling.Based on the experiments,the influences of pre-twisted wire radius,pre-twisted wire pitch,number of pre-twisted wire pitch(total length)and tolerance(forming aperture)on the fastening characteristics of tensioning pretwisted metal fittings are studied under single wire,two wire and full wire conditions.Through the analysis of experiment and numerical simulation,we can get: keep advance radius of the hinge,and the tolerance of length of the hinge is constant,the single hardware and two wire hardware grip and decreases along with the advance of the hinge pitch,namely hardware grip strength and advance the hinge pitch is inversely proportional within a certain range,with the silk as the pitch increases;The gripping strength of singlewire,two-wire and full-wire fittings increases with the increase of tolerance while the pitch,total length and radius of pre-twisted wires remain unchanged,that is,the gripping strength of the fittings is proportional to the tolerance.When the pitch,total length and tolerance of the pre-twisted wire remain unchanged,the grip strength of the single wire and two wire fittings increases with the increase of the pre-twisted wire radius,that is,the grip strength of the full wire fittings is proportional to the pre-twisted wire radius,and the grip strength of the full wire fittings fluctuates within the range of 200 k N ～300k N.The gripping force of single wire,two wire and full wire increases with the increase of the total length of the wire,keeping the pitch,tolerance and radius of the wire unchanged,that is,the gripping force of the wire is proportional to the total length of the wire.With the pre-twisted wire radius,the total length of the pre-twisted wire,the tolerance and the number of the pre-twisted wire roots unchanged,the gripping strength showed an obvious upward trend when the pitch of the full wire was between 130 mm and 160 mm.When the pitch was between 160 mm and 205 mm,the gripping strength fluctuated around 310 k N,and its value changed little and tended to be stable. |
