Effect of Rail Vibration Absorber on Track Dynamical Behavior under High-Speed Moving Wheel Load

2014 ◽  
Author(s):  
Y. Zhao ◽  
X.B. Xiao ◽  
Z.F. Wen ◽  
X.S. Jin
Keyword(s):  
High Speed ◽  
Dynamical Behavior ◽  
Vibration Absorber ◽  
Wheel Load

Evaporation and Nucleate Boiling of an Individual Droplet on Surfaces

2005 ◽  
Author(s):  
X. D. Wang ◽  
G. Lu ◽  
X. F. Peng ◽  
B. X. Wang
Keyword(s):  
Heat Flux ◽  
High Speed ◽  
Bubble Dynamics ◽  
Imaging System ◽  
Dynamical Behavior ◽  
Saturation Temperature ◽  
Nucleate Boiling ◽  
Dynamical Process ◽  
Boiling Regime ◽  
Film Evaporation

A visual study was conducted to investigate the evaporation and nucleate boiling of a water droplet on heated copper, aluminum, or stainless surfaces with temperature ranging from 50°C to 112°C. Using a high-speed video imaging system, the dynamical process of the evaporation of a droplet was recoded to measure the transient variation of its diameter, height, and contact angle. When the contact temperature was lower than the saturation temperature, the evaporation was in film evaporation regime, and the evaporation could be divided into two stages. When the surface temperature was higher than the saturation temperature, the nucleate boiling was observed. The dynamical behavior of nucleation, bubble dynamics droplet were detail observed and discussed. The linear relationships of the average heat flux vs. temperature of the heated surfaces were found to hold for both the film evaporation regime and nucleate boiling regime. The different slopes indicated their heat transfer mechanism was distinct, the heat flux decreased in the nucleate boiling regime more rapidly than in the film evaporation due to the strong interaction between the bubbles.

Dynamic Performance Analysis on High-Speed Railway Continuous Girder Bridge

2011 ◽  
Vol 280 ◽  
pp. 186-190
Author(s):  
Shou Tan Song ◽  
Ji Wen Zhang ◽  
Xin Yuan
Keyword(s):  
High Speed ◽  
Moving Load ◽  
Damping Ratio ◽  
Dynamic Performance ◽  
Wheel Load ◽  
Dynamic Coefficients ◽  
Bridge Structures ◽  
Continuous Girder Bridge ◽  
Girder Bridge ◽  
Dynamic Performance Analysis

The dynamic performance of continuous girder under the train in a series of speed is studied through examples, and the main conclusions are given in the following. The resonance mechanism of continuous girder is similar to simply supported beam. The vehicle wheel load forms regular moving load series, which induces periodical action and resonance of the bridge. The damping ratio of bridge itself has less effect on the amplitude at the loading stage, but significant effects appear when the load departs from the bridge. The count of continuous spans also has less impact on the dynamic coefficients, so three continuous spans can be adopted for calculation and analysis. Span and fundamental frequency have significant influence on dynamic coefficients of bridge structures. To extend the span of the bridge structure can reduce the dynamic coefficient while keeping its frequency invariant. The fundamental frequencies of different bridges are corresponding to certain resonant speeds, which calls for the attention in the design.

scholarly journals Study on Multi-Degree of Freedom Dynamic Vibration Absorber of the Carbody of High-Speed Trains

2021 ◽  
Author(s):  
Yu SUN ◽  
Jinsong Zhou ◽  
Dao Gong ◽  
Yuanjin Ji
Keyword(s):  
Vibration Control ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Dynamic Stiffness ◽  
Degree Of Freedom ◽  
Vibration Absorber ◽  
High Speed Train ◽  
Dynamic Vibration Absorber ◽  
Multiple Degrees Of Freedom ◽  
Dynamic Vibration

Abstract To absorb the vibration of the carbody of the high-speed train in multiple degrees of freedom, a multi-degree of freedom dynamic vibration absorber (MDOF DVA) is proposed. Installed under the carbody, the natural vibration frequency of the MDOF DVA from each DOF can be designed as a DVA for each single degree of freedom of the carbody. Hence, a 12-DOF model including the main vibration system and a MDOF DVA is established, and the principle of Multi-DOF dynamic vibration absorption is analyzed by combining the design method of single DVA and genetic algorithm. Based on a high-speed train dynamics model including an under-carbody MDOF DVA, the vibration control effect on each DOF of the MDOF DVA is analyzed by the virtual excitation method. Moreover, a high static and low dynamic stiffness (HSLDS) mount is proposed based on a cam–roller–spring mechanism for the installation of the MDOF DVA due to the requirement of the low vertical dynamic stiffness. From the dynamic simulation of a non-linear model in time-domain, the vibration control performance of the MDOF DVA installed with nonlinear HSLDS mount on the carbody is analyzed. The results show that the MDOF DVA can absorb the vibration of the carbody in multiple degrees of freedom effectively, and improve the running ride quality of the vehicle.

Study on Derailment Mechanism and Safety Operation Area of High-Speed Trains Under Earthquake

2012 ◽  
Vol 7 (4) ◽  
Author(s):  
Liang Ling ◽  
Xinbiao Xiao ◽  
Xuesong Jin
Keyword(s):  
High Speed ◽  
Dynamical Behavior ◽  
Vehicle Speed ◽  
Vertical Force ◽  
Explicit Integration ◽  
Running Safety ◽  
Earthquake Motion ◽  
High Speed Trains ◽  
Wheel Loading ◽  
Safety Operation

In order to investigate the derailment mechanism and safety operation area of high-speed trains under earthquake, a coupled vehicle-track dynamic model considering earthquake effect is developed, in which the vehicle is modeled as a 35 degrees of freedom (DOF) multibody system with nonlinear suspension characteristic and the slab track is modeled as a discrete elastic support model. The rails of the track are assumed to be Timoshenko beams supported by discrete rail fasteners, and the slabs are modeled with solid finite elements. The system motion equations are solved by means of an explicit integration method in time domain. The present work analyzes in detail the effect of earthquake characteristics on the dynamical behaviors of a vehicle-track coupling system and the transient derailment criteria. The considered derailment criteria include the ratio of the wheel/rail lateral force to the vertical force, the wheel loading reduction, the wheel/rail contact point traces on the wheel tread, and the wheel rise with respect to the rail top, respectively. The present work also finds the safety operation area, the derailment area, and the warning area of high-speed trains under earthquake, and their boundaries. These areas consist of three key parameters influencing the dynamical behavior of high-speed train and track under earthquake. The three key influencing parameters are, respectively, the vehicle speed and the lateral and vertical peak ground acceleration (PGA) of an earthquake. The results obtained indicate that the lateral earthquake motion has a greater influence on the vehicle dynamic behavior and its running safety compared to the vertical earthquake motion. The risk of derailment increases quickly with the increasing of lateral earthquake motion amplitude. The lateral earthquake motion is dominant in the vehicle running safety influenced by an earthquake. While the vertical earthquake motion promotes jumping of the wheels easily, not easy is flange climb derailment. And the effect of the vehicle speed is not significant under earthquake.

Vibration response analysis of high-speed cylindrical roller bearings using response surface method

2020 ◽  
Vol 234 (2) ◽  
pp. 379-392
Author(s):  
Pravajyoti Patra ◽  
V Huzur Saran ◽  
SP Harsha
Keyword(s):  
Response Surface ◽  
Response Surface Method ◽  
High Speed ◽  
Dynamical Behavior ◽  
Roller Bearing ◽  
Interactive Effects ◽  
Response Analysis ◽  
Roller Bearings ◽  
Surface Method ◽  
Cylindrical Roller

The operating clearance in a bearing influences friction, load zone size and fatigue life of a bearing. Hence, an effort is made to investigate the effect of radial internal clearance on the dynamical behavior of a cylindrical roller bearing system with an unbalance present in the system. The differential equations representing the dynamics of the cylindrical roller bearings have been derived using Lagrange’s equations and solved numerically using the fourth-order Runge-Kutta iterative method. The nonlinear vibration signature has been analyzed due to the clearance and the same is represented by various tools like Acceleration-time plots, Poincaré plots and FFT plots. The approximation method is used to calculate the load distribution and deformation of the individual rollers located at a different position in the load zone, for a preloading/interference fit and positive internal clearance. A response surface method is used to analyze the severity involved in the system due to the combined effect of independent variables like rotor speed, radial load, and radial internal clearance. The observations presented here are not only useful to diagnose the bearing health condition with respect to parametric effects but also exhibit their interactive effects on bearing performance.

Dynamic Hybrid Modeling of the Vertical Z Axis in an HSM Machining Center: Towards Virtual Machining

2005 ◽  
Author(s):  
Giovanni Tani ◽  
Raffaele Bedini ◽  
Alessandro Fortunato ◽  
Claudio Mantega
Keyword(s):  
High Speed ◽  
Dynamical Behavior ◽  
Experimental Tests ◽  
Pneumatic System ◽  
Fem Modeling ◽  
Mechanical Structure ◽  
Machining Center ◽  
Feed Drives ◽  
Five Axis ◽  
Machine Head

The paper describes the dynamical real-time simulation of the Z axis of a five axis machining center for high speed milling. The axis consists of a mechanical structure: machine head and electro-mandrel, a CNC Control System provided with feed drives and a Pneumatic System to compensate the weight of the entire vertical machine head. These three sub-systems have been studied and modeled by means of: • FEM modeling of the mechanical structure; • an equation set to represent the main functions of the CNC; • an equation set to represent the functioning of the Pneumatic System. These different modeling sub-systems have been integrated to obtain the entire actual dynamical behavior of the Z axis. A particular analysis was developed to represent the friction phenomena by a specific analytical model. Experimental activity was developed to test and validate the different modeling sub-systems, and other experimental tests were performed on the machining center to compare simulation outputs with experimental responses.

scholarly journals A New Vibration Absorber Design for Under-Chassis Device of a High-Speed Train

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Yu Sun ◽  
Jinsong Zhou ◽  
Dao Gong ◽  
Wenjing Sun ◽  
Zhanghui Xia
Keyword(s):  
High Speed ◽  
Vibration Absorber ◽  
High Speed Train ◽  
Car Body ◽  
Multibody Dynamic ◽  
New Type ◽  
Rubber Component ◽  
Transfer Method ◽  
Optimal Stiffness ◽  
Disc Spring

To realize the separation of vertical and lateral stiffness of the under-chassis device, a new type of vibration absorber is designed by using the negative stiffness of the disc spring in parallel with the rubber component. To solve its transmission characteristics, harmonic transfer method was used. A rigid-flexible coupling multibody dynamic model of a high-speed train with an elastic car body is established, and the vertical and lateral optimal stiffness of the under-chassis device are calculated. The Sperling index and acceleration PSD of the vehicle with the new vibration absorber and the vehicle with traditional rubber absorber are compared and analyzed. The results show that, with the new vibration absorber, vehicle’s running stability and vibration of the car body are more effective than the vehicle with the traditional rubber absorber.

Influence of Conversion Deviation on Dynamic Performance of High-Speed Railway Turnout

2011 ◽  
Vol 474-476 ◽  
pp. 1599-1604 ◽  
Author(s):  
Rong Chen ◽  
Wang Ping ◽  
Xian Kui Wei
Keyword(s):  
High Speed ◽  
Detection System ◽  
Structural Characteristics ◽  
Dynamic Responses ◽  
Normal Operation ◽  
Foreign Matter ◽  
Wheel Load ◽  
High Speed Railway ◽  
Lateral Displacements ◽  
Railway Turnout

Railway turnout, an integrated mechatronics equipment of track technology, is one of key equipments that control the running speed of high-speed railway. During the conversion of turnout, the friction, inclusion of foreign matter and deficient displacement of conversion caused by its own structural characteristics may lead to severe wheel/rail impact. In order to study the influence of conversion deviation on safety and comfort of a train during passing the turnout, train/turnout dynamic model was applied. Taking No.18 turnout on a Passenger Dedicated Line (PDL) with 350km/h as a case study, when the train passed it, the influences of its deficient displacement and inclusion of foreign matter on the following dynamic responses were studied, i.e. wheel load distribution, wheel flange force, dynamic stress of rail, wheel unloading rate, derailment coefficient, as well as the lateral displacements of switch rail and nose rail, etc. Result shows that: (1) the deficient displacement and the inclusion of foreign matter will severely influence the normal operation of the turnout, so the safety and comfort during the train passing through turnout may be affected; (2) During the conversion of turnout, its deficient displacement should be controlled properly, and the foreign matter should be removed during routine maintenance, moreover, a reliable detection system should be set.

Dynamic Performance of Vehicle-Turnout-Bridge Coupling System in High-Speed Railway

2011 ◽  
Vol 50-51 ◽  
pp. 654-658
Author(s):  
Rong Chen ◽  
Wang Ping ◽  
Shun Xi Quan
Keyword(s):  
Relative Position ◽  
High Speed ◽  
Dynamic Performance ◽  
Dynamic Responses ◽  
Continuous Beam ◽  
Analysis Model ◽  
Wheel Load ◽  
System A ◽  
Coupling System ◽  
Contact Relation

In order to study dynamic behavior of vehicle-turnout-bridge coupling system, a vehicle-turnout-bridge dynamic analysis model is established by employing the dynamic finite element method (FEM). When No.18 crossover turnouts(with a speed of 350km/h) are laid symmetrically on the 6×32m continuous beam, influences of turnout/bridge relative position and wheel/rail contact relation in turnout zone on the system dynamic responses are analyzed. The result shows that: wheel/rail contact of turnout zone (especially the frog) has great effect on dynamic responses of turnout on bridge, thus the nose rail height of frog should be optimized to mitigate the wheel load transition and its longitudinal gradient. In terms of the 32m-span continuous beam, the best relative position is frog part of turnout arranged in the range of 1/8 and 1/4 of span.

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