scholarly journals Numerical analysis of beam rail bridges - impact factors in the vertical deflection

2017 ◽  
Vol 2017 (9) ◽  
pp. 11-17 ◽  
Author(s):  
Monika Podwórna
Keyword(s):  
High Speed ◽  
Equations Of Motion ◽  
Impact Factors ◽  
Vertical Deflection ◽  
Lagrange Equations ◽  
High Speeds ◽  
Rail Vehicles ◽  
Non Linear ◽  
Random Track Irregularities ◽  
The Impact

The impact factors in the vertical deflection obtained in dynamic analysis of BTT systems - bridged / track structure / high speed train (BTT) - are discussed. The BTT system is one of 5 bridges spanning from 15 m to 27 m, modelled as simply supported beams loaded by ICE-3 trains traveling at high speeds. The two-dimensional, physically non-linear BTT model includes: viscoelastic suspension of rail vehicles on two independent axle bogies and non-linear one-sided wheel-rail contact springs according to Hertz theory, access zones for composite construction. The BTT system was divided into subsystems loaded with vertical interactions transmitted by elastic or viscoelastic and physically linear or nonlinear constraints. Using Lagrange equations and internal aggregation of subsystems, discretised according to the finite element method, matrix equations of motion of the subsystems were obtained, with explicit linear left sides and nonlinear implicit right sides, which were integrated numerically using the Newmark method with parameters βN=1/4, γN=1/2. The analysis focus on the effect of random track irregularities on the dynamic response of BTT systems.

scholarly journals Impact of a Multiple Pendulum with a Non-Linear Contact Force

Mathematics ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 1202
Author(s):  
Dan B. Marghitu ◽  
Jing Zhao
Keyword(s):  
Kinetic Energy ◽  
Contact Force ◽  
Equations Of Motion ◽  
Linear Equations ◽  
Kinematic Chain ◽  
Double Pendulum ◽  
Lagrange Equations ◽  
Non Linear ◽  
Impact Kinetic Energy ◽  
The Impact

This article presents a method to solve the impact of a kinematic chain in terms of a non-linear contact force. The nonlinear contact force has different expressions for elastic compression, elasto-plastic compression, and elastic restitution. Lagrange equations of motion are used to obtain the non-linear equations of motion with friction for the collision period. The kinetic energy during the impact is compared with the pre-impact kinetic energy. During the impact of a double pendulum the kinetic energy of the non-impacting link is increasing and the total kinetic energy of the impacting link is decreasing.

scholarly journals Speed Effects on Inherent Rotating Frequency of Motorized Spindle System

2011 ◽  
Vol 2-3 ◽  
pp. 900-905 ◽  
Author(s):  
Bo Wang ◽  
Wei Sun ◽  
Kun Peng Xu ◽  
Bang Сhuan Wen
Keyword(s):  
Centrifugal Force ◽  
High Speed ◽  
Impact Factors ◽  
Motorized Spindle ◽  
Spindle System ◽  
High Speeds ◽  
Radial Stiffness ◽  
Bearing Stiffness ◽  
Coupling Factors ◽  
The Impact

The paper determines the impact factors of high-speed spindle system including the centrifugal force, gyroscopic moments and the bearing stiffness softening, etc, then builds the general spindle-bearing FEM considering high speeds. Taking a motorized spindle as example, the effect of centrifugal force, gyroscopic effect, the radial stiffness and the coupling factors are analyzed qualitatively and quantitatively. Finally the research shows the variations of bearing radial stiffness, centrifugal force and gyroscopic moments have a significant effect on dynamics of spindle system in high speeds, while modeling the high speed spindle system, above factors must be considered.

The High Speed Influence on Inherent Frequency of Motorized Spindle

2013 ◽  
Vol 779-780 ◽  
pp. 916-920
Author(s):  
Bo Wang ◽  
Kun Peng Xu ◽  
Bang Chuan Wen
Keyword(s):  
Centrifugal Force ◽  
High Speed ◽  
Impact Factors ◽  
Motorized Spindle ◽  
Spindle System ◽  
High Speeds ◽  
Radial Stiffness ◽  
Inherent Frequency ◽  
Bearing Stiffness ◽  
The Impact

The paper determines the impact factors of high-speed spindle system including the centrifugal force, gyroscopic moments and the bearing stiffness softening, and builds the general spindle-bearing FEM considering high speeds. Taking a motorized spindle as example, the effect of centrifugal force, gyroscopic effect, the radial stiffness and the coupling factors are analyzed qualitatively and quantitatively. Finally the research shows the variations of bearing radial stiffness, centrifugal force and gyroscopic moments have a significant effect on dynamics of spindle system in high speeds, while modeling the high speed spindle system, above factors must be considered.

scholarly journals Examining partial proportional odds model in analyzing severity of high-speed railway accident

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Jing Wang ◽  
Yinghan Wang ◽  
Yichuan Peng ◽  
Jian John Lu
Keyword(s):  
High Speed ◽  
Proportional Odds Model ◽  
Impact Factors ◽  
Proportional Odds ◽  
High Speed Railway ◽  
Severity Level ◽  
Content Type ◽  
Factors Affecting ◽  
Partial Proportional Odds Model ◽  
The Impact

Purpose The operation safety of the high-speed railway has been widely concerned. Due to the joint influence of the environment, equipment, personnel and other factors, accidents are inevitable in the operation process. However, few studies focused on identifying contributing factors affecting the severity of high-speed railway accidents because of the difficulty in obtaining field data. This study aims to investigate the impact factors affecting the severity of the general high-speed railway. Design/methodology/approach A total of 14 potential factors were examined from 475 data. The severity level is categorized into four levels by delay time and the number of subsequent trains that are affected by the accident. The partial proportional odds model was constructed to relax the constraint of the parallel line assumption. Findings The results show that 10 factors are found to significantly affect accident severity. Moreover, the factors including automation train protection (ATP) system fault, platform screen door and train door fault, traction converter fault and railway clearance intrusion by objects have an effect on reducing the severity level. On the contrary, the accidents caused by objects hanging on the catenary, pantograph fault, passenger misconducting or sudden illness, personnel intrusion of railway clearance, driving on heavy rain or snow and train collision against objects tend to be more severe. Originality/value The research results are very useful for mitigating the consequences of high-speed rail accidents.

scholarly journals Nonlinear Dynamic Analysis and Chaos Prediction of Grinding Motorized Spindle System

2019 ◽  
Vol 2019 ◽  
pp. 1-10
Author(s):  
Weitao Jia ◽  
Feng Gao ◽  
Yan Li ◽  
Wenwu Wu ◽  
Zhongwei Li
Keyword(s):  
Nonlinear Dynamic ◽  
High Speed ◽  
Chaotic Behavior ◽  
Nonlinear Dynamic Analysis ◽  
Phase Portraits ◽  
Impact Factors ◽  
Nonlinear Dynamic Model ◽  
Motorized Spindle ◽  
Spindle System ◽  
The Impact

The paper determines the impact factors of dynamics of a motorized spindle rotor system due to high speed: centrifugal force and bearing stiffness softening. A nonlinear dynamic model of the grinding motorized spindle system considering the above impact factors is constructed. Through system simulation including phase portraits and Poincaré map, the periodic behavior and chaotic behavior of the nonlinear grinding motorized spindle system are revealed. The threshold curve of chaos motion is obtained through the Melnikov method. The conclusion can provide a theoretical basis for researching deeply the dynamic behaviors of the grinding motorized spindle system.

Compressibility Effects in High Speed Air Flow

1931 ◽  
Vol 35 (247) ◽  
pp. 665-674
Author(s):  
S. G. Hooker
Keyword(s):  
Angular Velocity ◽  
Perfect Fluid ◽  
Mathematical Analysis ◽  
High Speed ◽  
Equations Of Motion ◽  
Centre Of Gravity ◽  
High Speeds ◽  
Real Fluid ◽  
Special Cases ◽  
Compressibility Effects

Any theoretical attempt to evaluate the forces and couples experienced by an aircraft when in flight by a mathematical analysis of the pressures exerted by the air when in motion about the various parts, leads to what have, so far, proved insuperable difficulties. It involves the integration of the equations of motion of a real fluid, and, except in a few very special cases, these have been insoluble. The actual motion of a fluid is affected by a number of its properties, and, in general, accounts would have to be taken of its density, viscosity, and at high speeds its compressibility. In certain circumstances the effect of these last two can be neglected and the classical theory of hydrodynamics dealing with the motion of a non-viscous, incompressible or perfect fluid can be applied. A further simplification consists in supposing that the motion is irrotational, that is, any small portion of the fluid at a point has no angular velocity about its centre of gravity.

Dynamic precision analysis and experimental verification of high-speed precision punch press

2016 ◽  
Vol 230 (20) ◽  
pp. 3655-3662 ◽  
Author(s):  
Fengfeng Hu ◽  
Yu Sun ◽  
Binbin Peng
Keyword(s):  
Elastic Wave ◽  
Dynamic Model ◽  
High Speed ◽  
Impact Factors ◽  
Superposition Method ◽  
Bottom Dead Center ◽  
Dynamic Precision ◽  
Modal Superposition Method ◽  
The Impact ◽  
Punch Press

In order to investigate the impact factors and their affection on high-speed precision multilink punch press (MPP), the dynamic model with different joint clearance was established, and the influence of different clearance and speed on the dynamic positional repeatability of bottom dead center (BDC) was analyzed. The elastic dynamic model of high-speed MPP was established, the affection of the elastic deformation and elastic wave on the positional repeatability of the BDC were presented by using modal superposition method to solve dynamic equation. Meanwhile, experiments on the dynamic repeatability of the BDC of the punch during working were completed. At last, the comparison of the experimental results with the analyzed results was given, and based on which, it can be concluded that the clearance, elastic wave and deformation are the key factors of the dynamic repeatability precision of the BDC.

scholarly journals Study on Elastic Dynamic Model for the Clamping Mechanism of High-Speed Precision Injection Molding Machine

2015 ◽  
Vol 2015 ◽  
pp. 1-13
Author(s):  
Xue-feng Chen ◽  
Jian-guo Hu ◽  
Yan-sheng Xu ◽  
Zhong-ming Xu ◽  
Hong-bo Wang
Keyword(s):  
Coordinate System ◽  
Dynamic Model ◽  
High Speed ◽  
Equations Of Motion ◽  
Elastic Vibration ◽  
Lagrange Equations ◽  
Beam Elements ◽  
Model Matrix ◽  
Absolute Coordinate System ◽  
Plastic Injection

This work centered on the double-toggle clamping mechanism with diagonal-five points for the high-speed precise plastic injection machine. Based on Lagrange equations, the differential equations of motion for the beam elements are established, in a rotating coordinate system and an absolute coordinate system, respectively. 43 generalized coordinates and a model matrix for the mechanism are created and some coordinate matrices are derived. By coupling the coordinate transformation and matrix manipulation, a high nonlinear and strong time-variant elastic dynamic model is obtained. Based on the dynamic model, a Kineto-Elasto Dynamics (KED) analysis and a Kineto-Elasto Static (KES) analysis are carried out, respectively. By comparing and analyzing the simulation results of KED and KES, the regularity of elastic vibration of the clamping mechanism in high-speed clamping process has been revealed.

The Recent Developments of Molecular Dynamics Simulation

2013 ◽  
Vol 444-445 ◽  
pp. 1370-1373
Author(s):  
Wen Hai Gai ◽  
Ran Guo ◽  
Yuan Yuan Liu
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Rapid Development ◽  
Equations Of Motion ◽  
Dynamics Simulation ◽  
Impact Factors ◽  
Lagrange Equations ◽  
Time Step ◽  
Basic Principles ◽  
Recent Developments

Based on the development of nanomaterials and the research on performance parameters of materials, molecular dynamics simulation has been rapid development and application. It is widely found that the material's physical, mechanical and other properties are both closely related to its macroscopic state and microstructure [. In order to explore and understand the nature of the material properties we need to analyze various impact factors including macroscopic, mesoscopic and microscopic. This paper describes the basic concepts and methods of molecular dynamics. The contents are comprised of time step, formulas such as Lagrange equations of motion and Hamiltonian equations of motion. The basic principles and recent developments of molecular dynamics were reviewed.

Analysis of the Non-Linear Dynamic Responses of an Elastic Rotor With a Slant Crack

2012 ◽  
Author(s):  
Xiangmin Zhang ◽  
Changping Chen ◽  
Liming Dai
Keyword(s):  
Equations Of Motion ◽  
Harmonic Balance Method ◽  
Rotor System ◽  
Dynamic Responses ◽  
Cracked Rotor ◽  
Lagrange Equations ◽  
Linear Dynamic ◽  
Slant Crack ◽  
Non Linear ◽  
Line Spring Model

Considering a rotor system with a slant crack, and using an equivalent line-spring model to simulate the slant crack of the rotor, the flexibility model of the slant-cracked rotor is derived. Then considered the geometric non-linearity and based on the Lagrange equations, the non-linear dimensionless differential equations of motion for the slant-cracked rotor are obtained. Further the non-linear dynamic responses of the single rotor system with a slant crack are discussed by the Galerkin method and the harmonic balance method. It’s detailedly studied that the angle, the depth and the position of the slant crack on the rotor all affect on the non-linear dynamic responses of the rotor system, and the conclusion is very significant to the design of the rotor system in the practical reference aspect.

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