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Volume 2, Issue 2, 2025

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Curved multi-layer beams, such as leaf springs, are widely used in vehicle suspension systems for both road and rail vehicles in automotive industry due to their capacity for high loads and their vibrational damping properties. To design suspension systems that experience a large number of load types and complexities of friction, we must first understand the nonlinear dynamic behavior of curved beams. In this paper, the governing equations for the nonlinear vibrations of curved two-layer beams in the presence of interlayer slip are first derived. Then, the characteristic equation, the longitudinal and transverse mode shapes of the beam, are determined independently using eigenvalue problem solutions. Subsequently, using the calculated mode shapes, different phases of the dynamics of these structures are investigated, taking into account interlayer friction. The results of numerical simulations are compared and validated with finite element analysis using ANSYS software. The results show that the dynamic behavior of curved two-layer beams experiences chaotic regimes after initial slip. Different regimes of periodic, quasi-periodic and chaotic motions are found in the dynamics of the system.

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The effectiveness of single-axis solar tracking in enhancing the performance of flat-plate solar collectors (FPSCs) has been widely acknowledged, particularly under clear-sky conditions. However, the precision of solar tracking systems—governed by the electro-mechanical transmission's discrete rotation step size—has a critical impact on energy yield. In this study, the influence of varying rotation step sizes on the incident solar irradiance received by flat-plate collectors with single-axis tracking (SAT) has been numerically investigated using the EnergyPlus simulation environment. Eight discrete step sizes—1°, 2°, 5°, 10°, 15°, 30°, 45°, and 90°—were examined under clear-sky conditions on July 26, using meteorological data specific to Kragujevac, Serbia. The tracking system was configured to follow the solar trajectory along the east–west (E–W) direction, rotating around a north–south (N–S) inclined axis. Results demonstrated that incident solar irradiance was significantly enhanced—by over 35%—when rotation step sizes ranged between 1° and 15°, compared to fixed (non-tracking) collectors. Slight reductions in performance were observed for step sizes of 30° (34.26% improvement) and 45° (32.95%), with the lowest gain (23.04%) associated with the coarsest resolution of 90°. Although dual-axis tracking (DAT) systems provide superior irradiance capture, single-axis systems offer substantial advantages in residential and small-scale applications due to their lower capital investment, simpler design, reduced maintenance requirements, and greater architectural integration potential. These findings underscore the importance of optimizing rotation step size in the design and deployment of cost-effective, energy-efficient solar tracking systems. In light of increasingly stringent energy performance directives within the European Union, the deployment of optimally configured SAT systems is expected to expand across the residential sector.

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The widespread adoption of electric vehicles (EVs) has brought about critical challenges in brake rotor performance, primarily attributed to the reduced reliance on conventional friction braking systems. This decreased usage, owing to the predominant application of regenerative braking, has inadvertently increased the susceptibility of brake rotors—particularly those manufactured from grey cast iron (GCI)—to corrosion and non-traditional wear mechanisms due to extended exposure to environmental elements. These challenges are compounded by the global imperative for sustainable transportation solutions, as emphasized in the European Union (EU)’s roadmap for climate-neutral mobility. In this context, the development and implementation of sustainable strategies to improve the wear and corrosion resistance of EV brake rotors have become paramount. This review synthesizes recent advancements in environmentally conscious approaches, including the application of eco-friendly surface treatments, alloying modifications, microstructural engineering, and solid or dry lubrication techniques tailored for GCI rotors. The analysis extends to the evaluation of scalability, cost-efficiency, tribological stability, and environmental compatibility over the rotors' service life. Particular attention is devoted to emergent solutions such as bio-inspired multifunctional coatings, integration of intelligent condition-monitoring technologies, and rotor design optimized through data-driven predictive modelling. The necessity for robust life cycle assessments (LCA) is underscored, aiming to holistically quantify environmental impact from raw material extraction through end-of-life disposal or recycling. Key research gaps are identified, including the limited real-world validation of novel materials under EV-specific load profiles and insufficient understanding of synergistic degradation modes under mixed braking regimes. It is suggested that a multidisciplinary research agenda—merging materials science, tribology, electrochemistry, and intelligent systems—is essential to advance the next generation of high-performance, low-impact braking solutions. In doing so, a comprehensive framework for sustainable brake rotor innovation in EVs can be established, aligning material resilience with broader environmental and regulatory goals.

Open Access
Research article
Influence of Prestrain on Microstructural Evolution and Corrosion Behavior of Copper-Based Alloys
Muhssn Hamzah Shamky ,
Haider Zghair Jumaah ,
Talib Ali Ridha Elias ,
Noaman Abdulrahman Karam
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Available online: 06-29-2025

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The influence of prestrain on the microstructural evolution and corrosion behaviour of copper-based alloys has been systematically investigated to elucidate the mechanisms by which mechanical preconditioning enhances structural integrity and electrochemical stability. Prestrain, applied prior to subsequent thermomechanical treatments, has been found to significantly alter dislocation density, grain size distribution, phase transformation pathways, and precipitate morphology and distribution. These changes collectively promote grain refinement and the formation of nanocrystalline domains, thereby improving both strength and ductility. Enhanced effects have been observed in Cu–Cr–Zr and Cu–Al–Ni alloys, particularly when prestrain is introduced via cold rolling or friction stir processing (FSP). In these systems, microstructural stability during post-deformation ageing is markedly improved due to the suppression of grain coarsening and the controlled precipitation of strengthening phases. Moreover, prestrain modifies the local chemical and crystallographic environment in a manner that critically impacts electrochemical behavior. Intermediate levels of mechanical stress have been shown to improve corrosion resistance by facilitating the formation of uniform, adherent passive films, while excessive strain introduces microstructural heterogeneities that serve as initiation sites for intergranular and stress corrosion cracking. These phenomena were characterized using X-ray diffraction, scanning and transmission electron microscopy (TEM), and electrochemical techniques including potentiodynamic polarization and electrochemical impedance spectroscopy. The interplay between mechanical preconditioning, microstructural refinement, and corrosion mechanisms has been clarified, offering insights into process–structure–property relationships. The findings hold particular relevance for the design and optimization of copper alloys in high-performance applications such as electronic interconnects, biomedical implants, and aerospace components, where dimensional stability, chemical resilience, and machinability are of paramount importance. The study underscores the critical role of prestrain not only as a structural refinement tool but also as a means of tailoring corrosion resistance through controlled microstructural engineering.

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Prompt and proper maintenance management helps extend the operation lifespan of workplace equipment to achieve production targets without interrupting the production process. In this connection, accurate prediction of the reliability-based scheduled maintenance (SM) time intervals of equipment is essential. The current research aimed to develop a reliability-based model to forecast the maintenance time intervals specifically for Load-Haul-Dumper (LHD) underground mining equipment. The series configuration system of the Reliability Block Diagram (RBD) model was adopted to evaluate the overall system reliability for each LHD machine. The reliability percentage of each sub-system was ascertained through a reliability analysis of a complex repairable system. To build the required Artificial Neural Network (ANN) model for analysis, the “Isograph Reliability Workbench 13.0” software was adopted to estimate the input layers of reliability ($R$) and the best-fit distribution parameters, such as the scale parameter ($\eta$), shape parameter ($\beta$), and location parameter ($\gamma$). The ANN model created was trained using the Levenberg-Marquardt (LM) learning algorithm. The predicted SM values were extremely close to the calculated values as indicated by the optimal $R^2$ value of 0.9998. The outcome demonstrated that the ANN model could improve the performance of the equipment with a major impact on the initial weight optimization. Suggestions were made for the industry practitioners to enhance the dependability of the equipment with planned maintenance procedures designed by the proposed ANN, with possible potential to be explored by other equipment users.
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