Abstract
Temperature evolution of the train brake disc during high-speed braking was investigated using in situ experiments, theoretical analysis, and finite element modeling. The experimental results show that the temperature distribution on the friction surface experienced the formation of a hot ring first, then expansion and duration of the hot ring. Alternative hot spot and cold zone were observed on the friction surface, which is attributed to the local contact in the friction couple and heterogeneous heat dissipation condition in the disc. The corresponding maximum temperature in the disc increased rapidly first, kept stable then, and decrease slowly in the end. The one-dimensional heat conduction equation was applied to predict the maximum temperature variation and was found to be in agreement with the experimental results. Furthermore, the maximum temperature evolution and the temperature distribution of the disc at the braking time of 45 s were simulated by the finite element method, which is satisfactory. In additional, the temperature variation caused the corresponding fluctuation of instantaneous frictional coefficient and thermal stress distribution in the disc, which results in the thermal damages.
Highlights
Increasing maximum running speed and weight reduction represent key development challenges in modern railway systems.[1,2] The increase of speeds while improving operating efficiency must ensure the safe operating conditions
Temperature evolution of the brake disc during high-speed braking was investigated using in situ experiments, theoretical analysis, and finite element (FE) method
The following conclusions can be drawn: 1. Temperature evolution of the disc by in situ measurement indicates that a hot ring forms and expanses to the whole friction surface, and the hot ring consists of alternative hot spot and cold zone hot spots and cold zones
Summary
Increasing maximum running speed and weight reduction represent key development challenges in modern railway systems.[1,2] The increase of speeds while improving operating efficiency must ensure the safe operating conditions. The integrity of the brake system is the guarantee of priority in the process of train speed design.[3,4] A key concern is that during a braking, the friction between the disc and pads generates a significant amount of heat. The accumulation and dissipation of heat are instantaneous and result in a rapid increase and decrease of temperature in the brake disc.[5,6] The hot spots and thermal fatigue caused by rapid increase and decrease of temperature are the main failure cause of the disc.[7,8] achieving a better understanding of temperature evolution is an important topic in the design and application of brake disc
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