Fatigue Life Analysis Of High-speed Railway Catenary Dropper

The catenary is a direct power supply line for electric locomotives.When the high-speed train is in operation,the pantograph at the top of the locomotive is in direct contact with the contact wire to obtain continuous operation power.Dropper is designed to transmit vibration and force between contact wire and messenger wire,which is one of the key components for the safe operation of the catenary.In recent years,the frequent faults of pantograph-catenary system due to wire breaking and fracture have seriously affected Chinese high-speed rails' safe operation.Therefore,this thesis studies the influence of vehicle speed,dropper process parameters and pantograph-catenary system parameters on the fatigue life of the dropper,by analyzing the dynamic characteristics of the dropper when the pantograph is in dynamic contact with the contact wire.This thesis mainly completed the following work:(1)Dynamic analysis of pantograph-catenary system.On the basis of summarizing related literature home and abroad,finite element model of the catenary and lumped mass model of the pantograph were established respectively.Initial form calculation of the catenary model was completed by the negative sag method,and a contact unit was defined to couple the catenary and pantograph together.To extract the dynamic characteristic parameters of the dropper and provide data support for the subsequent fatigue analysis,the thesis changed train speed and pantograph-catenary parameters to perform dynamic simulation.(2)Fatigue life analysis method of dropper.Using single factor analysis method,3D solid model of the dropper was established and its static analysis was performed by changing key process parameters of the dropper.The failure principle of the dropper was analyzed,then the fatigue analysis method under the action of variable amplitude load and bending fatigue analysis theory were combined to determine overall design and method of the fatigue life analysis of dropper.This method provided further exploration of dropper's fatigue problem.(3)Fatigue life analysis of dropper under traffic.Utilizing rainflow counting method and Goodman line theory,the zero-average load spectrum of the dropper was compiled.Fatigue life of the dropper under six typical train speeds was obtained based on the Miner rule and the dropper's S-N curve.The results of the fatigue life of the dropper were analyzed from three aspects,including bending,speed,and installation position of the dropper.The results showed that the effect of bending on fatigue at high speed could not be ignored,and fatigue life values of the dropper in a span were symmetrical about the span's middle point,and the fatigue failure was the most likely to occur in the midspan dropper.(4)Analysis of factors affecting dropper's fatigue life.Single factor analysis method was used to study the influence of parameters,such as pretension of contact wire,messenger wire and stitch wire,lifting force,pan-head mass,pan-head stiffness and so on,on the fatigue life of the dropper,then the best values of each parameter were obtained,which provided reference for the design of the catenary.