Railway Engineering Science (铁道工程科学)•2026•DOI: 10.1007/s40534-025-00379-3
Stick–slip vibration in disc brake systems at low speeds arises from the interaction of multiple factors, posing persistent challenges for high-speed train safety and passenger comfort. This study establishes three- and four-degree-of-freedom (DOF) dynamic models that incorporate wheel–rail adhesion and nonlinear friction, validated through line testing. System stability, stick–slip bifurcation characteristics, and key influencing factors are analyzed via numerical simulation. Results demonstrate that the four-DOF model, by accounting for normal motion, avoids the over-evaluation of system stability inherent in the three-DOF model. In the three-DOF model, tangential stiffness is the primary factor inducing chaotic stick–slip vibration. In the four-DOF model, tangential stiffness predominantly affects vibration amplitude, while normal stiffness governs the onset of chaos. Damping exhibits minimal influence on chaotic stick–slip occurrence. Optimal parameter ranges are identified: brake disc rotational inertia of 5–9 kg·m² and 11–22 kg·m², and friction pad mass of 7–17 kg, which effectively mitigate chaotic stick–slip vibration. These findings provide quantitative guidelines for brake system design, enhancing operational reliability and reducing wear-related failures in high-speed rail applications.
Nano Research•2026•DOI: 10.26599/FRICT.2026.9441216
The vibration and noise issues of lightweight friction pairs in suburban train braking systems have become a critical bottleneck restricting their engineering application. This study investigated lightweight friction pairs composed of three representative synthetic brake pads and an aluminum matrix composite brake disc. Utilizing tribological tests, interfacial wear analysis, and dynamic modeling, the study investigated the impact of interfacial wear and contact behaviors on vibration and noise and elucidated the mechanisms by which pad material properties influence these responses. The experimental findings revealed that the pad material properties significantly affect the wear behavior and friction-induced vibration and noise responses of lightweight friction pairs. The pad enriched with lubricating phases (Pad A) readily established stable lubricating films, while the highly plastic pad (Pad C) effectively captured wear debris to build the third-body layers that cushioned loads. Both reduced friction fluctuations and contact stiffness, thereby attenuating vibration and noise. Conversely, the high-hardness pad (Pad B) failed to form continuous lubricating films, leading to intensified friction, higher contact stiffness, and pronounced vibration and noise. Numerical simulations further confirmed that the friction coefficient and normal contact stiffness synergistically regulated system stability, directly affecting the vibration and noise responses. Systems characterized by high friction and large contact stiffness (Pad B) were particularly susceptible to modal coupling, resulting in dynamic instability and elevated vibration and noise levels. Therefore, optimizing the pad material properties and regulating the behavior of wear debris to facilitate the stable formation of lubricating films or third-body layers can effectively suppress friction coefficient fluctuations, reduce normal contact stiffness, and enhance interfacial stability, thereby mitigating vibration and noise. The findings provide a theoretical foundation and engineering guidance for optimizing the design of low-noise lightweight braking systems and selecting appropriate friction materials.
Chinese Journal of Energetic Materials (含能材料)•2026•DOI: 10.11943/CJEM2026001
To improve rock fragmentation in open-pit deep-hole blasting, an in-hole layered column charge configuration was designed. Small-scale blasting tests on sandstone specimens were conducted under continuous and layered column charges to capture the failure process and final fragmentation. DEM-PBM coupled simulations visualized the dynamic fracture evolution and validated the experimental observations. Results show that under continuous charge, the top quarter of the specimen developed only a single blast-induced crack, splitting it into two parts, with horizontal fragment velocity of 2.0 m·s⁻¹ and a maximum block size of 9.0 cm. In contrast, layered charge produced multiple cracks in the top quarter, fragmenting it into smaller pieces, increasing horizontal velocity to 7.0 m·s⁻¹, and eliminating blocks larger than 5.0 cm. Simulations confirmed these trends, with maximum block size reduced from 8.8 cm to below 5.0 cm and velocity reaching 6.8 m·s⁻¹, closely matching experiments. Field trials in an open-pit coal mine overburden blasting demonstrated that layered charge reduced the boulder yield from 48.1% to 5.6%, significantly improving fragmentation. The findings confirm the practical effectiveness of in-hole layered column charge in enhancing rock breakage in deep-hole bench blasting.
Journal of Central South University•2026•DOI: 10.1007/s11771-026-6267-5
Previous earthquakes indicate that near-source canyon topographic effect (NCTE) can substantially amplify the seismic responses of canyon-crossing bridges (CCBs). While the conventional practices are to make disaster response decisions based on the deterministic approaches, they cannot provide a holistic view regarding the impacts of uncertainties of ground motions on CCBs. Thus, this study adopts the performance-based seismic assessment in a probabilistic framework to evaluate the seismic fragility of CCBs considering NCTE. For this purpose, a numerical model of a typical tall-pier CCB across a V-shaped canyon is constructed using OpenSees. Eighteen ground motions combined with NCTE are simulated using the region-matching method. Peak ground acceleration (PGA), spectral acceleration at the fundamental period T1 (Sa(T1)), and peak ground velocity (PGV) are compared to determine the optimal intensity measure (IM). The probabilistic seismic demand models and fragility curves are constructed. The results show that PGV is the optimal IM for ground motions considering NCTE. The NCTE can significantly increase the damage probability of CCBs. The damage probability of the side bearing is the most sensitive to NCTE among the vulnerable components. The side pier bearings and the side piers on the illuminated canyon side may be the most vulnerable components considering the NCTE effect.
Nano-Micro Letters•2025•DOI: 10.1007/s40820-025-01820-2
Developing innovative resource utilization strategies to achieve sustainable recycling of waste-to-fuel is highly desirable, yet the design of cost-effective bifunctional catalysts with dual high-efficiency remains unexplored. While the Fenton-like reaction relies on enhancing peroxymonosulfate (PMS) adsorption and accelerating interfacial electron transfer to improve kinetic rates, CO2 reduction is constrained by sluggish kinetics and competing hydrogen evolution reaction. Herein, we construct a bifunctional catalyst (NiFe-BNC) featuring dual-atomic active sites by introducing boron atoms into a biomass-derived chitosan substrate rich in functional groups, which optimizes atomic coordination environments. In situ experiments and density functional theory calculations reveal that B-atom modulation facilitates carbon substrate defect enrichment, while the charge-tuning effect between metal sites and "boron electron bridge" optimizes PMS adsorption configurations. This synergistic effect facilitates the interfacial electron transfer and enhances the CO2 adsorption capacity of NiFe-BNC by 6 times that of NiFe-NC. The obtained NiFe-BNC exhibits significantly enhanced catalytic activity and selectivity, realizing 99% efficient degradation of volatile organic pollutants in the flowing phase within 2 h and stable mineralization exceeding 60%, while achieving a large current density of 1000 mA cm−2 and CO Faraday efficiency of 98% in the flow electrolytic cell. This work innovatively paves a new way for the rational design of cost-effective functional catalysts to achieve carbon cycle utilization.