919 Critical Wind Velocity to Overturn Railway Vehicle Considering the Difference of Aerodynamic Coefficient : Estimation by Using Multi-Body Software

2008 ◽  
Vol 2008.45 (0) ◽  
pp. 325-326
Author(s):  
Koichi SHIMADA ◽  
Katsuya TANIFUJI
Keyword(s):  
Wind Velocity ◽  
Railway Vehicle ◽  
Aerodynamic Coefficient ◽  
Coefficient Estimation ◽  
Critical Wind Velocity ◽  
The Difference ◽  
Multi Body

Hybrid Fatigue Analysis Method for Railway Carbody Structure

2008 ◽  
Vol 44-46 ◽  
pp. 733-738 ◽  
Author(s):  
Bing Rong Miao ◽  
Wei Hua Zhang ◽  
Shou Ne Xiao ◽  
Ding Chang Jin ◽  
Yong Xiang Zhao
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Hybrid Method ◽  
Dynamic Stress ◽  
Stress Test ◽  
Fatigue Analysis ◽  
Railway Vehicle ◽  
Analysis Method ◽  
Structure Dynamic ◽  
Multi Body

Railway vehicle structure fatigue life consumption monitoring can be used to determine fatigue damage by directly or indirectly monitoring the loads placed on critical vehicle components susceptible to failure from fatigue damage. The sample locomotive carbody structure was used for this study. Firstly, the hybrid fatigue analysis method was used with Multi-Body System (MBS) simulation and Finite Element Method (FEM) for evaluating the carbody structure dynamic stress histories. Secondly, the standard fatigue time domain method was used in fatigue analysis software FE-FATIGUE and MATLAB WAFO (Wave Analysis for Fatigue and Oceanography) tools. And carbody structure fatigue life and fatigue damage were predicted. Finally, and carbody structure dynamic stress experimental data was taken from this locomotive running between Kunming-Weishe for this analysis. The data was used to validate the simulation results based on hybrid method. The analysis results show that the hybrid method prediction error is approximately 30.7%. It also illustrates that the fatigue life and durability of the locomotive can be predicted with this hybrid method. The results of this study can be modified to be representative of the railway vehicle dynamic stress test.

A Fractional Derivative Model for Rubber Spring of Primary Suspension in Railway Vehicle Dynamics

2017 ◽  
Vol 3 (3) ◽  
Author(s):  
Dawei Zhang ◽  
Shengyang Zhu
Keyword(s):  
Fractional Derivative ◽  
Degrees Of Freedom ◽  
Excitation Frequency ◽  
Coupled System ◽  
Dynamic Responses ◽  
Viscous Force ◽  
Railway Vehicle ◽  
Spring Model ◽  
The Difference ◽  
Amplitude Dependency

This paper presents a nonlinear rubber spring model for the primary suspension of the railway vehicle, which can effectively describe the amplitude dependency and the frequency dependency of the rubber spring, by taking the elastic force, the fractional derivative viscous force, and nonlinear friction force into account. An improved two-dimensional vehicle–track coupled system is developed based on the nonlinear rubber spring model of the primary suspension. Nonlinear Hertz theory is used to couple the vehicle and track subsystems. The railway vehicle subsystem is regarded as a multibody system with ten degrees-of-freedom, and the track subsystem is treated as finite Euler–Bernoulli beams supported on a discrete–elastic foundation. Mechanical characteristic of the rubber spring due to harmonic excitations is analyzed to clarify the stiffness and damping dependencies on the excitation frequency and the displacement amplitude. Dynamic responses of the vehicle–track coupled dynamics system induced by the welded joint irregularity and random track irregularity have been performed to illustrate the difference between the Kelvin–Voigt model and the proposed model in the time and frequency domain.

Rule-Based and Expert Icing Screening Approaches for Wind Energy Measurements: Impacts, Methods, and Improvements

2011 ◽  
Author(s):  
James C. Harris ◽  
Carole A. Womeldorf
Keyword(s):  
Power Density ◽  
Wind Velocity ◽  
Lower Velocity ◽  
Rule Based ◽  
Multiple Sensors ◽  
The Difference ◽  
Visually Based ◽  
Wind Resource ◽  
Erroneous Data ◽  
Screening Approaches

Wind resource assessments produce hundreds of thousands of measurements every year. Before determination of the wind power density, a function of the velocity cubed, those values are screened to remove erroneous data points. Typical categories of erroneous data are sensor malfunction, tower shading, and icing. Identification of tower shading is a well established procedure dependent on the mounting direction of the sensor booms. Most instrument malfunctions are clearly extended flat lines and typically only affect one sensor at a time. Sensor icing of anemometers and directional vanes, on the other hand, can be subtle and affect more than one sensor simultaneously and can require an experienced evaluator’s assessment. Designation of icing results in the removal of lower velocity data. If too few points are removed the wind velocity will be underestimated, while if too many points are removed the wind velocity can be exaggerated, both of which can have a significant influence on the power density due to the cube effect. And experts frequently disagree. Much of this disagreement is driven by the difference between rule based approaches and operator judgment approaches. A comparison of different screening approaches for icing is described in this work. Three different rule-based approaches are compared against a visually-based expert determination that combines multiple sensors, including temperature, humidity, directional vanes and anemometers with several rule based approaches. Relative impacts of different approaches can affect from 1.09% for a visually-based expert approach to 5.03% for a rule-based standard deviation approach.

scholarly journals Electron-Induced Chemistry in the Condensed Phase

Atoms ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 33
Author(s):  
Jan Hendrik Bredehöft
Keyword(s):  
Gas Phase ◽  
Cross Sections ◽  
Condensed Phase ◽  
Theoretical Understanding ◽  
The Past ◽  
Long Time ◽  
The Difference ◽  
Molecule Interactions ◽  
Multi Body ◽  
Molecule Interaction

Electron–molecule interactions have been studied for a long time. Most of these studies have in the past been limited to the gas phase. In the condensed-phase processes that have recently attracted attention from academia as well as industry, a theoretical understanding is mostly based on electron–molecule interaction data from these gas phase experiments. When transferring this knowledge to condensed-phase problems, where number densities are much higher and multi-body interactions are common, care must be taken to critically interpret data, in the light of this chemical environment. The paper presented here highlights three typical challenges, namely the shift of ionization energies, the difference in absolute cross-sections and branching ratios, and the occurrence of multi-body processes that can stabilize otherwise unstable intermediates. Examples from recent research in astrochemistry, where radiation driven chemistry is imminently important are used to illustrate these challenges.

Analysis on Impact Loading at Rail Welds at High Speed

2008 ◽  
Author(s):  
Guangwen Xiao ◽  
Xinbiao Xiao ◽  
Zefeng Wen ◽  
Xuesong Jin
Keyword(s):  
Impact Loading ◽  
High Speed ◽  
Hertzian Contact ◽  
Railway Vehicle ◽  
Vehicle Speed ◽  
Explicit Integration ◽  
Normal Forces ◽  
Rail Irregularity ◽  
Multi Body ◽  
The Impact

When a railway vehicle passes through a track with different weld irregularities at high speed, the impact loading of the vehicle coupled with the track is investigated in detail using a coupled vehicle/track model. In this model, a half vehicle is considered and modeled as a multi-body system. In the track model, a Timoshenko beam resting on discrete sleepers is applied to model each rail. Each sleeper is modeled as a rigid body accounting for its vertical, lateral, roll motions. A moving sleeper support model is used to simulate the interaction of the vehicle and the track. The ballast bed is replaced with equivalent masses. The equivalent dampers and springs are used to replace the connections between the parts of the vehicle and track. In calculating the coupled vehicle and track dynamics, Hertzian contact theory and the creep force theory by Shen et al. are, respectively, used to calculate the normal forces and the creep forces between the wheels and the rails. The motion equations of the vehicle-track are solved by means of an explicit integration method. The weld rail irregularity is modeled by setting a local track vertical deviation at a rail weld joint, which is described with a simplified cosine function. In the numerical analysis the effect of the different wavelength, depth, the position of the welded joint in a sleeper span, and vehicle speed is taken into account. The numerical results obtained are greatly useful in the tolerance design of welded rail profile irregularity caused by damage and hand-grinding after rail welding.

Study on the Difference of Frontal Impact Response among People of Different Sizes

2010 ◽  
Vol 34-35 ◽  
pp. 111-116 ◽  
Author(s):  
Li Bo Cao ◽  
Chong Zhen Cui ◽  
Ning Yu Zhu ◽  
Huan Chen
Keyword(s):  
Human Body ◽  
Injury Risk ◽  
Simulation Models ◽  
Restraint System ◽  
Frontal Impact ◽  
Occupant Restraint System ◽  
Impact Simulation ◽  
The Difference ◽  
Human Body Models ◽  
Multi Body

In this article, seven frontal impact simulation models with same restraint system and different human body models were established through the use of multi-body kinematics software MADYMO. The injuries in head, chest and femurs of different human models and the differences of these injuries were analyzed in detail. The weighted injury criterion was adopted to evaluate the overall injuries of different human body models. The results shows that the injury risk of smaller human body is much higher than the taller human body, and existing occupant restraint system that protects the 50th percentile American occupant well protects other size occupant poorly.

Study Concerning the Effect of the Bushings' Deformability on the Static Behavior of the Rear Axle Guiding Linkages

2012 ◽  
Vol 245 ◽  
pp. 132-137 ◽  
Author(s):  
Vlad Totu ◽  
Cătălin Alexandru
Keyword(s):  
Rear Axle ◽  
Stationary Regime ◽  
Geometric Constraints ◽  
External Loading ◽  
Static Behavior ◽  
Compliant Joints ◽  
Rigid Model ◽  
The Difference ◽  
Guiding System ◽  
Multi Body

In this paper, we attempt to study the influence of the bushings (compliant joints) on the static behavior of the guiding system used for the rear axle of the vehicles. In fact, we are interested to determine the difference in behavior between the compliant model (with bushings) and the rigid model (bushings modeled as spherical joints) of the axle guiding mechanism. The static model, in which the car body is attached to ground, is a constrained, multi-body spatial mechanical system, in which the bodies are connected through geometric constraints, compliant joints, and force elements. The external loading is made by vertical forces applied to the wheels, in stationary regime. The study is made for the general groups of guiding mechanisms, with M=1 and M=2 degrees of mobility, by using the MBS (Multi-Body Systems) environment ADAMS of MSC Software.

Object-Oriented Modeling and Simulation of Railway Vehicle Systems

2010 ◽  
Vol 26-28 ◽  
pp. 900-904 ◽  
Author(s):  
Yong He ◽  
Guo Fu Ding ◽  
Yi Sheng Zou ◽  
Mei Wei Jia ◽  
Ming Heng Xu
Keyword(s):  
Software Package ◽  
Ride Comfort ◽  
Object Oriented ◽  
Simulation Software ◽  
Contact Forces ◽  
Railway Vehicle ◽  
Vehicle Systems ◽  
Hunting Stability ◽  
Multi Body ◽  
And Behavior

An object-oriented modeling method was proposed to develop a simulation software package named GVDS which could be used to predict some aspects of dynamic behavior of railway vehicle. The package based on multi-body dynamics mainly consists of three parts, an interactive pre-processor, the solver and an interactive post-processor. With UML, demands and structure of the software package are represented. By modeling of the geometry and behavior of each object, virtual prototype of railway vehicle is formed and by the simulation, the critical speed of hunting stability, wheel-rail contact forces and so on can be determined and the hunting stability, curving behavior and ride comfort can be analyzed and evaluated. Finally, some cases are simulated. The simulation results show the effectiveness of the proposed method.

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