• Proceedings of the KSR Conference
• /
• 2005.05a
• /
• pp.491-497
• /
• 2005

Brake system is indispensible functional part to the transportation machines such as railroad cars, and all of industrial machines. It is mechanical element to stop the movement or slow the speed, transforming kinetic energy of motion object into thermal energy through solid friction. According that recently the railroad cars have become high-speed, the technique in braking domain to secure the overall braking effort is making rapid progress. In particular, material development and manufacturing process are so important to secure friction performance, which is the core in braking performance of mechanical brake units. Wear of brake disk could mainly result in the diminishment of its life span due to thermal cracking, so the endurance against high temperature is required. On the other hand, in this case, the problem is that the side wear of pad, relative material is slightly increased because of enlargement of plastic deformation. It is necessary, therefore, to develop a disk material that will be used in the Tilting System mechanical brake units. The purpose of this paper is to make a study prior to developing brake disk of Tilting Train travelling at 200km/h and to propose the component of brake disk. Accordingly, I will conduct sufficient researches on technical documents of brake disk, that are basic documentations, analyze an impact on components, and further, considering braking degree of train, study for the basic proposal on brake disk's component of the train travelling at 200km/h, which has relatively minor influence of heat stress and maintains the friction. In this respect, I would like to investigate friction characteristics between disk and relative friction material via Test on some possible test segments, analyze and propose friction performance, temperature impact and so forth coming from the contact with pad, relative material to demonstrate the friction characteristics.

• Proceedings of the KSR Conference
• /
• 2011.05a
• /
• pp.283-288
• /
• 2011

The high heat resistant material for brake disc is required for higher speed trains. Although Aluminum is very expensive, it which has high thermal conductivity and low density has been adapted to high performance light-weight brake disc. In this study, we carry out the thermal stress analysis for suggested shape of Al hybrid brake disc which was designed to meet the optimal point between a performance and economic side. And we compare the results from the analysis to results of conventional disc at the same braking speed. The result show that the temperature on braking surface of Al hybrid disc is lower than the temperature on conventional disc surface, whereas the maximum thermal stress is larger than stress on conventional disc.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.18 no.5
• /
• pp.544-549
• /
• 2009

Thermal brake judder caused by the high friction heat of the brake disk. Hot thermal judder makes serious problems such as to be unstability to drivers or to decrease braking force of automobile. Because thermal judder vibration makes high vibration occurrence and thermal deformation of brake disk. Therefore it Is necessary to reduce or eleminate thermal Judder phenomenon by understanding and investigation. This paper introduces the thermal deformation arising from friction heat generation in braking and proposes the FEM analysis to predict the distribution of temperature and thermal deformation. the results of the FEM analysis show the deformed shape and temperature distribution of the disk brake. The optimization is performed to minimize the thermal judder of ventilated disc brake that is induced by the thermal deformation of the disk brake.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.21 no.4
• /
• pp.39-45
• /
• 2022

In this study, it was verified that carbon-ceramic brake discs can replace existing cast-iron brake discs of the same size. In addition, a method of pretreating carbon fiber to secure heat dissipation characteristics while using a small amount of carbon fiber was established. The thermal conductivity and bending strength characteristics were analyzed according to the carbon content, and brake braking tests were conducted. Through pretreatment, the maximum temperature was lowered by 16 ℃ compared to the case using only carbon fiber, and the cooling rate was improved by approximately 10% compared to metal brake discs. However, the total heat capacity increased as the mass increased owing to the reaction. Thus, the measured temperature was higher than that of the metal brake disc; therefore, additional research is required.

• Tribology and Lubricants
• /
• v.25 no.6
• /
• pp.421-426
• /
• 2009

The brake system is important part of automobile safety system. The disc brake system is divided two parts: the rotating axisymmetrical disc and the stationary pads. During braking, the kinetic energy and potential energy of moving vehicle were converted into the thermal energy through frictional heat between the brake disc and the pads. The frictional heat, which is generated on the interface of the disc and pads, can cause high temperature during the braking process. The object of present work is to determine temperature and thermal stress, to compare to simulation results and experimental results in the disc by partial 3D model of ventilated disc brake with appropriate boundary conditions. In the simulation process, the mechanical loads were applied to the thermo-mechanical coupling analysis in order to simulate the process of heat produced by friction.

• Proceedings of the KSR Conference
• /
• 2006.05b
• /
• pp.1151-1156
• /
• 2006

• Environmental Engineering Research
• /
• v.24 no.4
• /
• pp.680-689
• /
• 2019

Temperature effects on the generation of brake wear particles from railway vehicles were generated, with a particular focus on the generation of ultrafine particles. A real scale brake dynamometer test was repeated five times under low and high initial temperatures of brake discs, respectively, to obtain generalized results. Size distributions and temporal patterns of wear particles were analyzed through visualization using clustered heatmaps. Our results indicate that high initial temperature conditions promote the generation of ultrafine particles. While particle concentration peaked within the range of fine sized particles under both low and high initial temperature, an additional peak occurred within the range of ultrafine sized particles only under high initial temperature. The timing of peak occurrence also differed between low and high initial temperature conditions. Under low initial temperature fine sized particles were generated intensively at the latter end of braking, whereas under high initial temperature both fine and ultrafine particles were generated more dispersedly along the braking period. The clustered correlation heatmap divided particle sizes into two groups, within which generation timing and concentration of particles were similar. The cut-off point between the two groups was approximately 100 nm, confirming that the governing mechanisms for the generation of fine particles and ultrafine particles are different.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.6
• /
• pp.94-99
• /
• 2012

Due to economic growth, the number of cars has grown rapidly and consequently traffic accidents have grown in direct ratio. This reminds us that braking device of a vehicle is an important factor to prevent traffic accidents. Aim these researches to speed and lighten the braking system of vehicles, to lengthen its durability and to shorten the stopping distance. However, it is still difficult to analyze quantitatively and clearly the reason and solution for abnormal wear of disc and pad or judder in flywheel mode. Therefore this study was carried out to presume for mutual relation of analysis condition to get the optimum temperature by two-way layout. The results shown that coefficient of determination has a fine reliability over 92.57% and temperature is made by two-way layout.

• Journal of the Korean Society for Railway
• /
• v.10 no.6
• /
• pp.665-669
• /
• 2007

This study investigates the temperature change and thermal conductivity for the braking disc of the railway vehicle due to the types of train and service conditions. The temperature change was measured by non-contact Infrared thermometers. Average temperature was measured between $79.32^{\circ}C$ and $104.46^{\circ}C$ due to types of train and service section. In the same service section, the surface temperatures of Saemaul train were higher than Mugungwha train; the reason might have been the average service speed of Saemaul train (83km/h) was higher than Mugungwha train (107km/h), and the weight was similar 39t (Mugungwha) and 39.3t (Saemaul). But the maximum surface temperature was measured on the Mugungwha train; however the difference was not too big with the maximum temperature of Saemaul train. Also, the disc surface temperatures were changed due to the material of lining; metal and non-asbestos, on the same train and the same service section. In addition. the thermal conductivity was tested the thermal conductivities were increased by the increasing of the temperature. The change is too big between $100^{\circ}C$ and $200^{\circ}C$. But each average value is small. and the mechanical property change is very low. As a result, we conclude that this disc is suitable for usage between $100^{\circ}C$ and $300^{\circ}C$.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.11 no.4
• /
• pp.1178-1185
• /
• 2010

Recently, high speed of container freight cars is causing fatigue damage of wheel. Sudden failure accidents cause a lot of physical and human damages. Therefore, damage analysis for wheel prevents failure accident of container freight car. Wheel receives mechanical and thermal loads at the same time while rolling stocks are run. The mechanical loads applied to wheel are classified by the horizontal load from contact of wheel and rail in curve line section and by the vertical force from rolling stocks weight. Also, braking and deceleration of rolling stocks cause repeated thermal load by wheel tread braking. Specially, braking of rolling stocks is frictional braking method that brake shoe is contacted in wheel tread by high breaking pressure. Frictional heat energy occurs on the contact surface between wheel tread and brake shoe. This braking converts kinetic energy of rolling stocks into heat energy by friction. This raises temperature rapidly and generates thermal loads in wheel and brake shoe. There mechanical and thermal loads generate crack and residual stress in wheel. Wetenkamp estimated temperature distribution of brake shoe experimentally. Donzella proposed fatigue life using thermal stress and residual stress. However, the load applied to wheel in aforementioned most researches considered thermal load and mechanical vertical load. Exact horizontal load is not considered as the load applied to wheel. Therefore, above-mentioned loading methods could not be applied to estimate actual stress applied to wheel. Therefore, this study proposed safety estimation on wheel of freight car using heat-structural coupled analysis on the basis of loading condition and stress intensity factor.