The pantograph-catenary system bears the crucial task of supplying electrical energy to high-speed trains.However,as train speeds continue to increase,irregularities in the contact wire exacerbate vibrations within th...The pantograph-catenary system bears the crucial task of supplying electrical energy to high-speed trains.However,as train speeds continue to increase,irregularities in the contact wire exacerbate vibrations within the pantograph-catenary system,frequently triggering pantograph arcs.To delve deeper into the characteristics and erosion mechanisms of these arcs,this study employed high-speed cameras and photodiodes to precisely capture the evolution of the arc morphology and fluctuations in the arc intensity triggered by contact pair irregularities.By adjusting the current intensity,we further analyzed the impact of arc discharge on the friction and wear performance of the carbon strips,as well as their current-carrying efficiency.The study revealed that when the current is sufficiently high,the arc column of the old arc,which forms when the contact pair separates,connects with the arc root of the new arc that is yet to make contact,leading to the formation of a continuous arc.Additionally,under the same current conditions,the arc intensity prior to contact between tribo-pairs is notably weaker than that at the moment of separation.Furthermore,parameters such as the arc ignition rate,wear volume,and temperature are positively correlated with the current intensity.Severe arc discharge not only deteriorates the electrical performance of the system,causing current distortion,but also exacerbates the instability of system operation.Abrupt changes in the friction coefficient can serve as harbors of intense arcs between the contact pair.Arc erosion causes severe damage to current-carrying tribo-pairs,with ablation pits eliminating thermal cracks and pores and leaving behind numerous molten copper particles,significantly increasing the wear volume.This study provides strong support for understanding the arc erosion process caused by contact wire irregularities and the mechanisms underlying the abnormal wear of carbon strips.展开更多
Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3par...Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3particleswithsizesintherange5to200 μmonapin-on-flattribo-testerunderdryreciprocatingsliding conditions at room temperature. Based on the examined worn surface characteristics of both PTFE and 316L stainless steel (as a counterpart) and the analyzed coefficient of friction (COF) evolutions, the wear mechanism and particle size effect have been explored in detail. The results demonstrate that the abrasive size is the main contributing factor, which can drastically impact the wear mechanism and tribological properties of tribo-pairs. The COF exhibits different evolution characteristics (trends) for different abrasive sizes. For moderate particle sizes, the COF trends become more complicated and the most evident wear of the metallic counterpart is evident. The activity behaviors of abrasives are dominated by the particle size. Particles can becomes embedded in one of the tribo-pair materials to plough-cut the counterpart, thus causing two-body abrasive wear. The abrasives can also behave as free rolling bodies, which play the role of third body to realize three-body "PTFE-abrasive-316L"abrasion. When abrasives are involved in the wear process, both the wear rate and COF of the metallic counterpart increase, but the material removal rate of the PTFE is reduced. The results obtained can offer guidelines regarding the design and protection of seals.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52365022 and 52375181)the Gan-Po Talent Support Program of Jiangxi Province(No.20243BCE51035)+1 种基金the Natural Science Foundation of Jiangxi Province(Nos.20242BAB20196 and 20224ACB204012)the General Subject of State Key Laboratory of Performance Monitoring and Protection of Rail Transit Infrastructure(No.HJGZ2023208).
文摘The pantograph-catenary system bears the crucial task of supplying electrical energy to high-speed trains.However,as train speeds continue to increase,irregularities in the contact wire exacerbate vibrations within the pantograph-catenary system,frequently triggering pantograph arcs.To delve deeper into the characteristics and erosion mechanisms of these arcs,this study employed high-speed cameras and photodiodes to precisely capture the evolution of the arc morphology and fluctuations in the arc intensity triggered by contact pair irregularities.By adjusting the current intensity,we further analyzed the impact of arc discharge on the friction and wear performance of the carbon strips,as well as their current-carrying efficiency.The study revealed that when the current is sufficiently high,the arc column of the old arc,which forms when the contact pair separates,connects with the arc root of the new arc that is yet to make contact,leading to the formation of a continuous arc.Additionally,under the same current conditions,the arc intensity prior to contact between tribo-pairs is notably weaker than that at the moment of separation.Furthermore,parameters such as the arc ignition rate,wear volume,and temperature are positively correlated with the current intensity.Severe arc discharge not only deteriorates the electrical performance of the system,causing current distortion,but also exacerbates the instability of system operation.Abrupt changes in the friction coefficient can serve as harbors of intense arcs between the contact pair.Arc erosion causes severe damage to current-carrying tribo-pairs,with ablation pits eliminating thermal cracks and pores and leaving behind numerous molten copper particles,significantly increasing the wear volume.This study provides strong support for understanding the arc erosion process caused by contact wire irregularities and the mechanisms underlying the abnormal wear of carbon strips.
基金This work was supported by the National Natural Science Foundation of China(Nos.51775503 and 51875343)the Natural Science Foundation of Zhejiang Province(No.LY17E050020)+1 种基金the China Postdoctoral ScienceFoundation(Nos.2017M620152and 2018T110392)Jiangxi Natural Science Foundation of China(20171BCD40009).
文摘Abrasive wear is a common failure phenomenon that often limits the service life of sealing elements. Evaluation and comparison of the abrasion resistance of polytetrafluoroethylene (PTFE) were conducted using Al2O3particleswithsizesintherange5to200 μmonapin-on-flattribo-testerunderdryreciprocatingsliding conditions at room temperature. Based on the examined worn surface characteristics of both PTFE and 316L stainless steel (as a counterpart) and the analyzed coefficient of friction (COF) evolutions, the wear mechanism and particle size effect have been explored in detail. The results demonstrate that the abrasive size is the main contributing factor, which can drastically impact the wear mechanism and tribological properties of tribo-pairs. The COF exhibits different evolution characteristics (trends) for different abrasive sizes. For moderate particle sizes, the COF trends become more complicated and the most evident wear of the metallic counterpart is evident. The activity behaviors of abrasives are dominated by the particle size. Particles can becomes embedded in one of the tribo-pair materials to plough-cut the counterpart, thus causing two-body abrasive wear. The abrasives can also behave as free rolling bodies, which play the role of third body to realize three-body "PTFE-abrasive-316L"abrasion. When abrasives are involved in the wear process, both the wear rate and COF of the metallic counterpart increase, but the material removal rate of the PTFE is reduced. The results obtained can offer guidelines regarding the design and protection of seals.
