RTRI was involved in approximately 280 research themes in the fiscal year 2017 to 2018. Among them, 46 were related to rolling stock technology, covering a wide range of themes, in practical, applied and fundamental research, such as: the increase in train running speed and improvement of ride comfort, the applied research such as the running stability and reliability of rolling stock, and elucidation of the mechanisms leading to wheel wear. Three topics from this research and described in this paper are: "Quantitative evaluation of wheel flats affecting vehicle bogie behavior," "Development of a 3-Dimentional measurement device for wheel profiles" and "Evaluation of the running safety of railway vehicles in case of air spring deflation."
The construction of many railway structures predates those for roads. Yet, up until today they have continued to enable safe and stable railway operations, thanks to good maintenance management. This means that even on major lines, some structures have an age exceeding 70 years. While there is high demand for railway structure repair and reinforcement technology, restoration technologies including for functional improvements are also needed. This paper therefore gives an overview of the current state of railway bridges and viaducts and introduces recent research and development trends in restoration technology for bridges and viaducts developed by the Railway Technical Research Institute.
RTRI is advancing its fundamental research on superconducting maglev. The areas being investigated include experimental evaluation of REBCO high-temperature superconducting coils, numerical analysis of the effect of magnetic springs on maglev vehicles, development of a system for collecting data from sensors in ground coils, inter alia. RTRI is also promoting research on the application of maglev technology to the conventional railway system, where research is focused on contactless power supply systems and flywheel energy storage systems.
In order to decrease the lateral force generated in railway vehicles in curved sections, a simple steering system for bolsterless bogies has been developed. This bogie steering system does not adopt a complex bogie structure, and is equipped with a function to prevent reverse steering. The system is referred to as an "Assist steering system," It is composed of pneumatic actuators built into mono-links, a mechanical sensor to detect the bogie angle from the relative movement between the bogie and the car body, and a pneumatic valve that works according to the sensing device.
In the RTRI detailed equation, which is a method of static analysis of railway vehicles overturning under crosswind, static force is substituted for the vibrational inertial force of the car-body. However, since the lateral vibration of the car-body is a dynamic phenomenon, the influence of the lateral vibration on overturning conceivably depends on the amplitude and frequency of the vibration. Thus, we examined the relation between the lateral vibration and the wheel load variation by numerical simulation. We also verified the validity of the simulation results by comparing them with the data acquired through on-track running tests.
The disc brake is mounted on the high speed vehicle from a thermal problem point of view. By the influence of the frictional heat generated remarkably by a higher speed, the braking performance of the disc and the pad is reduced in some cases. Therefore, past researches have been conducted mainly with a focus on the friction surface observed by the high-speed thermo-camera. Then, we have established a method of measuring the disc deformation during braking. In this paper, we report on the results of the investigation of the relationship between the deformation and the friction phenomenon executed by dynamo bench tests.
When ground liquefaction occurs, settlement is often caused by shear deformation during and consolidation after an earthquake. However, settlement does not occur regularly but usually varies in space. In order to clarify the mechanisms underlying non-uniform settlement caused by liquefaction, 2-dimensional effective stress analyses were performed on a field damaged in the 2011 off-the-Pacific-coast-of-Tohoku earthquake. Distributions of the thickness and resistance of the liquefiable layer obtained from field surveys were considered in the numerical models. Simulated results confirmed that the non-uniform settlement was caused by the spatial distribution of the thickness and resistance of the liquefiable layer.
This paper presents conclusions drawn from model tests of mountain tunnel linings consisting of various materials. Plain concrete linings did not show any decrease in load, indicating good deformability, whereas compressive cracks and spalling occurred. Brick linings demonstrated lower structural stiffness and bearing capacity than plain concrete linings, and interlayer cracks occurred. Short-fiber-reinforced concrete linings showed good anti-spalling performance, whereas structural stiffness and bearing capacity were almost the same as in plain concrete linings. Reinforced concrete linings had the highest structural stiffness and bearing capacity, but displayed frequent shear failures.
The type of structural supports used for ceilings in stations differ from those used in other buildings. In order to evaluate the seismic performance of station ceilings, it is therefore necessary to understand the function of supporting parts in the structure, and to evaluate loads acting on the ceiling during earthquakes. Shaking table tests and analytical studies of existing suspended station ceilings were conducted, focusing on the function of supporting parts in the structure. Seismic design to be applied to the method of improving the ceiling of the existing stations so as to make it safer during earthquakes is proposed.
A superconducting magnetic bearing (SMB) has been developed with high temperature superconducting (HTS) coils and bulks for a flywheel energy storage system (FESS). The FESS equipped with the SMB was tested at the mega photovoltaic power plant test site in Yamanashi Prefecture. The SMB with both rotor and stator made of superconducting material, was capable of supporting the flywheel weighing 4000 kg without any contact and has so far remained in stable operation for 5000 hours. A further increase in storage capacity is required for the FESS to be applicable to railways as a system for preventing cancellation of regenerative braking. This paper describes the development of a SMB capable of supporting large 147 kN loads using a new type coil structure for the improvement of FESS storage capacity.
Development of REBCO (Rare-Earth Barium Copper Oxide) magnets has been ongoing with the purpose of reducing the cost of operating maglev trains. On-board superconducting magnets are exposed to severe vibrations due to the varying magnetic field. This paper describes mechanical vibration tests on an actual REBCO coil. The coil was vibrated at 10 G (98 m/s2) by excitation. The heat load due to vibrations was less than 2 W, which is a small percent of the total heat load. In addition, eddy current heating was evaluated with numerical electromagnetic analysis.
The lateral and rolling components of the magnetic springs of superconducting Maglev vehicles are strongly coupled, and their characteristics are barometers to decide the take-off velocity of the vehicle. In order to design Maglev vehicles effectively, it is important to understand the principles to be applied to determine the spring specifications with respect to the design parameters: the gap and the magnetomotive force of the superconducting magnet. In this paper, a study using computer simulations on the effect of changing the design parameters is described, referring to the principles of electrodynamic suspension and the vehicle dynamics of Maglev vehicles.