Hasil untuk "Materials of engineering and construction. Mechanics of materials"

Gabriel A. Garcia, Giovana S. Barbosa, Rafaela R. Cunha et al.

Zirconium-based conversion coatings provide an environmentally friendly, chromate-free alternative to traditional phosphating and chromating processes for enhancing the corrosion protection of metal substrates. This study investigates the formation and characterization of zirconium-based conversion coatings (Zr-CC) on AA3105-H16. The coatings were produced by immersion in an hexafuorozirconic acid (H2ZrF6) solution and characterized using SEM-FEG, SEM/EDS, and Raman spectroscopy. Considering that the incorporation of organic and/or inorganic additives can enhance the anticorrosive performance of Zr-CCs, electrochemical techniques were employed to assess the influence of Cu2+ ions on corrosion resistance in a sodium chloride medium. The results indicate that, under the tested conditions, Cu2+ ions act as precursors for film formation, increasing the open-circuit potential and decreasing the coating formation time. However, coatings formed in the presence of Cu2+ ions exhibited lower corrosion resistance, revealing a detrimental effect on anticorrosive performance.

Iman Peivaste, Salim Belouettar, Francesco Mercuri et al.

Artificial Intelligence is rapidly transforming materials science and engineering, offering powerful tools to navigate complexity, accelerate discovery, and optimize material design in ways previously unattainable. Driven by the accelerating pace of algorithmic advancements and increasing data availability, AI is becoming an essential competency for materials researchers. This review provides a comprehensive and structured overview of the current landscape, synthesizing recent advancements and methodologies for materials scientists seeking to effectively leverage these data-driven techniques. We survey the spectrum of machine learning approaches, from traditional algorithms to advanced deep learning architectures, including CNNs, GNNs, and Transformers, alongside emerging generative AI and probabilistic models such as Gaussian Processes for uncertainty quantification. The review also examines the pivotal role of data in this field, emphasizing how effective representation and featurization strategies, spanning compositional, structural, image-based, and language-inspired approaches, combined with appropriate preprocessing, fundamentally underpin the performance of machine learning models in materials research. Persistent challenges related to data quality, quantity, and standardization, which critically impact model development and application in materials science and engineering, are also addressed.

Zonglin Yi, Yi Zhou, Hao Liu et al.

Abstract Accurate prediction of practical reduction electrode potentials (E red) of electrolyte solvents of electrochemical energy storage devices relies on calculating the Gibbs free energy in their reduction reaction. However, the emergence of new electrolyte solvents and additives leaves most of the reaction mechanisms unveiled. Here, we provide a machine-learning-assisted workflow of thermodynamically quantified E red prediction for electrolyte solvents. A computational hydrogen electrode model based on density functional theory calculation is generalized for calculating the reaction free energy of electrochemical elementary steps. Machine-learning models are trained based on the organic and inorganic electrolyte solvents that possess experimentally identified reduction mechanisms. Validation of the best-scoring model is conducted by experimental validation of 6 additional solvents. Multiple thermodynamics features are found impactful on E red through different chemical bonding with reaction intermediates. This workflow enables accurate E red prediction for electrolyte solvents without identified reduction mechanisms, and is widely applicable in the electrochemical energy storage area.

Youbo Nan, Xiutong Wang, Hui Xu et al.

Abstract Triboelectric nanogenerator (TENG) is an emerging wave energy harvesting technology with excellent potential. However, due to issues with sealing, anchoring, and difficult deployment over large areas, TENG still cannot achieve large‐scale wave energy capture. Here, a submerged and completely open solid–liquid TENG (SOSL‐TENG) is developed for ocean wave energy harvesting. The SOSL‐TENG is adapted to various water environments. Due to its simple structure, it is easy to deploy into various marine engineering facilities in service. Importantly, this not only solves the problem of difficult construction of TENG networks at present, but also effectively utilizes high‐quality wave energy resources. The working mechanism and output performance of the SOSL‐TENG are systematically investigated. With optimal triggering conditions, the transferred charge (Qtr) and short‐circuit current (Isc) of SOSL‐TENG are 2.58 μC and 85.9 μA, respectively. The wave tank experiment is taken for fully demonstrating the superiority of the SOSL‐TENG network in large‐scale collection and conversion of wave energy. Due to the excellent output performance, TENG can harvest wave energy to provide power for various commercial electronic devices such as LED beads, hygrothermograph, and warning lights. Importantly, the SOSL‐TENG networks realizes self‐powered for electrochemical systems, which provides a direction for energy cleanliness in industrial systems. This work provides a prospective strategy for large‐scale deployment of TENG applications, especially for harvesting wave energy in spray splash zones or at the surface of the water.

Huiyuan Shi, Jie Guo, Zhiyuan Xia et al.

Interfacial spalling is a common failure mode in fiber-reinforced polymer (FRP) strengthened concrete structures, and interfacial bonding defects are one of the major causes of such damage. These early-stage defects are difficult to identify through visual inspection, highlighting the importance of developing non-contact, non-destructive testing (NDT) methods for detecting interfacial bonding. In this study, the digital image correlation (DIC) technique was employed to detect early bonding at the interface of FRP-strengthened concrete beams. Deformation was induced by varying the surface temperature of the specimens, and image stitching and analysis were performed to obtain second principal strain maps during thermal loading. The interfacial bonding defects were identified based on strain concentration zones in the strain field. A finite element model was developed to simulate the thermal loading process, and the simulation results were found to be consistent with experimental observations. The study confirms the feasibility of using DIC-based thermal deformation analysis for detecting interfacial bonding in FRP-strengthened concrete structures. The results show that larger defect size and greater defect thickness lead to more pronounced strain concentration. Thinner FRP layers improve defect detectability, while the effect of anchorage method on detection results is negligible.

Chiyoung Kim, Ryan Jacobs, Jack H. Duffy et al.

Proton ceramic fuel cells (PCFCs) achieve high efficiency at reduced operating temperatures, but their performance is often limited by slow oxygen reduction reaction (ORR) kinetics at the cathode. The BaCoFeZrY (BCFZY) perovskite family is a promising triple-conducting air-electrode material, yet the role of Y dopants in governing oxygen transport remains unclear. In this study, we examine the effect of Y content on oxygen conductivity in three compositions: BCFZ, BCFZY0.1, and BCFY. Oxygen conductivity was evaluated from the product of oxygen tracer diffusivity and oxygen defect concentration. Ab initio molecular dynamics simulations were used to determine tracer diffusivity and migration energies, while defect concentrations were estimated from reference data. Y doping slightly decreases oxygen conductivity from BCFZ to BCFZY0.1, from 337 to 203 mS/cm at 500 C, with activation energies of 0.155 and 0.172 eV. BCFY shows much lower conductivity (99 mS/cm) and a higher activation energy of 0.261 eV. Computed conductivities are higher and more Arrhenius-like than experimental values, suggesting that microstructural features such as grain boundaries strongly limit oxygen transport in real materials. A series-circuit model combining bulk conductivity and fitted grain-boundary parameters provides semi-quantitative agreement with experiment. These results clarify the role of Y doping in oxygen transport and provide insight for optimizing cathode performance in PCFCs.

Yu-Mi Wu, Sihun Lee, Yufeng Xi et al.

Moiré superlattice in two-dimensional (2D) materials provides a powerful platform to engineer emergent electronic states, yet the construction of moiré superlattices remains lab-scale, involving much trial and error and with little control. Here, we demonstrate the construction of a heterostrain-induced moiré superlattice in transition metal dichalcogenides using a scalable process that deterministically induces strain to 2D materials. By applying patterned thin-film stressors and probing the resulting structures with scanning transmission electron microscopy, we directly resolve the induced heterostrain, lattice deformations, and stacking variations that produce the moiré superlattice. We find that uniaxial and biaxial heterostrain give rise to distinct moiré patterns, including stripes and distorted hexagonal patterns. With this approach, we create in-plane polar distortions and thus in-plane polarization at the domain boundaries of the moiré superlattice in MoS$_2$. The deterministic and scalable construction of moiré patterns using a well-established scalable process opens opportunities to design new moiré geometries in 2D materials.

Aytac Celik

The inherent flexibility of two dimensional materials allows for efficient manipulation of their physical properties through strain application, which is essential for the development of advanced nanoscale devices. This study aimed to understand the impact of mechanical strain on the magnetic properties of two dimensional materials using Monte Carlo simulations. The effects of several strain states on the magnetic properties were investigated using the Lennard Jones potential and bond length-dependent exchange interactions. The key parameters analyzed include the Lindemann coefficient, radial distribution function, and magnetization in relation to temperature and magnetic field. The results indicate that applying biaxial tensile strain generally reduces the critical temperature. In contrast, the biaxial compressive strain increased Tc within the elastic range, but decreased at higher strain levels. Both compressive and tensile strains significantly influence the ferromagnetic properties and structural ordering, as evidenced by magnetization hysteresis. Notably, pure shear strain did not induce disorder, leaving the magnetization unaffected. In addition, our findings suggest the potential of domain-formation mechanisms. This study provides comprehensive insights into the influence of mechanical strain on the magnetic behavior and structural integrity of 2D materials, offering valuable guidance for future research and advanced material design applications.

Jihoon Keum, Kai-Xuan Zhang, Suik Cheon et al.

Magnetization switching by charge current without a magnetic field is essential for device applications and information technology. It generally requires a current-induced out-of-plane spin polarization beyond the capability of conventional ferromagnet/heavy-metal systems, where the current-induced spin polarization aligns in-plane orthogonal to the in-plane charge current and out-of-plane spin current. Here, we demonstrate a new approach for magnetic-field-free switching by fabricating a van-der-Waals magnet and oxide Fe3GeTe2/SrTiO3 heterostructure. This new magnetic-field-free switching is possible because the current-driven accumulated spins at the Rashba interface precess around an emergent interface magnetism, eventually producing an ultimate out-of-plane spin polarization. This interpretation is further confirmed by the switching polarity change controlled by the in-plane initialization magnetic fields with clear hysteresis. We successfully combined van-der-Waals magnet and oxide for the first time, especially taking advantage of spin-orbit torque on the SrTiO3 oxide. This allows us to establish a new way of magnetic field-free switching. Our work demonstrates an unusual perpendicular switching application of large spin Hall angle materials and precession of accumulated spins, and in doing so, opens up a new field and opportunities for van-der-Waals magnets and oxide spintronics.

Jiayu Xie, Xin Ma, Wenjun Kuang

FeCrAl alloy, a promising candidate for accident tolerance fuel (ATF) cladding, has relatively low resistance to general corrosion in high temperature water. To improve the corrosion resistance, a continuous Al2O3 layer was formed on the surface of FeCrAl alloy through gaseous pre-oxidation. It was found that such treatment can significantly improve its corrosion resistance in high temperature hydrogenated water. The thickness of inner oxide layer after exposure to 320 °C hydrogenated water for 950 h was reduced by ∼40%. In addition, the size and density of outer oxide particles were also decreased. However, the Al2O3 film pre-formed on FeCrAl alloy had poor stability in high temperature water and its long-term effect needs to be further evaluated.

Jingfan Wang, Xingxing Wang, Xiying Ma et al.

Tissue self-renewal is crucial for ocular diseases such as corneal damage and retinal holes. In this study, a novel Poly (lactic-co-glycolic acid) (PLGA) electrospinning nanofibrous scaffold (PLGAENS), loaded with mesenchymal stem cells-derived extracellular vesicles (MSC-EVs), was developed to accelerate the healing of the cornea and retina. In-vitro experiments confirmed the supportive properties of PLGAENS, demonstrating its ability to promote cellular proliferation, migration, and extension. In the rat corneal alkali burn model and rabbit retinal hole model, MSC-EVs modified PLGAENS (PLGAMSC-EVs) accelerated the restoration of the corneal epithelium and stroma, as well as the closure of retinal holes. Additionally, miR-21-5p was identified as being enriched in MSC-EVs. Mechanistically, miR-21-5p suppressed scar formation by targeting the programmed cell death protein 4 (PDCD4) gene, reducing fibrosis and the expression of collagen-related genes, which helped maintain corneal transparency and retinal integrity. Overall, these findings underscored the potential of PLGAMSC-EVs in promoting ocular wound healing and suggested a promising new therapeutic strategy for the clinical treatment of corneal damage and retinal holes.

V.M. Calinescu, M. Oproescu, V.G. Iana et al.

Christopher Tyler Cox, Jakob Haynes, Christopher Duffey et al.

Understanding of the formation and evolution of the Solar System requires understanding key and common materials found on and in planetary bodies. Mineral mixing and its implications on planetary body formation is a topic of high interest to the planetary science community. Previous work establishes a case for the use of Optical PhotoThermal InfraRed (O-PTIR) in planetary science and introduces and demonstrates the technique's capability to study planetary materials. In this paper, we performed a measurement campaign on granular materials relevant to planetary science, such as minerals found in lunar and martian soils. These laboratory measurements serve to start a database of O-PTIR measurements. We also present FTIR absorption measurements of the materials we observed in O-PTIR for comparison purposes. We find that the O-PTIR technique suffers from granular orientation effects similar to other IR techniques, but in most cases, is is directly comparable to commonly used absorption spectroscopy techniques. We conclude that O-PTIR would be an excellent tool for the purpose of planetary material identification during in-situ investigations on regolith and bedrock surfaces.

Jacinto Ulloa, Laurent Stainier, Michael Ortiz et al.

This paper explores the role of generalized continuum mechanics, and the feasibility of model-free data-driven computing approaches thereof, in solids undergoing failure by strain localization. Specifically, we set forth a methodology for capturing material instabilities using data-driven mechanics without prior information regarding the failure mode. We show numerically that, in problems involving strain localization, the standard data-driven framework for Cauchy/Boltzmann continua fails to capture the length scale of the material, as expected. We address this shortcoming by formulating a generalized data-driven framework for micromorphic continua that effectively captures both stiffness and length-scale information, as encoded in the material data, in a model-free manner. These properties are exhibited systematically in a one-dimensional softening bar problem and further verified through selected plane-strain problems.

Rensong Huang, Hongfu Yang, Shanju Zheng et al.

The evolution mechanism of the second phase in the homogenization process of Al-Zn-Mg-Cu aluminum alloy was thoroughly investigated. The results revealed that the phase transition of Mg(Zn, Cu, Al)2 to S(Al2CuMg) occurs due to the interdiffusion between Zn and Al atoms at the interface during homogenization at 420 °C for 15 to 30 min. Additionally, the dissolution of S(Al2CuMg) into the Al- matrix is governed by the interdiffusion of (Mg, Cu atoms) and Al atoms. Notably, the θ(Al2Cu) phase plays a crucial role as an intermediate transition phase facilitating the dissolution of S(Al2CuMg) into the Al- matrix. These findings significantly contribute to our understanding of the complex processes involved in the phase transformations during the homogenization of the Al-Zn-Mg-Cu aluminum alloy.

Jing Xu, Juan Yang, Zhongteng Wang et al.

Quantitative identification of mixed-valence metal ions is essential for gaining deeper insights into critical chemical and biological processes in environmental science, chemical engineering, and biological systems. However, a simple approach of quantitative identification mixed-valence metal ions in solution has remained a challenge. In this study, we have experimentally observed a significant linear correlation (R2 = 0.99) between the concentration of high-valence metal ions (using iron ions as an example) and the fluorescence intensity of graphene quantum dots (GQDs). Utilizing the distinct fluorescence responses of GQDs to high-valence and low-valence metal ions, reliable quantitative detection of mixed-valence metal ions has been successfully achieved. Remarkably, we introduced real-time monitoring of mixed-valence metal ions, revealing a shift from a molar ratio of approximately 4.0 to 2.0. Density functional theory calculations have revealed significant differences in charge transfer between high-valence and low-valence states of metal ions adsorbed onto GQDs. Furthermore, the versatility of this method can extend to various types of GQDs and metal ions, highlighting its universal applicability. This work presents a simple, convenient, and cost-effective approach for quantitatively identifying mixed-valence metal ions in solution, offering a new avenue and opportunity for applications in biochemistry, environmental science, catalysis and materials science.

Ganeshprabhu Parvathikumar, Gurukarthik Babu Balachandran, Brintha Sahadevan

The utilization of industrial waste materials in concrete compensates the shortage of natural resources by not only solving the problem due to disposal of wastes but also by developing alternative solutions to protect the environment as well as reduction in the area requirement for landfill. The concrete made with such wastages using less energy during its production and eco-friendly is called as Green Concrete. Variety of industrial wastes is employed as whole or partial substitution for coarse or fine aggregate. Steel mill scale is one such kind of waste materials produced as a result of hot process of rolling of steel in steel companies with rich source of iron content with least impurities. This research study investigates the viability of adopting steel mill scale as a partial substitute material for fine aggregate (M-sand). The current study investigates the influence on fresh and hardened concrete paving blocks and its properties, when M-sand is replaced at 0%, 20%, 40%, 60%, 80%, and 100% with steel mill scale using a mix ratio of 1:1.6:2.1 at sustained water-cement ratio value of 0.5 and target strength at 28 days of 30 Mega Pascal. Physical and chemical characterisation of the materials, concrete compressive strength, concrete split tensile strength, water absorption, and also micro-structural examination of hardened paving blocks are experimentally investigated. Results suggest that 60% of the replacements outperformed the originals. The research findings point towards the feasibility of producing paving blocks from scrap steel mill scale for enhancing environmentally friendly construction practices and sustainable pavement infrastructure.

Mohammad Karimzadeh, Deekshith Basvoju, Aleksandar Vakanski et al.

Additive Manufacturing (AM) is a transformative manufacturing technology enabling direct fabrication of complex parts layer-be-layer from 3D modeling data. Among AM applications, the fabrication of Functionally Graded Materials (FGMs) has significant importance due to the potential to enhance component performance across several industries. FGMs are manufactured with a gradient composition transition between dissimilar materials, enabling the design of new materials with location-dependent mechanical and physical properties. This study presents a comprehensive review of published literature pertaining to the implementation of Machine Learning (ML) techniques in AM, with an emphasis on ML-based methods for optimizing FGMs fabrication processes. Through an extensive survey of the literature, this review article explores the role of ML in addressing the inherent challenges in FGMs fabrication and encompasses parameter optimization, defect detection, and real-time monitoring. The article also provides a discussion of future research directions and challenges in employing ML-based methods in AM fabrication of FGMs.

Felix Wiesner, Rory Hadden, Susan Deeny et al.

Daniyar Akhmetov, Sungat Akhazhanov, Ainur Jetpisbayeva et al.

The article presents the results of laboratory experiments investigating the necessity and expediency of disperse reinforcement of self-compacting concrete (SCC) to increase its physical and technical parameters and the study of deformative properties of SCC with the use of fibers. For collaboration with manufacturers to improve physical and mechanical properties and durability, to deduce basic laws, researchers on the basis of previously published results, offered disperse reinforcement of SСС by polypropylene fibers of 6, 9, 12, 15 mm in size and quantity from 0.5 to 2 kg per 1 m3 of concrete mixture. From the work done it can be concluded that the addition of 1–2 kg per 1 m3 of fiber with 9÷15 mm in size improves the physical and technical properties of SCC, such as flexural strength by 10%, and shrinkage deformations reduced to 75% compared to the concrete without fiber. In the course of this study, it was found that the disperse reinforcement with low-modulus fiber increases the characteristics of SCC in production. Based on the results obtained, practical recommendations for the optimal size and amount of fiber in SCC were presented in order to derive the optimal price-quality ratio, as well as to improve the quality of concrete works at high temperatures > 20 °C.