Contact Wire Research Articles

Analysis of contact force and uplift of pantograph–catenary system in overlap section based on numerical simulations and experimental tests

This paper examines the dynamic performance of the pantograph passing through an overlap section of the catenary system, using a China’s high speed railway with the 4-span overlap as an example. The pantograph and catenary system are simulated as a lumped mass model and finite element model, respectively. The model is verified according to EN50318:2018. The model is also assessed against an experimental study of the contact force and uplift of contact wire at 300 km/h. Then the contact force and uplift of contact wire at the speed of 150–350 km/h are calculated. The research shows that when the pantograph passes through the overlap, the maximum contact force increases beyond 14%, the standard deviation of the contact force increases by more than 26%, and the increase of the vertical displacement exceeds 38%, which becomes more apparent with the increase of speed. Under the influence of aerodynamic force, when the running speed increases from 150 to 350 km/h, the mean contact force in the knuckle-downstream and knuckle-upstream orientation increase by 59.49% and 97.85%, respectively. As a result, the contact force and vertical displacement increase greatly when passing through the overlap section, which could affect the current collection quality.

Development of calculation method for melting amount mass of contact wire caused by melting and evaporation of molten metal bridge and arc generation

AbstractAs the mileage of the electric railway increases, the unevenness of the contact wire may separate the contact wire and the contact strip. Simultaneously, a disconnection arc discharge is generated by the molten metal bridge. This causes the contact wire to melt and evaporate causing it to break. A few studies have conducted experiments to prevent the contact wire from disconnecting. Based on the results thus obtained, they presented their hypotheses considering conditions sch as the current and time required for melting and evaporation of molten metal bridge and arc generation. In this study, a calculation method for the melting and disconnection phenomenon of the contact wire. Its mass increased when the currents from both sides of the contact wire were taken into consideration. Therefore, we obtained that the convection and radiation play an improtant role for calculation of the melting amount mass of contact wire.

Analysis of Dropper Stress in a Catenary System for a High-Speed Railway

When the pantograph slides over the contact wire at a high speed, there are cyclic stresses acting on droppers. The cyclic stresses are related with the fatigue life and fracture of the dropper. Thus, the stress calculation of the dropper is particularly important to ensure the safe operation of a train. In this paper, a simple model based on a span of five droppers is constructed. The contact wire is treated as a beam element and the vibration equation under a dynamic force is deduced. Then, the stresses are performed numerically using the finite difference method. The stress-time relationship under a dynamic force is obtained and compared with that under a constant force. The results show that there is a large shock effect during the deformation of dropper from straightening to compression and then bending. The dynamic force could cause much higher stresses than a constant force. It indicates that a dynamic force has a more significant impact on the stress value of dropper than a constant force.

Effect of Surface Microparameters on Contact Temperature of Sliding Electrical Contact

Sliding friction pair composed of contact wire and pantograph slide is the key component of train current collection system. Contact temperature is one of the important factors affecting the current-carrying and wear performance of the friction pair. In this article, sliding electrical contact experiments under different experimental conditions were conducted. Based on the measured contour curve of the slide surface, two fractal parameters of the slide surface were calculated by using the structure function method. And the effect of contact current, contact pressure, and sliding speed on the fractal parameters was discussed. A temperature field simulation model of sliding electrical contact considering two rough contact surfaces was established with COMSOL Multiphysics software. The effect of surface roughness and fractal parameters on contact temperature was analyzed by simulation. When other simulation parameters keep constant, the contact temperature first drops and then rises as the average roughness height of the contact surface increases. The average roughness slope of the contact surface has little effect on the contact temperature under high speed and strong current conditions. The contact temperature continuously decreases with the increase of fractal dimension or the decrease of fractal roughness. The conclusions can be used as a basis for further research on the contact temperature characteristics of the friction pair to improve its electrical contact performance.

Characteristics of droplet exudation on slippery liquid-infused porous surfaces considering thermal effect

The self-healing property of slippery liquid-infused porous surfaces ensures the continuity and stability of the liquid film on the surfaces. Therefore, how to promote the exudation and spreading of the lubricant is the key to realize the self-healing. In this study, a numerical model of lubricant exudation and spreading in micropores was established under the stimulation of the external temperature field. The morphological evolution of the meniscus and the distribution characteristics of the internal pressure during the exudation process were investigated. The influence mechanism of the thermal effect on the exudation and film formation on the porous surface was revealed. Results show that the formation process of lubricating film includes the lubricant exudation in the pores, the growth and spreading of microdroplets on the porous surface. In the lubricant exudation stage, the internal pressure of the fluid is negative. When the lubricant exudes to the edge of the pore, the internal pressure of the liquid changes from negative to positive. The three-phase contact wire is pinned at the edge of the pore and droplets are formed on the porous surface. When the droplet begins to spread, the internal pressure of the droplet decreases for the increasing of the meniscus curvature radius. The spreading velocity decreases gradually in the form of fluctuation under the combined action of the time-varying resistance and driving force. At higher wall temperature, the droplet surface tension and viscous resistance decrease, whereas the thermal-capillary force and driving force increase. Therefore, the higher the wall temperature, the greater the average velocity of the droplet spreading front, and the better the droplet spreading performance. Therefore, higher wall temperature can promote the droplet exudation and spreading on the surface, which is conducive to the self-healing of the lubricating film.

Mechanical behavior of entangled metallic wire mesh–silicone rubber interpenetrating phase composites under quasistatic compression

Interpenetrating phase composites (IPCs) with porous metal materials as the matrix and polymer materials as the reinforcement, which have a broad application prospect, have both the high strength of metal materials and the high energy absorption capacity of polymer materials. Entangled metallic wire materials are a new type of porous material with damping characteristics, which is an excellent choice for use as the matrix of IPCs. In the present work, a novel entangled metallic wire material–silicone rubber IPC is developed through the vacuum infiltration method with the entangled wire material as the matrix and silicone rubber as the reinforcing element. The mechanical properties (loss factor and tangent modulus) of the as-synthesized composites are characterized through compression tests. More specifically, the effects of key experimental parameters (strain) and material properties (matrix density, wire diameter, and anisotropy) on the mechanical properties of the composites are analyzed in detail. It is found that with the introduction of interfacial friction, the loss factor of the composites becomes higher than those of the pure entangled metallic wire material and silicone rubber; in particular, the tangent modulus is significantly enhanced. The complex structural characteristics of the proposed composite enable the loss factor and tangent modulus to exhibit a nonlinear relationship with the density over a range of displacement values. Moreover, the smaller the wire diameter is, the greater the loss factor of the composites is, while the tangent modulus exhibits the opposite trend. The unique wire contact form and preparation process endow the composites with nonlinear properties in the molding direction as well as pronounced anisotropy characteristics. HIGHLIGHT A novel interpenetrating phase composite is proposed. The composite quasistatic curve is nonlinear with excellent mechanical properties. The improved energy consumption properties are due to the interfacial friction. The increase in wire density greatly improves the elastic modulus of the composite. The composite is anisotropic with a better bearing capacity in the molding direction.

A Study on the Vibration Characteristics and Damage Mechanism of Pantograph Strips in a Railway Electrification System

This paper presents the vibration characteristics of a pantograph–catenary interaction in a rigid catenary system. Both computational simulation and laboratory tests are carried out to evaluate the frequency contents of pantograph strips. Based on the observation that irregular wear is characterized by the consistency between the pantograph strips’ wear pattern and the mode shape of their dominant modal frequencies, it is deducted that resonance occurs at the pantograph strip and the contact wire interface in the high frequency range. By applying damping treatment to the pantograph strip, and hence improving its damping property, a reduction of 7 dB in the total vibration level at the sliding contact can be achieved, as verified through field tests. It is also found that the worse the initial condition of the pantograph–catenary system, the more prominent the damping effects on the control of high-frequency vibration for irregular wear problems.

Localization Method and Finite Element Modelling of the Mid-Point Anchor of High-Speed Railway Distributed in Long Straight Line with Large Slope

In order to ensure the safe and reliable operation of a high-speed railway, the precise positioning of the mid-point anchor in the catenary is very important. In view of the two problems in the calculation of the mid-point anchor position of the catenary in a long ramp section, the calculation accuracy is low, and the calculation of the central anchor clamp position is lacking. In this study, the predetermined location of the mid-point anchor is chosen based on the mid-point anchor location principle and the line condition, and the range of the allowable error of the mid-point anchor setting is determined according to the predetermined position of the mid-point anchor. Secondly, by considering the impact of the line ramp and using the measured span length, the tension difference of the clue in the direction of the line is calculated. Then, the theoretical location of the mid-point anchor clamp is determined using the downhill component and the tension difference. Finally, the theoretical position of the clamp is corrected according to the setting of the dropper to obtain the corrected position of the clamp. An FEM (finite element method) of the catenary is established in ANSYS software to calculate the height difference between the messenger cable and the contact wire at the point of the mid-point anchor setting, and then the length of the mid-point anchor rope is obtained. Through the calculation of actual case data, the maximum value of the relative error of the location of the mid-point anchor obtained by this proposed method is very small compared with the actual position, which verifies the effectiveness of this method.

Analysis of the failure of a tramcar pantograph component through combined experimental approaches

Tramcar vehicles collect the required electrical power from the overhead contact line by means of a pantograph that carries a pan head with collector strips in sliding contact with the contact wire. Therefore, any failure of pantograph or of its components has a direct effect on the correct tramcar operation. The paper deals with a case of unexpected failures occurred on a connection element of the articulated frame of the pantograph of tramcars, causing the interruption of the service. No evidence of impact with the overhead line was detected, only it was clear that the immediate cause was the fatigue failure of a pin of the articulated connection between the upper and the lower arms of the frame of the pantograph. To clarify the original cause of the fatigue failure, an approach combining field measurements, laboratory tests and data processing to obtain the stresses acting on the pantograph failed components under service condition was adopted. It was found that the pantograph was subjected to high level of vibrations coming from the vehicle carbody, mainly due to the track irregularity. A comparative failure analysis was carried out and a solution to upgrade the component subjected to failure was proposed and implemented.

A new small sample test configuration for fatigue life estimation of overhead contact wires

Fatigue in railway overhead line electrification (OLE) contact wires can cause sudden catastrophic failures. The contact wire interacting with the pantograph both mechanically and electrically is subjected to tension and repetitive bending due to the pantograph contact force. Recently, fatigue failures of OLE have risen in prominence with increases in train speed. To address this a new fatigue test configuration has been developed. The study focuses on a method for testing the wire as a component enabling fatigue life evaluation of worn wires, or exploring the effect of installation damage, through component level evaluation of crack initiation and propagation. The new test configuration places a 400 mm-length contact wire in a combination of bending and pretension with realistic boundary conditions replicating service conditions for longer spans. The results are presented in a strain-life format to provide data for a wide range of potential service conditions.

Fretting wear evolution model of the metal filaments inside metal rubber

Metal rubber (MR) is a porous material which possesses macroscopic damping properties through the dry friction between the internal helical metal wires. Due to its complex topological structure, the research on the fretting wear of MR is rarely reported in the literature. In the present work, a double-body wear model of metal filaments is constructed by the master-slave composite method. The friction and wear conditions of the dynamic and static metal wires inside the MR are analyzed under different contact angles, loads, and vibration amplitudes. The results indicate that the wear area and volume of the dynamic wire under each working condition are significantly larger than those of the static wire, while the case for the wear depth is the opposite. After wear, the wires exhibit an obvious stress concentration phenomenon, which is distributed along the wire wear contour area, and the wear profile has a high sensitivity to the contact angle. In order to further investigate the difference in the wear degree of the static and dynamic wires inside the MR, the fretting amplitude is introduced to describe the wear scar area of the dynamic wire, the special wear scar area is reorganized regularly, and the wear volume of the wire is approximated by the regional combination, deriving and constructing a fretting wear evolution model suitable for MR wires. This evolution model can simultaneously predict the wear degree of dynamic and static wires, and its prediction accuracy is high. The prediction accuracy under each working condition is basically less than 10%; thus, the proposed model can be effectively applied to the fretting wear prediction of MR ultra-fine wire contact pairs. This work provides theoretical guidance for the life prediction and other aspects of MR materials.

커티너리 전차선로의 전력공급 고장 원인 상호간의 관계 분석

The catenary of the overhead single-wire country catenary is a contact wire that supplies power by mechanically and electrically contacting the pantograph (collection plate) of an electric rail vehicle whose position of power load changes. are using.BRIn this paper, power failures occurring in the transmission and substation facilities and distribution lines of railways, centered on domestic catenary lines for the past 5 years(from 2016 to 2020), are classified by the type of failure cause, and the cause of the failure is the type of the catenary line.(7 types): Model the relationship between design errors, material defects, construction defects, negligence in maintenance, work negligence, foreign substances, and parts aging into life cycle stages(construction⇒operation⇒disposal), and By applying the bathtub curve, which is a failure rate curve, the simulation results from a life cycle perspective derived a life cycle relationship between the causes of power failure in the overhead single-wire catenary.

Analysis of the pantograph’s mass distribution affecting the contact quality in high-speed railway

ABSTRACT The pantograph–catenary system is an essential device, transmitting electric energy to high-speed trains. The sliding contact quality between the collector strip and the contact wire must be strictly required, keeping the good current collection quality. In this work, the displacements of two independent tension wires are described by the Fourier sine-series expansions separately. The Lagrange equation of the second kind is used to establish the dynamic equation of the catenary, which is solved by the central difference method. A multi-rigid body dynamics theory based on the relative coordinates is adopted, describing the dynamic behaviour of the pantograph. Three types of mass distribution strategies applied to the main structure of the pantograph are discussed. The mass distribution of the main structure has a large effect on the pantograph–catenary interaction, and the maximum reduction ratio of the standard deviation (STD) of the dynamic contact force reaches −35.62%, which is significant for the pantograph’s structural optimization in high-speed railways.

Revealing fundamentals of charge extraction in photovoltaic devices through potentiostatic photoluminescence imaging

Revealing fundamentals of charge extraction in photovoltaic devices through potentiostatic photoluminescence imaging

Influence of the Catenary Distributed Parameters on the Resonance Frequencies of Electric Railways Based on Quantitative Calculation and Field Tests

High-order harmonic resonance is a key issue in the traction power supply systems (TPSS) of electric railways for safe operation. The effective evaluation of the resonance frequency is critical for taking measures to suppress harmonic resonance. In this paper, the influence of the distributed parameters of traction networks on resonance frequencies based on accurate calculation is proposed. The quantitative assessments of the distributed impedance and admittance are investigated. Furthermore, the theoretical calculation is directly verified using field tests at a high voltage level equal to 25 kV. The results show that the resonance frequencies of the TPSS are mainly affected by the distributed parameters, including the self-admittance and self-impedance of the contact wires, and the self-admittance of the positive feeders. In addition, the admittance connected in parallel has a greater effect than the series-connected impedance. The calculation method is also adapted to TPSS connected to renewable energy.

New methods for dynamically substructured system testing of a railway car pantograph

This study proposes new pantograph testing methods for railway pantograph/overhead catenary systems (OCS), based upon substructured testing consisting of a physical pantograph and a numerical OCS model. Hence, this work builds upon a previously presented work, (using the dynamically substructured system approach developed by Stoten and Hyde), which was conducted on a relatively simple mechanical structure in the Automatic Control and Test Laboratory (ACTLab), University of Bristol, UK. In this current paper, the dynamically substructured system (DSS) testing method is applied to a real shinkansen pantograph, using various actuator/DSS configurations that have been implemented at the Railway Technical Research Institute, Tokyo, Japan. In the first of these tests, a conventional servohydraulic actuated rig is used to represent phenomena due to the dropper-passing frequency. Resulting DSS test data are compared with those generated by a numerical simulation of the emulated system, i.e. the system to be represented by the DSS experimentation. Then, in the second set of investigations, the DSS method is used in conjunction with a new ‘rotational disc’ test rig that is arranged to be in dynamic interaction with the shinkansen pantograph contact head. This novel experimental system enables the investigation of dynamic interactions between the overhead catenary system contact wire and the pantograph head, due to span-passing. Again, results from this experimental investigation are compared with those generated by a purely numerical simulation of the emulated system.

The evolution law of the pantograph–catenary arc with the multi-stress coupled force analysis under the sub-atmospheric pressure strong-airflow condition

As the unique power entrance, the pantograph–catenary plays a vital role in providing traction power for high-speed railways. Along with the operational velocity of trains constantly increasing, the poor contact between the contact wire and the pantograph strip happens frequently due to the “rigid point” existing on the contact wire, forming the “off-line” phenomenon. The off-line phenomenon is normally accompanied by the pantograph–catenary arc occurring, which seriously threatens the safety of the power supply for the high-speed train. Nowadays, as some railways have been built in remote places at high altitude, the motion characteristics of the pantograph–catenary arc under the sub-atmospheric pressure with strong airflow are extremely different from the case under normal pressure. Herein, a pantograph–catenary arc experimental platform is built for observing the evolutionary process of the arc under the sub-atmospheric pressure strong-airflow condition. The impact brought from different air pressures and airflows on the arc is analyzed, as the experimental results show that the pantograph–catenary arc has different motion characteristics when the arcing process is at different stages. To further explore the reason resulting in the varying motion characteristics of the arc, a multi-stress coupled force analysis model is established, with the consideration of the influence of air pressure, wind load, thermal buoyancy, air resistance, arc self-magnetism, etc. From the perspective of force acting on the arc, the arc formation mechanism at the development evolutionary stages is investigated under sub-atmospheric pressure strong-airflow conditions, which lays a theoretical foundation for effectively restraining the pantograph–catenary arc.

Enhanced electrical, mechanical and tribological properties of Cu-Cr-Zr alloys by continuous extrusion forming and subsequent aging treatment

• A high performance Cu-1Cr-0.1Zr alloy was obtained by continuous extrusion forming and subsequent aging treatment. • The strengthening contributions of the grain refinement, dislocation and precipitation were quantitatively calculated. • The wear behavior was studied by examining the evolution of wear surface morphology and subsurface microstructure. • The microhardness (H), H/E r ratio and H 3 /E r 2 ratio were considered to gage the wear resistance of Cu-Cr-Zr alloy. As a promising material for the new generation of high-speed railway contact wires, the comprehensive optimization of the electrical conductivity, strength, hardness and wear resistance of the Cu-Cr-Zr alloy has received extensive attention. In this paper, a high-performance Cu-1Cr-0.1Zr alloy with an ultimate tensile strength of 599.1 MPa, a uniform elongation of 8.6%, a microhardness of 195.7 HV 0.2 and an electrical conductivity of 80.07%IACS was achieved by the continuous extrusion forming (CEF) and subsequent peak-aging treatment. The grain refinement strengthening, dislocation strengthening and precipitation strengthening are identified to be responsible for the excellent electrical and mechanical properties of Cu-Cr-Zr alloy. The wear behavior of Cu-Cr-Zr alloy was investigated by examining the evolution of worn surface morphology and subsurface microstructure. The microhardness ( H ) and reduced elastic modulus ( E r ) of the subsurface below the worn surface measured by nanoindentation were calculated to gage the tribological performance of Cu-Cr-Zr alloy. Results show that the continuously extruded and subsequently peak-aged specimen has the best wear resistance, which indicates that the tribological properties of Cu-Cr-Zr alloy strongly depend on its strength and hardness. It can be concluded that the CEF and subsequent aging treatment process provides a new and high-efficiency procedure for the continuous preparation of Cu-Cr-Zr alloys.

Development of Calculation Method for Melting Amount Mass of Contact Wire Caused by Melting and Evaporation of Molten Metal Bridge and Arc Generation

Development of Calculation Method for Melting Amount Mass of Contact Wire Caused by Melting and Evaporation of Molten Metal Bridge and Arc Generation

Test based finite element analysis of wire meshes

As fish farming is becoming more and more important worldwide, this ongoing project aims at the simulation and test-based analysis of highly stressed wire contacts, as they are found in off-shore fish farm cages in order to make them more reliable. The quasi-static tensile test of a wire mesh provides data for the construction of a finite element model to get a better understanding of the behavior of high-strength stainless steel from which the cages are made. Fatigue tests provide new insights that are used for an adjustment of the finite element model in order to predict the probability of possible damage caused by heavy mechanical loads (waves, storms, predators (sharks)).