2026-10-11T00:10:46Z https://www.scidb.cn/oai

10.57760/sciencedb.Tribology.00066 2026-06-22T15:38:58Z

2026-06-22 Influence of Composite Brake Pad Materials on Stick-Slip Vibration Behavior in Train Braking doi:10.57760/sciencedb.tribology.00066 en Stick–slip vibration during braking can significantly compromise the stability of braking performance and poses potential risks to the operational safety of urban rail vehicles. To elucidate the influence of composite brake pad materials and their mechanical characteristics on braking stick–slip vibration, this study investigated three typical in-service composite brake pads with distinct elemental compositions and compressive moduli through systematic tribological experiments, in which pronounced stick–slip behavior was observed under varying braking pressures. A multi-scale analysis framework was employed to reveal the underlying mechanisms, where the macroscopic vibration response was monitored in real time, the evolution of the friction interface was quantitatively characterized via white light interferometry and scanning electron microscopy to analyze contact plateau distribution, wear morphology, and surface roughness, and the tribochemical processes governing friction film formation were examined by energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy. In addition, finite element simulation was conducted to analyze the evolution of contact stress and effective contact area during the stick–slip process. The results demonstrated that stick–slip vibration was jointly governed by the elemental composition and compressive modulus of the brake pads through a coupled mechanical–chemical mechanism. The brake pad with a high compressive modulus and iron-rich composition exhibited the most severe stick–slip vibration and the largest difference between static and dynamic friction coefficients. Mechanically, the high compressive modulus restricted local deformation of the friction material, leading to pronounced stress concentration and a discontinuous, unstable contact state, which was consistent with simulation results showing elevated contact pressure peaks and reduced effective contact area. Chemically, the iron-dominated system tended to generate loose iron oxide particles with poor structural integrity, disrupting the continuity of the friction film and accelerating surface roughening. In contrast, the brake pad characterized by a lower compressive modulus and a calcium-rich composition showed the most stable friction behavior with minimal vibration, as the lower modulus improved interfacial conformability, enabling a more uniform stress distribution and a larger, more stable effective contact area. Concurrently, the high calcium content induced a competitive oxidation mechanism whereby preferential oxidation of calcium suppresses the formation of non-protective iron oxides and promotes the development of a dense, smooth, and mechanically stable tribofilm. This stable interface reduced friction coefficient fluctuations and effectively suppressed the onset of stick–slip instability, providing experimental evidence and mechanistic insight for optimizing composite brake pad materials—by combining a relatively low compressive modulus with a calcium-dominated oxidation mechanism—to mitigate stick–slip vibration in urban rail braking systems. train braking; stick-slip vibration; compressive modulus; friction and wear; material elemental composition Niu Rui Patriotic Era Fan Zhiyong Cao Yunli Xiong Kun Wang Zhiwei Mo Jiliang PUBLIC https://creativecommons.org/licenses/by-nc-nd/4.0/ dataset Science Data Bank