Yoshiaki Terumichi

Experimental study on mechanism of rail corrugation using corrugation simulator

This paper presents experimental study on corrugation phenomenon growing on the top surface of rail in a tight curve of track. One of the characteristics of the corrugation is to involve a slight slip, i.e. creepage, in rolling contact surfaces between rails and wheels. In order to examine the mechanism of corrugation, the authors reproduced the phenomenon in experiments. In particular they examined it with focusing on the value of steady creepage. From this investigation, the effect of steady creepage on corrugation development has been cleared.

Dynamics of track/wheel systems on high-speed vehicles

For high speed railway vehicles, we consider a vibiation of flexible track/wheel system It is very important to deal with the complex phenomena of high-speed vehicles that can be occurred in the vertical vibration of the system From a viewpoint of multibody dynamics, this kind of problem needs accurate analysis because the system includes mutual dynamic behaviors of rigid body and flexible body The simulation technique for the complex problems is also discussed We consider the high-speed translation, rail elasticity, elastic supports under the rail and contact rigidity Eigen value analysis is also completed to verify the mechanism of the coupled vertical vibration of the system

Behavior of Three Kinds of Particles in Rotary Barrel with Planetary Rotation

Barrel polishing is an extremely efficient processing method for the surface smoothing treatment of a large number of workpieces. However, workpieces and grinding materials may separate depending on processing conditions. Since barrel polishing is carried out while mixing workpieces and grinding materials, the occurrence of segregation should be avoided. The processing conditions inside a planetary barrel which simultaneously rotates around the horizontal axis and revolves around the vertical axis include many unknown factors as well as the occurrence of segregation. The motions of workpieces and grinding materials in this barrel are basically the same as those of particles undergoing planetary rotation in a cylindrical barrel. However, in order to calculate the behavior of a large number of particles, a numerical method that can be applied to a discrete body is necessary. Therefore, in this study, two kinds of particles of different materials and sizes were filled into a planetary barrel, and the behavior of those particles was examined through experiments and simulations using the Discrete Element Method (DEM). As a result, it was demonstrated that certain combinations of length and inside diameter of the rotary barrel could prevent the segregation.

The dynamic behaviour of a non-stationary elevator compensating rope system under harmonic and stochastic excitations

Moving slender elastic elements such as ropes, cables and belts are pivotal components of vertical transportation systems such as traction elevators. Their lengths vary within the host building structure during the elevator operation which results in the change of the mass and stiffness characteristics of the system. The structure of modern high-rise buildings is flexible and when subjected to loads due to strong winds and earthquakes it vibrates at low frequencies. The inertial load induced by the building motion excites the flexible components of the elevator system. The compensating ropes due to their lower tension are particularly affected and undergo large dynamic deformations. The paper focuses on the presentation of the non-stationary model of a building-compensating rope system and on the analysis to predict its dynamic response. The excitation mechanism is represented by a harmonic process and the results of computer simulations to predict transient resonance response are presented. The analysis of the simulation results leads to recommendations concerning the selection of the weight of the compensation assembly to minimize the effects of an adverse dynamic response of the system. The scenario when the excitation is represented as a narrow-band stochastic process with the state vector governed by stochastic equations is then discussed and the stochastic differential equations governing the second-order statistical moments of the state vector are developed.

Modelling, Simulation and Analysis Techniques in the Prediction of Non-Stationary Vibration Response of Hoist Ropes in Lift Systems

The paper presents the results of a study in which the non-stationary dynamic response of typical lift installations is investigated. A general approach to describe the dynamic behaviour of a vertical transport installation is presented. Subsequently, vibration models of a building elevator and a mine hoist installation are discussed. Perturbation and numerical techniques are discussed and applied to predict the non-stationary response of hoist ropes. It is shown that the method of multiple scales with non-linear scale as well as the method of characteristics can be employed to analyse a passage through resonance in a simple lift installation. Furthermore, the effectiveness of direct numerical integration of equations of motion is demonstrated in the case of a mine hoist installation.

Numerical and Experimental Approaches on the Motion of a Tethered System With Large Deformation, Rotation and Translation

In this paper, we discuss the motion of a tethered system. In general, a tether is a cable or wire rope, and a tethered system consists of a tether and attached equipment. A tethered subsatellite in space is an example of this system. We consider the tethered system consisting of a very flexible body (the tether) and rigid bodies at one end as our analytical model. A flexible body in planer motion is described using the Absolute Nodal Coordinate Formulation. Using this method, the motion of a flexible body with large deformation, rotation and translation can be expressed with the accuracy of rigid body motion. The combination of flexible body motion and rigid body motion is performed and the interaction between them is discussed. We also performed experiments to investigate the fundamental motion of the tethered system and to evaluate the validity of the numerical formulation. The first experiments were conducted using a steel tether and rubber tether in gravity space. We also conducted experiment of the motion of the tethered system with a rigid body in microgravity space. The numerical solutions using the proposed methods for the modeling and formulation for the tethered system are in good agreement with the experimental results.Copyright

Numerical and Experimental Study on Contact Force Fluctuation Between Wheel and Rail Considering Rail Flexibility and Track Conditions

In the present study, we propose an analytical model with a multibody system considering three-dimensional wheel/rail contact geometry and ballasted track characteristics. Suppression of contact force fluctuation between the wheel and rail is desirable from the viewpoint of ensuring running safety, track maintenance, ride comfort, and minimizing the impact of factors such as noise on the surrounding environment. In the present paper, we investigate the effects of the support characteristics of ballasted track on the interaction between vehicles and tracks. Numerical simulations and experiments are carried out for railway vehicle motion under a wide range of ballasted track rigidities. Using the proposed numerical model, we obtain analysis results that are consistent with experimental results under two different track conditions: one simulating ordinary ballasted track characteristics and one that provides sufficient space between sleepers and ballasts. The proposed numerical simulation can accurately analyze vehicle motion running over ballasted track by considering the interaction between the vehicle and the track.

Development of Tether Space Mobility Device

With the increasing use of the International Space Station, humans have more opportunities to work in space. In space, a mobility device that operates efficiently is needed. In this research, a mobility system called the “Tether Space Mobility Device” (hereinafter called TSMD) is proposed. In general, the tether is a cable or a wire rope. The proposed system has a mechanism that uses the tether for enabling a human to move to a target point. However, this system has the problem that the center of mass of the human and that of the TSMD are different from the direct line to the target point. Then, the human is rotated by the tension of the tether. Thus, to use this device safely, rotation of the human body must be controlled. For this reason, a numerical simulation model is proposed. The numerical model is composed of three rigid bodies and one flexible body that can express motion with large deformation and large displacement. In this model, winding motion of the tether can be expressed. An experiment of the TSMD was designed to move under two-dimensional microgravity. The experiment confirmed the validity of the numerical simulation model. The possibility of the mobility device using the tether and the influence of the control system are discussed.

Development of a test stand for Maglev vehicles using hardware-in-the-loop simulation

A test stand consisting of one-third segment car body which simulates bending vibration is developed to evaluate ride comfort of maglev vehicles. The test stand utilizes hardware-in-the-loop simulation (HILS), which simulates motion of the missing segment using numerical simulation. Experimental results confirm that the test stand with the HILS system can generate the bending vibration accurately. Then, a method to reduce the bending vibration is proposed. Fundamental experiments using the test stand indicate that the optimally-designed anchor, a coupling element between the car body and the bogie, can reduce the bending vibration. It is expected that this test stand will lead to improvement of ride comfort of maglev vehicles.

Analysis on Wheel Load Variation in Coupled Motion Between Running Wheel and Track with Irregularity

The decrease of wheel load variation is effective in enhancing stability, safety of high-speed train. In this paper, we conduct the simulation analysis on wheel load variation in order to figure out the mechanism of wheel load variation in consideration of track irregularity such as sine wave and to investigate the influence of the relation between unsprung mass and static wheel load. As a result, we figured out as follows : The wheel load variation at high speed increases according as the wheel speed because the vertical inertia force of wheel increases widely by high-speed running along the flexible rail with irregularity. If sleeper passing frequency and the irregularity passing frequency is close to the primary natural frequency of the wheel/rail system, the wheel load variation becomes larger. The decrease of wheel mass is very effective in decreasing the wheel load variation in comparison with the decrease of static wheel load.