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During the braking process, frictional heat generated between a disc and a pad can lead to high temperatures. The location of friction blocks on the brake pad can lead directly to differences in friction contact time and friction speed at each point on the brake disc surface, this can lead to non-uniform temperature distribution on the brake disc surface. In this paper, the optimum design for friction blocks on a brake pad is investigated using the design of experiments (DOE) of Taguchi approach and response surface method (RSM) with an aim to minimize the deviation in the rate of friction heating in each area along the radial direction of brake disc. 18 design variables on 2 levels are adjusted. A table of orthogonal arrays, L32 (218), is used. Finite element analysis (FEA) is performed to analyze the mean squared error (MSE) values in the temperature deviations from frictional heat, the disc's thermo-mechanical characteristics are taken into account. Analysis of variance (ANOVA) is carried out using the data gathered from the DOE stage, we find 7 significant factors among the design variables. A meta-model using RSM is proposed for reduction of temperature deviations over the brake disc. An optimized brake pad is analyzed in terms of the temperature and thermal stress imparted on the brake disc, this optimized pad is then compared with the original pad. The maximum temperatures of the optimized pad and original pad were 399.8 °C and 480.6 °C, respectively. The thermal stress of the optimized pad and original pad were 640.4 MPa and 721.4 MPa, respectively. In the optimized model, the size of the hot band on the disc is larger than that from the original model, so the thermal stress distribution on the disc is smaller. Finally, the optimized pad was found to give significant performance benefits with a 16.8 % decrease in maximum temperature and 11.2 % decrease in thermal stress. [ABSTRACT FROM AUTHOR]

The structure of a brake disc is coupled to the axle and rotates together with the wheel. A brake disc is a friction-type device that presses the pad on both sides of the disc. As more of its surface area becomes exposed to the air, it has better heat dissipation than the drum disc. It also has low fade phenomenon or vapor lock phenomenon despite frequent brake operation. In addition, it has the advantage of enabling precise control. But the braking force is obtained by the disc brake system by using the frictional force between the disc and the pad, and the pad is subjected to wear. For high-speed railway vehicles in particular, the wear and tear of the pad occurs more rapidly. This not only shortens the replacement cycle of the pad, but also has the disadvantage of reducing braking efficiency due to the rise in temperature during the initial braking process. Moreover, the heat that occurs will cause thermal distortion, which leads to the occurrence of a hot spot. This results in a reduction of the disc life. Looking comprehensively at the research trends to date it appears that thermal behavior analysis has only been performed thus far in terms of frictional thermal energy between the disc and the pad. Thermomechanical contact characteristics, on the other hand, have yet to be considered. The thermal behavior of the disc is analyzed experimentally using an infrared camera, and the causes of the hot band and hotspot are suggested. This analytical approach can shorten the analysis time, but it can only confirm the temperature distribution achieved by a single braking. While there is a significant difference in temperature distribution according to the actual braking, the analytical approach has solely focused on the hotspot generation mechanism. Therefore, in this study, the authors will use both a dynamometer and a thermographic camera to analyze BPs through a repetitive braking process, and will attempt to verify the cause of thermomechanical movement and BP occurrence through contact analysis of the disc and the pad. [ABSTRACT FROM AUTHOR]

One of the primary interests in the railway field is to improve speed as well as to secure the safety of railway vehicles at a high speed. In light of this, the demand for braking systems that offer improved performance and safety has also been growing consistently. The braking system is a critical element directly connected with safety. In order to secure reliability and establish the maintenance standard for the braking system, it is necessary to secure an accurate evaluation technology. As the braking disc of the braking system is very sensitive to safety and maintenance, a method to evaluate thermal cracking must be developed. Because the brake disc goes through a repeated process of heating and cooling due to the friction energy and the heat convection, respectively, in every braking action, it is subject to thermal fatigue. As well, the partial contact area caused by friction between disc and pad during the braking process results in thermal distortion, causing a hot band and a hot spot. This thermal distortion may also cause thermal cracking on the friction surface. The aim of this research was to find the cause of thermal cracking through a thermo-mechanical friction analysis of disc and pad, and to verify the analysis model through the dynamo machine. [ABSTRACT FROM AUTHOR]