Investigation on the Bogie Hunting Motion of a Scale Model Railway Vehicle Running on a Double-Curved Rail

2016 ◽  
Vol 2016 (0) ◽  
pp. J1810104
Author(s):  
Barenten SUCIU ◽  
Ryoichi KINOSHITA
Keyword(s):  
Scale Model ◽  
Railway Vehicle ◽  
Hunting Motion

Effect of wind gusts on the dynamics of railway vehicles running on a curved track

2017 ◽  
Vol 232 (4) ◽  
pp. 1103-1120 ◽  
Author(s):  
Wonhee You ◽  
Hyukbin Kwon ◽  
Joonhyuk Park ◽  
Yujeong Shin
Keyword(s):  
Dynamic Characteristics ◽  
Wind Tunnel Test ◽  
Simulation Software ◽  
Scale Model ◽  
Railway Vehicle ◽  
Wind Gust ◽  
Railway Vehicles ◽  
Wind Gusts ◽  
Pitch Moment ◽  
Curved Track

Due to global warming, there is an increasing number of wind gusts that affect the stability of railway vehicles. A railway vehicle running on a curved track during a wind gust is subjected to multiple forces simultaneously, which include the centrifugal force and forces exerted by the wind gust and cant, and they significantly affect the vehicle’s dynamic characteristics as well as its safety. The forces increase the vibration of carbodies and the risk of derailment and overturning of cars; the effect is worse on irregular tracks. In order to review the phenomenon in detail, a 1/20 scale model of a railway vehicle was built to measure the aerodynamic coefficients in five directions—side force, lift force, roll moment, pitch moment, and yaw moment—through a wind tunnel test. The data collected were applied as external forces to a full-scale railway vehicle model traveling on a curved track. Using a multibody simulation software program, SIMPACK, a railway vehicle was modeled, which was then used in the simulation of the dynamic characteristics and safety of vehicles while traveling on a curved track during a wind gust. Using the actual measured track data from the curved zone, a comparison was made on the dynamic characteristics of the car traveling, with and without a wind gust, on a curved track with a railway curve radius of 599 m; also, the difference was analyzed with the direction of the wind gust blowing from inside and toward the center of curvature. The results showed that in the presence of a wind gust blowing from outside the curvature with an average speed of 25 m/s it is advisable to stop train services on grounds of safety.

scholarly journals Computation of the Negative Damping Associated to the Hunting Motion of the Railway Wheelset, without Using Geometrical or Tribological Restrictions into the Model

2020 ◽  
Vol 5 (2) ◽  
pp. 210-217
Author(s):  
Barenten Suciu
Keyword(s):  
Characteristic Equation ◽  
Opposite Sign ◽  
Damping Ratio ◽  
Complex Conjugate ◽  
Railway Vehicle ◽  
Real Roots ◽  
Vibration Model ◽  
Hunting Motion ◽  
Negative Damping ◽  
Analytical Expressions

Recently, analytical expressions for the damped natural frequency and damping ratio were proposed for the so-called dynamical hunting, either by assuming that the wheel conicity can be neglected, or by imposing restrictions on the ratio between the lateral and longitudinal creep coefficients, and also, on the ratio of the track span to the yawing diameter. However, instead of a pair of complex conjugate roots, and two real roots, of opposite sign, two pairs of complex conjugate roots were obtained for the characteristic equation. Purpose of this work is to achieve accurate expressions for the damping associated to the hunting motion, without imposing geometrical or tribological limitations into the vibration model, and to evaluate the error on the damping ratio, introduced by the simplified models. Also, nature of the roots of the characteristic equation is discussed, relative to the critical speed of the railway vehicle.

scholarly journals Multimodal Reduction of Elastic Vibrations in Plate Structure using Super Absorbent Polymer Beads

2020 ◽  
Vol 3 (1) ◽  
pp. 21-29
Author(s):  
Takahiro Tomioka ◽  
Karen Minamisawa
Keyword(s):  
Vibration Reduction ◽  
Basic Mechanism ◽  
Vibration Measurement ◽  
Scale Model ◽  
Railway Vehicle ◽  
Polymer Beads ◽  
Super Absorbent Polymer ◽  
Elastic Vibrations ◽  
Reduction Effect ◽  
Absorbent Polymer

This paper deals with multimodal reduction of structural elastic vibrations. Super absorbent polymer beads (SAP beads) have been introduced as a simple damping device inspired by the multimodal vibration reduction effect by passengers on railway vehicles. A series of vibration measurement tests using a 1:10 scale model of railway vehicle floor structure (model underframe) was carried out. The SAP beads which are sold commonly as water retention agent were stacked in a container and applied to the model underframe. From the experiments, multimodal vibration reduction effects have been demonstrated. A drastic difference has been observed when water was added together with SAP beads. To investigate the basic mechanism of the damping effect obtained by the experiments, an analytical model, which consists of multiple masses that are supported at an angle to each other, and its simplified model was proposed and numerical studies were conducted. Some specific combinations of the mass, spring, and damping elements in the model could express the experimental results well, and it has been estimated from the numerical results that each SAP layer act as an un-uniform subsystem.

The Hunting Behavior of Conventional Railway Trucks

1972 ◽  
Vol 94 (2) ◽  
pp. 752-761 ◽  
Author(s):  
N. K. Cooperrider
Keyword(s):  
Equations Of Motion ◽  
Linear Equations ◽  
Nonlinear Effects ◽  
Complex Model ◽  
Railway Vehicle ◽  
Hunting Behavior ◽  
Wheel Slip ◽  
Wheel Load ◽  
Hunting Motion ◽  
Nonlinear Equations Of Motion

Railway vehicles under certain conditions experience sustained lateral oscillations during which the wheel flanges bang from one rail to the other. It has been found that this behavior, called hunting, only occurs above certain critical forward velocities. Approximations to these critical velocities have been found from a stability analysis of the linear equations of motion for many different railway vehicle models. Hunting is characterized by violent motions that impose large loads on the vehicle and track, and bring several important nonlinear effects into play. This paper reports results of an analysis of nonlinear equations of motion written for two models of a railway truck. The influence of the nonlinear effects on stability is determined and the character of the hunting motion is investigated. One model represents a truck whose axle bearings are rigidly held in the truck frame while the truck frame is connected through a suspension system to a reference that moves along the track with constant velocity. The more complex model includes additional suspension elements between the axle bearings and truck frame. The effects of flange contact, wheel slip and Coulomb friction are described by nonlinear expressions. These results show the significant influence of flange contact on stability, and illustrate the effects of vehicle and track parameters such as rail adhesion, forward velocity, and wheel load on the forces and power dissipation at the wheel-rail interface.

Problems on Hunting of Railway Vehicle on Test Stand

1969 ◽  
Vol 91 (3) ◽  
pp. 879-885 ◽  
Author(s):  
T. Matsudaira ◽  
N. Matsui ◽  
S. Arai ◽  
K. Yokose
Keyword(s):  
Experimental Study ◽  
Field Test ◽  
Model Test ◽  
Effective Means ◽  
Scale Model ◽  
Railway Vehicle ◽  
Stand Test ◽  
Dummy Load ◽  
Roller Rig ◽  
Vehicle Test

The stand test in which a vehicle is set on a roller rig to simulate its running state is available as one of the effective means for experimental study on the hunting of vehicle. Here several questions arise: Whether or not a scale model test can substitute for an actual vehicle test; whether or not a bogie with a dummy load can represent a whole car in a stand test; and whether or not a stand test produces a similar result to a field test. The present paper summarizes the results of the studies about these questions conducted at the Railway Technical Research Institute of the Japanese National Railways.

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