Influence of the Primary Suspension Damping on the Ride Comfort in the Railway Vehicles

2019 ◽  
Vol 957 ◽  
pp. 53-62 ◽  
Author(s):  
Mădălina Dumitriu ◽  
Dragoş Ionuţ Stănică
Keyword(s):  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Numerical Study ◽  
Reference Value ◽  
Reference Points ◽  
Rail Vehicle ◽  
Power Spectral ◽  
Ride Index ◽  
Filtering Effect ◽  
Geometric Filtering

The paper features the results of a numerical study regarding the influence that the damping reduction in the primary suspension of the rail vehicle, due to the defect in a damper, has on the ride comfort. The study is based on model of rigid-flexible coupled vehicle, with seven degrees of freedom, where the carbody is modelled as an Euler-Bernoulli type equivalent beam. The results of the numerical simulations show the power spectral density of carbody vertical accceleration and the ride index comfort calculated in three carbody reference points - at the centre and against the bogies, for various cases of reduction in the damping constant of the primay suspension in the axle, compared to the reference value. As a function of velocity, due to the geometric filtering effect, the damping reduction has contrary effects upon the level of vibrations in the carbody and upon the ride comfort.

Analysis of generalized force and its influence on ride and stability of railway vehicle

2020 ◽  
Vol 51 (6) ◽  
pp. 95-109
Author(s):  
Rakesh Chandmal Sharma ◽  
Sakshi Sharma ◽  
Sunil Kumar Sharma ◽  
Neeraj Sharma
Keyword(s):  
Potential Energy ◽  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Contact Point ◽  
Railway Vehicle ◽  
Energy Potential ◽  
Dissipation Energy ◽  
Rail Vehicle ◽  
Random Track Irregularities ◽  
Lagrange’S Method

Formulation of a rail vehicle model using Lagrange’s method requires the system’s kinetic energy, potential energy, spring potential energy, Rayleigh’s dissipation energy and generalized forces to be determined. This article presents a detailed analysis of generalized forces developed at wheel–rail contact point for 27 degrees of freedom–coupled vertical–lateral model of a rail vehicle formulated using Lagrange’s method and subjected to random track irregularities. The vertical–lateral ride comfort of the vehicle and the ride index of the vehicle are evaluated based on ISO 2631-1 comfort specifications and stability is determined using eigenvalue analysis. The parameters that constitute the generalized forces and critically influence ride and stability have been identified and their influences on the same have been analysed in this work.

Control of Maglev Suspension Systems

1996 ◽  
Vol 2 (3) ◽  
pp. 349-368 ◽  
Author(s):  
Y. Cai ◽  
S.S. Chen
Keyword(s):  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Vehicle Suspension ◽  
Semiactive Control ◽  
One Dimensional ◽  
Suspension Systems ◽  
Maglev Vehicle ◽  
Power Spectral ◽  
Power Spectral Densities ◽  
Control Designs

This study investigates alternate designs for control of maglev vehicle suspension systems. Active and semiactive control-law designs are introduced into primary and secondary suspensions of maglev vehi cles. A one-dimensional vehicle with two degrees of freedom, simulating the German Transrapid Magiev System, is used. The transient and frequency responses of suspension systems and power spectral densities of vehicle accelerations are calculated to evaluate different control designs. The results show that both active and semiactive control designs improve vehicle response and provide acceptable ride comfort for maglev systems.

The Vibration Analysis of Five Degrees of Freedom Man-Vehicle-Road Coupled Model

2013 ◽  
Vol 765-767 ◽  
pp. 361-365
Author(s):  
Pei Cheng Shi ◽  
Wen Chen Xie
Keyword(s):  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Coupled Model ◽  
Reference Value ◽  
Response Characteristics ◽  
Vibration Model ◽  
Study Results ◽  
Road Surface Roughness ◽  
The Mathematical Model ◽  
The Relationship

The 5-DOF man-vehicle-road coupled vibration model is established by the relationship among three interactions of man-vehicle-road and the vibration differential equation of the 5-DOF man-vehicle-road model is obtained by Newtons method. The mathematical model is conversed into the derived simulation model based on MATLAB/SIMULINK software. The vibration characteristics of the 5-DOF couple model are analyzed by the excitations of ride speed and random road surface roughness time series since the corresponding parameters have been set. The paper demonstrates the acceleration curves and their response characteristics of the bodywork and man-chair system. The study results have a guiding significance and reference value to analyze the vehicle ride comfort.

Parametric Analysis of the Ride Comfort of Indian Railway Vehicle

2021 ◽  
Vol 13 (4) ◽  
Author(s):  
Rakesh Chandmal Sharma ◽  
Sono Bhardawaj ◽  
Mohd Avesh ◽  
Neeraj Sharma
Keyword(s):  
Mathematical Model ◽  
Parametric Analysis ◽  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Rear Wheel ◽  
Railway Vehicle ◽  
Mass System ◽  
Rail Vehicle ◽  
Indian Railway ◽  
The Mathematical Model

This paper focuses to the parametric analysis of Indian Railway Rajdhani (LHB) coach. A suitable mathematical model of 40 degrees of freedom (DOF) is formulated by Lagrangian method. The mathematical model of rail-vehicle is modelled by considering eleven mass system containing of backseat support (without cushion), a seat, a car body, two (front and Rear) bolsters, two (front and Rear) bogie frame and four wheelaxles (front bogie front and rear wheel axles and rear bogie front and rear wheel axles. The vehicle is simulated to travel at speed of 100 km/hr on a tangent track. The results from the simulation are validated by comparing the same with the results from experimental data which is acquired from research designs and standards organization (RDSO), Lucknow (India). The parametric analysis is performed to estimate the effect of different parameters of rail-vehicle on the ride behaviour.

scholarly journals Influence of Suspended Equipment on the Carbody Vertical Vibration Behaviour of High-Speed Railway Vehicles

2016 ◽  
Vol 63 (1) ◽  
pp. 145-162 ◽  
Author(s):  
Mădălina Dumitriu
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Coupled Model ◽  
Large Mass ◽  
Vertical Vibration ◽  
Reference Points ◽  
Railway Vehicles ◽  
Speed Regime ◽  
Vertical Vibrations

Abstract The equipment mounted on the carbody chassis of the railway vehicles is a critical component of the vehicle in terms of ride comfort. The reason for that is their large mass, able to visibly influence the vibrations mode of the carbody. The paper examines the influence of the equipment upon the mode of vertical vibrations of the carbody in the high-speed vehicles, reached on the basis of the frequency response functions of the acceleration in three carbody reference points - at the centre and above the bogies. These functions are derived from the numerical simulations developed on a rigid-flexible coupled model, with seven degrees of freedom. As a rule, the results herein prove the influence of the equipment mounting mode (rigid or elastic), along with the speed regime, upon the level of vibrations in the carbody reference points, at the resonance frequency of the symmetrical bending mode. Similarly, it is also demonstrated how the equipment mass and the damping degree of the suspension system affect the level of the vibrations in the carbody.

scholarly journals A numerical and scaled experimental study on ride comfort enhancement of a high-speed rail vehicle through optimizing traction rod stiffness

2020 ◽  
pp. 107754632096192
Author(s):  
Vahid Bokaeian ◽  
Mohammad Ali Rezvani ◽  
Robert Arcos
Keyword(s):  
Rigid Body ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Ride Comfort ◽  
Ride Quality ◽  
Railway Vehicle ◽  
Equivalent Linearization ◽  
Scaled Model ◽  
Rail Vehicle ◽  
Optimal Stiffness

In this research, the effect of rail vehicle carbody’s flexural modes on the ride comfort of an example high-speed railway vehicle is investigated. The vehicle is modeled as a rigid multi-body system, where the rigid body vertical, longitudinal, pitch, and roll degrees of freedom of the carbody and bogie frames and the rigid body vertical and roll degrees of freedom of the wheelsets are considered. An Euler–Bernoulli beam theory is used to account for the flexural motion of the carbody. The longitudinal interaction between carbody and bogie through the traction rod is modeled as a nonlinear spring element. The corresponding equations of motion of the system in the frequency domain are obtained by using the equivalent linearization method. The effect of the traction rod is explored by using this model. Also, the optimal stiffness of the traction rod element that minimizes the flexural vibrations of the carbody is obtained through a genetic algorithm. With the optimal stiffness for the traction rod, the ride quality index at the center of the carbody floor is improved by 41% at a speed of 300 km/h. For the validation of numerical results, a scaled model of the vehicle with a scale factor of 24.5 was constructed, and its associated results are presented. The model was excited by random input signals, which were generated based on the power spectral density of the track irregularity function. The agreement between the simulation results and the scaled experimental outcome when compared with the measured data from other sources is found to be satisfactory. In the framework of the physical scaled model, the filtering effect due to the vehicle bogie base is also examined.

Numerical study of the flow over the modified simple frigate shape

2020 ◽  
pp. 095441002097775
Author(s):  
Tong Li ◽  
Yibin Wang ◽  
Ning Zhao
Keyword(s):  
Bluff Body ◽  
Recirculation Zone ◽  
Numerical Study ◽  
Reference Value ◽  
Flow Fields ◽  
Navier Stokes ◽  
Detached Eddy Simulation ◽  
Eddy Simulation ◽  
Delayed Detached Eddy Simulation ◽  
Simulation Results

The simple frigate shape (SFS) as defined by The Technical Co-operative Program (TTCP), is a simplified model of the frigate, which helps to investigate the basic flow fields of a frigate. In this paper, the flow fields of the different modified SFS models, consisting of a bluff body superstructure and the deck, were numerically studied. A parametric study was conducted by varying both the superstructure length L and width B to investigate the recirculation zone behind the hangar. The size and the position of the recirculation zones were compared between different models. The numerical simulation results show that the size and the location of the recirculation zone are significantly affected by the superstructure length and width. The results obtained by Reynolds-averaged Navier-Stokes method were also compared well with both the time averaged Improved Delayed Detached-Eddy Simulation results and the experimental data. In addition, by varying the model size and inflow velocity, various flow fields were numerically studied, which indicated that the changing of Reynolds number has tiny effect on the variation of the dimensionless size of the recirculation zone. The results in this study have certain reference value for the design of the frigate superstructure.

scholarly journals Estimation of Wave Period from Pitch and Roll of a Lidar Buoy

Sensors ◽  
2021 ◽  
Vol 21 (4) ◽  
pp. 1310
Author(s):  
Andreu Salcedo-Bosch ◽  
Francesc Rocadenbosch ◽  
Miguel A. Gutiérrez-Antuñano ◽  
Jordi Tiana-Alsina
Keyword(s):  
Degrees Of Freedom ◽  
Translational Motion ◽  
Cutoff Frequency ◽  
Peak Level ◽  
Wave Period ◽  
Estimation Methods ◽  
Zero Crossing ◽  
Power Spectral ◽  
Period Estimation ◽  
Wind Lidar

This work proposes a new wave-period estimation (L-dB) method based on the power-spectral-density (PSD) estimation of pitch and roll motional time series of a Doppler wind lidar buoy under the assumption of small angles (±22 deg) and slow yaw drifts (1 min), and the neglection of translational motion. We revisit the buoy’s simplified two-degrees-of-freedom (2-DoF) motional model and formulate the PSD associated with the eigenaxis tilt of the lidar buoy, which was modelled as a complex-number random process. From this, we present the L-dB method, which estimates the wave period as the average wavelength associated to the cutoff frequency span at which the spectral components drop off L decibels from the peak level. In the framework of the IJmuiden campaign (North Sea, 29 March–17 June 2015), the L-dB method is compared in reference to most common oceanographic wave-period estimation methods by using a TriaxysTM buoy. Parametric analysis showed good agreement (correlation coefficient, ρ = 0.86, root-mean-square error (RMSE) = 0.46 s, and mean difference, MD = 0.02 s) between the proposed L-dB method and the oceanographic zero-crossing method when the threshold L was set at 8 dB.

Numerical study on the mechanism of drag reduction for interceptors on planning boats

2021 ◽  
Author(s):  
Lianzheng Cui ◽  
Zuogang Chen ◽  
Yukun Feng
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Numerical Study ◽  
Dynamic Pressure ◽  
Motion Model ◽  
Gauge Pressure ◽  
Reduction Effect ◽  
Pressure Resistance ◽  
Viscous Pressure

The drag reduction effect of interceptors on planning boats has been widely proven, but the mechanism of the effect has been rarely studied in terms of drag components, especially for spray resistance. The resistance was caused by the high gauge pressure under the boats transformed from the dynamic pressure, and it is the largest drag component in the high-speed planning mode. In this study, numerical simulations of viscous flow fields around a planning boat with and without interceptors were conducted. A two degrees of freedom motion model was employed to simulate the trim and sinkage. The numerical results were validated against the experimental data. The flow details with and without the interceptor were visualized and compared to reveal the underlying physics. A thinner and longer waterline could be achieved by the interceptor, which made the boat push the water away more gradually, and hence, the wave-making resistance could be decreased. The improved waterline also reduced the component of the freestream normal to the hull surface and led to the less transformed dynamic pressure, resulting in the lowAer spray resistance. Furthermore, the suppression of the flow separation could also be benefited from the interceptor; the viscous pressure resistance was therefore decreased.

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