scholarly journals Numerical study of contact wire tension affecting dropper stress of a catenary system

2021 ◽  
Vol 13 (3) ◽  
pp. 168781402199504
Author(s):  
Fan He ◽  
Dandan Guo ◽  
Liming Chen
Keyword(s):  
Tensile Stress ◽  
High Speed ◽  
Stress Amplitude ◽  
Numerical Study ◽  
Maximum Tensile Stress ◽  
Wire Tension ◽  
Contact Wire ◽  
Stress Changes ◽  
Response Equation ◽  
Catenary System

Dropper is the key component of in a catenary system and it is prone to fatigue fracture. Dropper stress directly affects the operation safety of high-speed railway. In this paper, a span of dropper in a catenary system is modeled to investigate the effects of contact wire tension on dropper stress. The response equation of contact wire and the theoretical equation of dropper stress are deduced. The initial and boundary conditions of each dropper are determined, and then the stress of each dropper is calculated by the finite difference method using a MATLAB program. The results show that the stress amplitude and the maximum tensile stress of the dropper decrease significantly with the increase of contact wire tension. When the tension is low, the stress changes of dropper near the load location experience three stages: instant rebound, attenuated vibration, and bending compression. However, the attenuation vibration stage disappears when the tension is increased to a certain extent. Therefore, the control of the vibration response of the contact wire can effectively reduce the stress amplitude and the maximum tensile stress of the dropper, so as to improve the working reliability of the dropper.

scholarly journals The Effects of Load Location on Dropper Stress in a Catenary System for a High-Speed Railway

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Fan He ◽  
Dandan Guo
Keyword(s):  
Tensile Stress ◽  
High Speed ◽  
Computer Code ◽  
Vertical Displacement ◽  
Maximum Tensile Stress ◽  
Free Boundaries ◽  
Sinusoidal Vibration ◽  
Contact Wire ◽  
Stress Changes ◽  
Load Location

In this paper, the effects of load location on dropper stress are studied. We treat contact wire as a beam element and derive its response equation and then deduce the stress equation of dropper. A computer code based on MATLAB is written to calculate dropper stress using the finite difference method. The results show that there are three stages during the period of the stress changes of dropper, including instant rebound, damped sinusoidal vibration, and bending compression. The shorter the distance away from a load is, the larger the vertical displacement of the dropper is, which results in the corresponding increases of its stress amplitude and the maximum tensile stress. The load location has a significant impact on the stress changes of dropper. Compared to the condition of the load in the middle, the load acting on the edge of contact wire could induce the larger tensile stress when both ends of contact wire are considered as free boundaries. Therefore, it is necessary to add supports at both ends.

scholarly journals Active Control of Contact Force for a Pantograph-Catenary System

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Jiqiang Wang
Keyword(s):  
Active Control ◽  
Contact Force ◽  
High Speed ◽  
Large Scale ◽  
Vibration Suppression ◽  
Numerical Study ◽  
Primary Objective ◽  
Geometric Framework ◽  
High Speed Trains ◽  
Catenary System

The performance of the high speed trains depends critically on the quality of the contact in the pantograph-catenary interaction. Maintaining a constant contact force needs taking special measures and one of the methods is to utilize active control to optimize the contact force. A number of active control methods have been proposed in the past decade. However, the primary objective of these methods has been to reduce the variation of the contact force in the pantograph-catenary system, ignoring the effects of locomotive vibrations on pantograph-catenary dynamics. Motivated by the problems in active control of vibration in large scale structures, the author has developed a geometric framework specifically targeting the remote vibration suppression problem based only on local control action. It is the intention of the paper to demonstrate its potential in the active control of the pantograph-catenary interaction, aiming to minimize the variation of the contact force while simultaneously suppressing the vibration disturbance from the train. A numerical study is provided through the application to a simplified pantograph-catenary model.

Dynamic performance of a pantograph–catenary system with consideration of the contact surface

2016 ◽  
Vol 232 (1) ◽  
pp. 262-274 ◽  
Author(s):  
Dongli Song ◽  
Yanan Jiang ◽  
Weihua Zhang
Keyword(s):  
Contact Force ◽  
Wear Surface ◽  
Contact Surface ◽  
High Speed ◽  
Shape Parameter ◽  
Dynamic Performance ◽  
System Dynamic ◽  
Contact Wire ◽  
Catenary System ◽  
Contact Strip

The influence of contact surface upon the dynamic performance of a pantograph–catenary system is a question that has been highlighted by the increasing use of high speed railways. Using the mode-superposition method, we establish a pantograph–catenary-coupled dynamics model with consideration of the contact surface; we analyse the characteristics of the contact surface based on a large amount of measured data; and we determine the characteristic parameters according to their influence upon the system dynamic performance. The results show that the contact wire irregularity contains a periodic component formed by gravity and a random component formed by wear, local assembly errors, hardpoints and the like. Periodic and low-frequency random irregularities mainly lead to the increase in contact force amplitude at peak points with wavelengths submultiple of the tension length, span or dropper spacing. On the contrary, high-frequency random irregularity has a great influence upon the amplitude of all frequencies and is the main factor leading to the deterioration of the system dynamic performance. The contact strip wear surface achieves quadratic function fitting, and we propose two characteristic quantities of this surface, namely, shape parameter A, and wear depth B. The wear surface of contact strip enhances the periodic characteristics of pantograph–catenary system of each span, leading to the amplitude increase of the contact force in frequency with span submultiple wavelength. The bigger the absolute value of the shape parameter, the poorer the dynamic performance. According to the criteria of the contact force eigenvalues, we determine the threshold value of the contact strip shape parameter A, and the contact wire irregularity amplitude of each frequency. The threshold given in this paper can be used in the condition assessment of parts, and make judgements on whether a servicing is needed, which is part of the technologies for informationisation and intelligent high-speed train health management.

scholarly journals New control approaches to improve contact quality in the conventional spans and overlap section in a high-speed catenary system

2019 ◽  
Vol 233 (9) ◽  
pp. 988-999
Author(s):  
Farzad Vesali ◽  
Habibollah Molatefi ◽  
Mohammad A Rezvani ◽  
Bijan Moaveni ◽  
Markus Hecht
Keyword(s):  
Analytical Model ◽  
Vertical Velocity ◽  
High Speed ◽  
Contact Point ◽  
Control Force ◽  
Linear Quadratic ◽  
Contact Wire ◽  
Optimal Controllers ◽  
Catenary System ◽  
Point Velocity

Continuous and quality contact between the pantograph and the catenary system is one of the major challenges for increasing the speed of electric trains. Compared to other studies, this paper has considered the catenary system as the main system and has assumed the pantograph as an excitation factor. Based on this, a controller has been applied on the contact wire, once at the last span and another time near the contact point of the pantograph. Results were compared with the conventional controllers that exert control force on a collector's head. Based on this, two different objectives were considered for the controller including ‘improvement of contact quality’ and ‘minimisation of the vertical velocity of the overlap point’. For this purpose, a full analytical model of the catenary system was presented and was verified using the relevant standards, and then three types of linear quadratic optimal controllers were added to the model with the two objectives mentioned above. The results of the study show that if the model aims to reduce the overlap point vertical velocity, contact quality will be improved. However, in case it aims to enhance contact quality, the velocity of the overlap point will not necessarily be reduced. Moreover, the contact point controller aiming at reducing the overlap point velocity outperforms other controllers and makes 71% improvement in contact quality in comparison with the no-controller case.

scholarly journals Strengthening of columnar-grained freshwater ice through cyclic flexural loading

2020 ◽  
Vol 66 (258) ◽  
pp. 556-566 ◽  
Author(s):  
Andrii Murdza ◽  
Erland M. Schulson ◽  
Carl E. Renshaw
Keyword(s):  
Cyclic Loading ◽  
Flexural Strength ◽  
Tensile Stress ◽  
Applied Stress ◽  
Stress Amplitude ◽  
Crack Nucleation ◽  
Back Stress ◽  
Maximum Tensile Stress ◽  
Reversed Cyclic ◽  
Fundamental Requirement

AbstractSystematic experiments reveal that the flexural strength of freshwater S2 columnar-grained ice loaded normal to the columns increases upon cyclic loading. Specifically, over the range of stress amplitudes 0.1–2.6 MPa the flexural strength increases linearly with increasing stress amplitude. The experiments were conducted upon both reversed and non-reversed cyclic loading over ranges of frequencies from 0.03 to 2 Hz and temperatures from −25 to −3°C. Strengthening can also be imparted through bending-induced creep. The fundamental requirement for strengthening is that the surface that undergoes maximum tensile stress during failure must have been pre-stressed in tension. Flexural strength is governed by crack nucleation. We suggest that the process is resisted by an internal back-stress that opposes the applied stress and builds up through either crystal dislocations piling up or grain boundaries sliding.

A Laboratory Model Study of a Railway Current Collection System

2007 ◽  
Author(s):  
Lars Drugge ◽  
Anders Lennartsson ◽  
Annika Stensson Trigell
Keyword(s):  
High Speed ◽  
Dynamic Properties ◽  
Current Collector ◽  
Laboratory Model ◽  
Contact Wire ◽  
Current Collection ◽  
Model Study ◽  
Stiffness Variation ◽  
Curved Track ◽  
Catenary System

A vital system on modern high-speed electric trains is the overhead catenary system and the pantograph current collector. As speed limits are increased, train operators and railway engineers need measures of system performance in a number of situations. In this work a laboratory model is built to study the pantograph behaviour on curved track running on a catenary system with large stiffness variation. The model is designed to be simple, yet exhibit the most characteristic dynamic properties of the real system. Another objective is the possibility to run the pantograph at speeds near the wave propagation velocity of the contact wire. The situation of several trailing pantographs, with even spacing, which excites the system to steady state, is considered. Effects of changes in design features such as tension in the contact wire and torsion and translation stiffness of components in the pantograph are studied for different speeds. The interaction is complex and the performance depends on the dynamic properties of both the catenary system and the pantograph. The results show that the pantograph configuration mainly affects the size of amplitudes in the system while the contact wire tension influences at which velocities large amplitudes and contact losses occur.

scholarly journals Multi-Body Dynamics Simulation of Hoisting Wire Rope and Its Stress Analysis

2020 ◽  
Vol 38 (3) ◽  
pp. 485-493
Author(s):  
Zhi Qin ◽  
Qing Huang ◽  
Hongrui Jin ◽  
Hongqian Xue
Keyword(s):  
Tensile Stress ◽  
Cross Section ◽  
Contact Stress ◽  
Stress Amplitude ◽  
Steel Wire ◽  
Geometric Model ◽  
Maximum Tensile Stress ◽  
Wire Rope ◽  
Dynamics Simulation ◽  
The Wire

As a key component of the hoisting system of the crane, the steel wire rope will bear a variety of loading actions such as stretching, bending, vibration and impact in the process of traction hoisting. Therefore, it is important to determinate the dynamic characteristics of the steel wire rope under complex loads and understand the stress-strain state to predict the risk of hoisting operation in advance. This article takes the bridge crane as the engineering background, first, a dynamic model of a steel wire rope lifting system based on ADAMS/Cable was established, and the dynamic stress spectrum of the steel wire rope during the lifting process was calculated and obtained. Secondly, by establishing the geometric model and finite element model of the wire rope, the tensile stress and wire displacement distribution of the wire rope and the contact stress between the wire rope and the pulley and the wires inside the wire rope are analyzed during the lifting process of the crane. The final results show that the instantaneous acceleration of the steel wire rope increases the maximum tensile stress of the steel wire rope by 37% compared with the stable lifting stage at the instant of starting the steel wire rope, causes an increase in the stress amplitude of the wire rope cross section, and the lifting process of the steel wire rope is accompanied by unstable vibration loads. The analysis found that the outermost cross-section of the steel wire rope's outer strand was subjected to the greatest stress, and its local maximum tensile stress amplitude was increased by 56% compared to the stable lifting stage. The contact stress generated by the contact between the steel wire rope and the pulley causes contact wear on the external and internal strands of the steel wire rope, and promotes fatigue fracture of the steel wire rope.

scholarly journals Numerical and parametric study of the yield stress limits of reinforcement bars in clay block masonry structures

2021 ◽  
Vol 14 (6) ◽  
Author(s):  
Orieta Soto Izquierdo ◽  
Márcio Roberto Silva Corrêa ◽  
Indara Soto Izquierdo ◽  
Iván Gómez Araújo
Keyword(s):  
Tensile Stress ◽  
Yield Stress ◽  
Parametric Study ◽  
Numerical Study ◽  
Maximum Tensile Stress ◽  
Masonry Structures ◽  
The Finite Element Method ◽  
Pull Out ◽  
Push Out ◽  
Brazilian Standard

abstract: The Brazilian Standard Structural Masonry considers for the maximum tensile stress (fs) of the reinforcements embedded in the grout in clay blocks with smooth surfaces several limits of the yield stress for the reinforcement (fyk). This work aims to analyze the limits of the yield stress of reinforcement bars in clay block masonry structures by numerical and parametric analysis in push-out and pull-out tests, varying the type of grout and reinforcement diameter. A numerical study was performed using a 3D-model with the DIANA® software based on the Finite Element Method. The parametric study confirmed that the limits obtained in this research for reinforcement diameter of 8 mm, 10 mm, 12.5 mm and 16 mm are in agreement with the limits specified by the Brazilian Standard, with exception of the 20 mm diameter, which limit was lower than indicated by the Standard. The tensile stress limits of the embedded reinforcement progressively reduce with increasing rebar diameter, being the failure is dominated by the bond strength of the block/grout interface.

UAV-LiDAR-Based Measuring Framework for Height and Stagger of High-Speed Railway Contact Wire

2021 ◽  
pp. 1-14
Author(s):  
Yixuan Geng ◽  
Fengjun Pan ◽  
Limin Jia ◽  
Zhipeng Wang ◽  
Yong Qin ◽  
...  
Keyword(s):  
High Speed ◽  
High Speed Railway ◽  
Contact Wire
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