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

Elaheh Janbezar, Hemayat Shekaari, Mohammed Taghi Zafarani-Moattar

Abstract This study addresses the challenge of achieving long-term colloidal stability in SiO2 nanofluids, a critical barrier for their practical applications, by investigating the stabilizing effects of surface-active ionic liquids (SAILs) on aqueous SiO2 nanoparticle dispersions. The purpose is to evaluate how SAILs specifically (2-hydroxyethyl)ammonium oleate (HEA-Ole), bis(2-hydroxyethyl)ammonium oleate (BHEA-Ole), and tris(2-hydroxyethyl)ammonium oleate (THEA-Ole) can enhance SiO2 stability beyond typical literature reports of less than 20 days. The stability was assessed through excess molar volume ( $$V_{m}^{E}$$ ), viscosity (η), density (ρ), DLS, zeta potential, surface tension, COSMO results, and visual observation over 60 days. The viscosity modeled by Eyring-mNRF and Eyring-NRTL, while density data were fitted with Redlich–Kister, polynomial, Ott, and PC-SAFT models. THEA-Ole demonstrated superior stabilization of SiO2, particularly after-critical micelle concentration (CMC), with minimal sedimentation, optimal dispersity via DLS, and a high zeta potential. Viscosity data aligned with Einstein, Batchelor, Brinkman, and Lundgren prediction models, $$V_{m}^{E}$$ and surface tension measurement indicated stable trends in THEA-Ole, and PC-SAFT showed the lowest ARD% for THEA-Ole nanofluids, confirming strong SiO2 interactions. THEA-Ole nanofluids provide exceptional SiO2 stability over 60 days, outperforming conventional surfactants and addressing key limitations in nanofluid dispersion for extended applications.

Qi Wang, Hechang Lei, Yanpeng Qi et al.

Topological quantum materials with kagome lattice have become the emerging frontier in the context of condensedmatter physics. Kagome lattice harbors strongmagnetic frustration and topological electronic states generatedby the unique geometric configuration.Kagomelattice has the peculiar advantages in the aspectsofmagnetism, topology aswell as strong correlationwhenthe spin, charge,ororbit degreesof free is introduced, and providing a promising platform for investigating the entangled interactionsamongthem. In this paper, we will systematically introduce the research progress on the kagome topological materials and give a perspective in the framework of the potential future development directions in this field.

Ehsan Kasehchi, Mohammad Ali Arjomand, Mohammad Hadi Alizadeh Elizei

The experimental study of geopolymeric stabilized samples based on ceramic waste powder (CWP) and sodium hydroxide solution acting as an alkali activator was investigated in the present research to evaluate the possibility of geopolymeric stabilization of silty sand soil as a sustainable method for improving the mechanical properties of inshore sand soils. X-ray fluorescence spectroscopy (XRF) was employed to analyze and determine the chemical components of the CWP and natural soil. The effect of four factors on the unconfined compression strength (UCS) and failure strain (Ɛf) of silty sand soil, including CWP content (0–24%), NaOH solution concentration (0–15 M), the curing time (7, 28, and 91 days), and the initial curing temperature (25°C and 70°C), were investigated. The results demonstrated a substantial increase in both UCS and Ɛf for geopolymeric stabilized samples in comparison to natural soil and the soil that was stabilized with 5% ordinary Portland cement (OPC). The UCS and Ɛf values of the 28-day-cured optimal sample (CWP = 15% and NaOH solution concentration = 6 M) in comparison with natural soil increased from 0.080 to 2.22 MPa and from 2.31% to 5.45%, respectively. Moreover, the UCS value in this sample was 1.75, 1.81, and 1.29 times higher than the stabilized soil with 5% OPC for each curing time. Without an alkali activator, CWP addition to the soil had no effect on UCS at all curing times. However, when a 2 M NaOH solution was added to the soil without CWP, the UCS of this sample rose to 0.36 MPa after 7 days of curing. The UCS of geopolymeric stabilized samples experienced growth from 1.27 to 2.04 times by shifting the initial curing temperature from 25°C to 70°C. Through the use of energy-dispersive X-ray (EDX) spectra and scanning electron microscope (SEM) photomicrograph, the microstructure of stabilized samples was inspected. SEM photomicrographs corroborated the UCS test findings, and EDX analysis confirmed the high quality of the aluminosilicate gels' growth and production. To sum up, soil stabilization using CWP geopolymer is a cost-effective, environmentally friendly method that reduces the consumption of natural resources and energy.

Dmytro V. Pavlenko, Daria V. Tkach, Yevgen V. Vyshnepolskyi et al.

The technology of manufacturing aluminum alloy workpieces using additive friction stir deposition (AFS-D) has been thoroughly investigated. The ambiguous influence of deformation processing modes on the material density was found. Examination of the microstructure in the central zone of the specimens reveals the absence of microdefects typically associated with workpieces obtained through casting or powder metallurgy methods. It has been observed that the distribution of microhardness is significantly affected by the direction of specimen construction, with approximately a 20% difference in values between the periphery and the central part of the specimen. Specimens produced using the AFS-D method exhibit a homogeneous microstructure characteristic of deformable aluminum alloys. Notably, a uniform distribution of intermetallides on the specimen surface has been identified. This outcome is likely a result of the alloy undergoing recrystallization during the severe plastic deformation process, leading to the formation of an ultradisperse structure. It is important to emphasize that the selection of technological parameters for AFS-D should consider not only the magnitude of pressure and deformation but also the deformation speed.

Connor Edsall, Laura Huynh, T. Hall et al.

Histotripsy is a non-thermal focused ultrasound ablation method that destroys tissue through the generation and activity of acoustic cavitation bubble clouds. Intrinsic threshold histotripsy uses single-cycle pulses to generate bubble clouds when the dominant negative pressure phase exceeds an intrinsic threshold of ~25–30 MPa. The ablation efficiency is dependent upon the size and density of bubbles within the bubble cloud. This work investigates the effects of dual-frequency pulsing schemes on the bubble cloud behavior and ablation efficiency in intrinsic threshold histotripsy. A modular 500 kHz:3 MHz histotripsy transducer treated agarose phantoms using dual-frequency histotripsy pulses with a 1:1 pressure ratio from 500 kHz and 3 MHz frequency elements and varying arrival times for the 3 MHz pulse relative to the arrival of the 500 kHz pulse (−100 ns, 0 ns, and +100 ns). High-speed optical imaging captured cavitation effects to characterize bubble cloud and individual bubble dynamics. The effects of dual-frequency pulsing on lesion formation and ablation efficiency were also investigated in red blood cell (RBC) phantoms. Results showed that the single bubble and bubble cloud size for dual-frequency cases were intermediate to published results for the component single frequencies of 500 kHz and 3 MHz. Additionally, bubble cloud size and dynamics were shown to be altered by the arrival time of the 3 MHz pulse with respect to the 500 kHz pulse, with more uniform cloud expansion and collapse observed for early (−100 ns) arrival. Finally, RBC phantom experiments showed that dual-frequency exposures were capable of generating precise lesions with smaller areas and higher ablation efficiencies than previously published results for 500 kHz or 3 MHz. Overall, results demonstrate dual-frequency histotripsy’s ability to modulate bubble cloud size and dynamics can be leveraged to produce precise lesions at higher ablation efficiencies than previously observed for single-frequency pulsing.

Hsiao-Tsun Chien, Jia-Ruey Chang, Hui-Mi Hsu

Steel furnace slag containing heavy metal components is covered by asphalt cement when it is used to replace natural aggregates in road paving. When such a pavement deteriorates as a result of wear by people and vehicles as well as washing by rain, the aggregates are worn away and the heavy metal components within can overflow on the road’s surface, forming rust spots. This phenomenon has been observed on many roads, leading the general public to question the validity of using steel furnace slag and whether this is in violation of a contract with the contractor. However, it is known from literature that such rust spots on a road surface may also be caused by natural minerals such as pyrite that are contained in natural aggregates. Unlike cement concrete, the slag cannot be separated from the mixture after hardening; however, the asphalt cement can be separated from the aggregates by using a solvent. In this study, separated aggregates are tested for pH value, magnetic attraction, and elemental composition in order to assess the usability of slag. Based on the findings and the characteristics of steel furnace slag, this paper proposes a method for detection of steel furnace slag in asphalt concrete, which is divided into two stages. In the first stage, core samples of asphalt concrete are obtained from the road site. The asphalt cement is separated from the aggregates according to AASHTO T164 and then the separated aggregates are analyzed in pH value and magnetic attraction tests. When one or both of the tests indicate steel furnace slag characteristics, that is, alkalinity or magnetism, then it is possible that the asphalt concrete sample contains steel furnace slag, and should be tested in the second stage for further confirmation. In the second stage, the separated aggregates are grinded to less than 0.075 mm (No. 200) and their elemental composition is analyzed. Based on the composition of steel furnace slag, when the analysis results indicate ≥30 % CaO and ≥10 % Fe2O3, it can be regarded that steel furnace slag has been used in the asphalt concrete.

CHEN Qibo, ZHAO Yongwu, BIAN Da

In order to improve the corrosion resistance of 40Cr steel surface,bis-[7-(triethoxy silicon)propyl]-tetrasulfide(BTESPT),zirconium nitrate and phytic acid were used to prepare silane zirconium salt composite conversion coating with excellent corrosion resistance on the surface of 40Cr steel.The film forming process conditions of silane zirconium salt composite conversion solution were determined by orthogonal tests.The corrosion resistance,morphology,composition and potential characteristics of the composite coating were analyzed by copper sulfate titration,scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR)and electrochemical tests.Results showed that the optimum process of silane zirconium salt composite coating was as follows:silane concentration was 5(volume fraction),zirconium nitrate concentration was 0.75%(mass fraction),pH value of solution was 4,hydrolysis temperature was 25 C,and reaction time was 50 s.Through the results of copper sulfate drop test and electrochemical test,it was found that the corrosion resistance of the composite convesion coating doped with phytic acid was significantly improved compared with that of the silane coating and the silane zirconium salt coating.Through the observation of micro morphology,it was indicated that the addition of phytic acid made up for the defects of the coating,hindered the diffusion of corrosive medium,therefore,enhancing the corrosion resistance of the coating.

Gaurav Vats, Brett Hodges, Andrew J. Ferguson et al.

Metal halide perovskite-based materials have emerged over the past few decades as remarkable solution-processable opto-electronic materials with many intriguing properties and potential applications. These emerging materials have recently been considered for their promise in low-energy memory and information processing applications. In particular, their large optical cross-sections, high photoconductance contrast, large carrier diffusion lengths, and mixed electronic/ionic transport mechanisms are attractive for enabling memory elements and neuromorphic devices that are written and/or read in the optical domain. Here, we review recent progress toward memory and neuromorphic functionality in metal halide perovskite materials and devices where photons are used as a critical degree of freedom for switching, memory, and neuromorphic functionality.

Arka Bandyopadhyay, Nesta Benno Joseph, Awadhesh Narayan

The emergence of the fascinating non-linear Hall effect intrinsically depends on the non-zero value of the Berry curvature dipole. In this work, we predict that suitable strain engineering in layered van der Waals material phosphorene can give rise to a significantly large Berry curvature dipole. Using symmetry design principles, and a combination of feasible strain and staggered on-site potentials, we show how a substantial Berry curvature dipole may be engineered at the Fermi level. We discover that monolayer phosphorene exhibits the most intense Berry curvature dipole peak near 11.8% strain, which is also a critical point for the topological phase transition in pristine phosphorene. Furthermore, we have shown that the necessary strain value to achieve substantial Berry curvature dipole can be reduced by increasing the number of layers. We have revealed that strain in these van der Waals systems not only alters the magnitude of Berry curvature dipole to a significant value but allows control over its sign. We are hopeful that our predictions will pave way to realize the non-linear Hall effect in such elemental van der Waals systems.

Yewei Chen, H. Lei, Quanjun Wang et al.

We study population distributions and lasing actions of N_2^+ driven by femtosecond lasers with various wavelengths, and uncover an efficient ionic excitation mechanism induced by synchronized ionization and multiphoton resonance. Our results show that the strongest N_2^+ lasing appears around 1000 nm pump wavelength. At the optimal wavelength, the pump-energy threshold for air lasing generation is reduced by five folds compared with that required by the previous 800 nm pump laser. Simulations based on the ionization-coupling model indicate that although the Stark-assisted three-photon resonance can be satisfied within a broad pump wavelength range, the optimal pump wavelength arises when the dynamic three-photon resonance temporally synchronizes with the ionization injection. In this case, the ionic dipoles created at each half optical cycle have the same phase. The dipole phase locking promotes the continuous population transfer from ionic ground state to the excited state, giving rise to a dramatic increase of excited-state population. This work provides new insight on the photoexcitation mechanism of ions in strong laser fields, and opens up a route for optimizing ionic radiations.

Zhipeng Lu, M. Stern, Jinqiao Li et al.

Photophoretic levitation is a propulsion mechanism in which lightweight objects can be lifted and controlled through their interactions with light. Since photophoretic forces on macroscopic objects are usually maximized at low pressures, they may be tested in vacuum chambers in close proximity to the chamber floor and walls. We report here experimental evidence that the terrain under levitating microflyers, including the chamber floor or the launchpad from which microflyers lift off, can greatly increase the photophoretic lift forces relative to their free-space (mid-air) values. To characterize this so-called"ground effect"during vacuum chamber tests, we introduced a new miniature launchpad composed of three J-shaped (candy-cane-like) wires that minimized a microflyer's extraneous interactions with underlying surfaces. We compared our new launchpads to previously used wire-mesh launchpads for simple levitating mylar-based disks with diameters of 2, 4, and 8 cm. Importantly, wire-mesh launchpads increased the photophoretic lift force by up to sixfold. A significant ground effect was also associated with the bottom of the vacuum chamber, particularly when the distance to the bottom surface was less than the diameter of the levitating disk. We provide guidelines to minimize the ground effect in vacuum chamber experiments, which are necessary to test photophoretic microflyers intended for high-altitude exploration and surveillance on Earth or on Mars.

S. Sajid, Mukhtar S. Ahmad, E. Khan et al.

The late Cretaceous Kawagarh Formation has been investigated in terms of field observation, and petrographic analysis, to understand the petrography and its impact on the geotechnical properties. The Kawagarh Formation is well exposed among the upper Indus Basin, and has been studied by various workers in different aspects. Kawagarh Formationexposed in Kahi section of Nizampur Basin has been selected in this study to know the behavior of carbonate rocks for engineering purposes. Lithologically, this formation is composed of thick to medium bedded, highly fractured limestone, marls, and dolomitic limestone which has undertaken diagenetic alteration including dolomite, calcite veins, and stylolites. Followed by petrographic analysis which reveals that the Kawagarh limestone is mostly fossiliferouscomprised of a large number of planktonic foraminifera fossils like Globotruncana Hilli and Globotruncana Linneana fossils. Furthermore, to know the impact of petrographic minerals on engineering behavior, mechanical properties in terms of uniaxial compressive strength (UCS) and uniaxial tensile strength (UTS) were also computed by using a universal testing machine (UTM). The resultant mechanical values lie in the strong compressive strength and suggest their usage for various construction purposes. Aggregate degradation tests including water absorption, specific gravity, aggregate impact value, Los angles abrasion, and soundness was also computed according to the International standard organization, ASTM (American Society for testing materials) and British standard. The aggregate values of the Cretaceous Kawagarh Formation are within the defined standard limits and can be used as an aggregate source for different construction engineering projects.

James A Clarke, F. Cavanna, Anne D Crowell et al.

, The actin cytoskeleton is a semiflexible biopolymer network whose morphology is controlled by a wide range of biochemical and physical factors. Actin is known to undergo a phase transition from a single-filament state to a bundled state by the addition of polyethylene glycol (PEG) molecules in sufficient concentration. While the depletion interaction experienced by these biopolymers is well-known, the effect of changing the molecular weight of the depletant is less well understood. Here, we experimentally identify a phase transition in solutions of actin from networks of filaments to networks of bundles by varying the molecular weight of PEG polymers, while holding the concentration of these PEG polymers constant. We examine the states straddling the phase transition in terms of micro and macroscale properties. We find that the mesh size, bundle diameter, persistence length, and intra-bundle spacing between filaments across the line of criticality do not show significant differences, while the relaxation time, storage modulus, and degree of bundling change between the two states do show significant differences. Our results demonstrate the ability to tune actin network morphology and mechanics by controlling depletant size, a property which could be exploited to develop actin-based materials with switchable rigidity. contributed equally in this work. Anne Crowell helped perform all rheological experiments and wrote much of the analysis and methods related to rheology. Justin Houser helped to prototype FRET experiments and provided direct assistance in all FRET data acquisition. Allison Green performed the DLS measurements, fitted the stretched exponential and relaxation time parameters, and provided insight and analysis with Delia Milliron. Kristin Graham helped with acceptor-donor labelling for actin-FRET measurements, along with experimental planning for all FRET data acquisition. Tom Truskett provided insights into the nature of the phase transition and limitations on bundle diameter. Adrianne Rosales was instrumental in conceptually designing rheological experiments and provided consistent feedback and insight as the experiments progressed. Jeanne Stachowiak was instrumental in planning FRET experiments. José Alvarado planned most of the inter-lab experimentation, assisted in the interpretation of all the results, and provided direct feedback on the structure and material of this paper. Lauren Melcher led development and analysis of the simulation and its results with Moumita Das.

Yonatan Kurniawan, Cody Petrie, M. Transtrum et al.

Atomistic simulations are an important tool in materials modeling. Interatomic potentials (IPs) are at the heart of such molecular models, and the accuracy of a model's predictions depends strongly on the choice of IP. Uncertainty quantification (UQ) is an emerging tool for assessing the reliability of atomistic simulations. The Open Knowledgebase of Interatomic Models (OpenKIM) is a cyberinfrastructure project whose goal is to collect and standardize the study of IPs to enable transparent, reproducible research. Part of the OpenKIM framework is the Python package, KIM-based Learning-Integrated Fitting Framework (KLIFF), that provides tools for fitting parameters in an IP to data. This paper introduces a UQ toolbox extension to KLIFF. We focus on two sources of uncertainty: variations in parameters and inadequacy of the functional form of the IP. Our implementation uses parallel-tempered Markov chain Monte Carlo (PTMCMC), adjusting the sampling temperature to estimate the uncertainty due to the functional form of the IP. We demonstrate on a Stillinger–Weber potential that makes predictions for the atomic energies and forces for silicon in a diamond configuration. Finally, we highlight some potential subtleties in applying and using these tools with recommendations for practitioners and IP developers.

Toko Tokunaga, Koji Hagihara, Michiaki Yamasaki et al.

The variation in the mechanical properties with the volume fraction of the long-period stacking ordered (LPSO) phase in directionally solidified (DS) Mg/LPSO two-phase alloys was examined. Unexpectedly, the yield stress of the DS alloys increases non-monotonically with an increase in the volume fraction of the LPSO phase. The LPSO phase is considered an effective strengthening phase in Mg alloys, when the stress is applied parallel to the growth direction. Nevertheless, the highest strength was obtained in alloys with 61–86 vol.% of the LPSO phase, which was considerably higher than that in the LPSO single-phase alloy. It was clarified that this complicated variation in the yield stress was generated from the change in the formation stress of kink bands, which varied with the thickness of the LPSO-phase grains. Furthermore, the coexistence of Mg in the LPSO phase alloy induced the homogeneous formation of kink bands in the alloys, leading to the enhancement of the ‘kink-band strengthening’. The results demonstrated that microstructural control is significantly important in Mg/LPSO two-phase alloys, in which both phases exhibit strong plastic anisotropy, to realize the maximum mechanical properties.

Mohammad Javad Rezaei-Hosseinabadi, Meysam Bayat, Bahram Nadi et al.

Granular column is an attractive mitigation method which is widely used in geotechnical engineering to enhance the bearing capacity, reduce settlement and accelerate consolidation. Utilisation of industrial wastes such as steel slag in soil stabilization can be an environment-friendly and cost-effective extraction technique to the disposal of solid waste materials. Previous studies investigated the bearing capacity and settlement of ground improved with granular columns with or without the geosynthetic encasement. However, very limited number of studies have investigated the response of ordinary stone columns without encasement and geosynthetic encased steel slag columns under lateral loading. In this paper, the lateral load capacity of steel slag granular column-soil composites has been investigated. For this purpose, a series of large direct shear tests were performed on the column-soil composites with the steel slag column and the ordinary stone column with or without the geosynthetic encasement. The effect of type of column materials (steel slag and sand), column diameter, number of columns, columns arrangement, and geosynthetic encasement on the shear strength parameters of column-soil composites have been studied. The experimental results show the effectiveness of using the steel slag columns to improve the lateral load-bearing performance of soil.

M K Gouda, Salah A Salman, Saad Ebied

β -titanium alloys are essential in many applications, particularly biomedical applications. Ti-14Mn β -type alloy was produced using an electric arc furnace from raw alloying elements in an inert atmosphere. The alloy was homogenized at 1000 °C for 8 h to ensure the complete composition distribution, followed by solution treatment at 900 °C, then quenched in ice water. The alloy was subjected to cold deformation via cold rolling with different ratios: 10, 30, and 90%. The phases change, microstructure, mechanical properties, and corrosion resistance of Ti-14Mn alloys were evaluated before and after cold rolling. The results showed that the β -phase is the only existed phase even after a high degree of deformation. The microstructure shows a combination of twinning and slipping deformation mechanisms in the deformed alloy. Microhardness values indicated a linear increase equal to 30% by increasing the ratio of cold deformation due to the strain hardening effect. The corrosion resistance of Ti-14Mn alloy was doubled after 90% cold rolling.

Daniel Hickox-Young, Danilo Puggioni, James M. Rondinelli

Over the past decade, materials that combine broken inversion symmetry with metallic conductivity have gone from a thought experiment to one of the fastest growing research topics. In 2013, the observation of the first uncontested polar transition in a metal, LiOsO$_3$, inspired a surge of theoretical and experimental work on the subject, uncovering a host of materials which combine properties previously thought to be contraindicated [Nat. Mater. \textbf{12}, 1024 (2013)]. As is often the case in a nascent field, the sudden rise in interest has been accompanied by diverse (and sometimes conflicting) terminology. Although ``ferroelectric-like" metals are well-defined in theory, i.e., materials that undergo a symmetry-lowering transition to a polar phase while exhibiting metallic electron transport, real materials find a myriad of ways to push the boundaries of this definition. Here, we review and explore the burgeoning polar metal frontier from the perspectives of theory, simulation, and experiment while introducing a unified taxonomy. The framework allows one to describe, identify, and classify polar metals; we also use it to discuss some of the fundamental tensions between theory and models of reality inherent in the terms ``ferroelectric" and ``metals.'' In addition, we highlight shortcomings of electrostatic doping simulations in modeling different subclasses of polar metals, noting how the assumptions of this approach depart from experiment. We include a survey of known materials that combine polar symmetry with metallic conductivity, classified according to the mechanisms used to harmonize those two orders and their resulting properties. We conclude by describing opportunities for the discovery of novel polar metals by utilizing our taxonomy.

Alexander A. Balandin, Fariborz Kargar, Tina T. Salguero et al.

The advent of graphene and other two-dimensional van der Waals materials, with their unique electrical, optical, and thermal properties, has resulted in tremendous progress for fundamental science. Recent developments suggest that taking one more step down in dimensionality - from monolayer, atomic sheets to individual atomic chains - can bring exciting prospects as the ultimate limit in material downscaling is reached while establishing an entirely new field of one-dimensional quantum materials. Here we review this emerging area of one-dimensional van der Waals quantum materials and anticipate its future directions. We focus on quantum effects associated with the charge-density-wave condensate, strongly-correlated phenomena, topological phases, and other unique physical characteristics, which are attainable specifically in van der Waals materials of lower dimensionality. Possibilities for engineering the properties of quasi-one-dimensional materials via compositional changes, vacancies, and defects, as well as the prospects of their applications in composites are also discussed.

Paola C. Torche, Andrea Silva, Denis Kramer et al.

We present a multi-scale computational framework suitable for designing solid lubricant interfaces fully in silico. The approach is based on stochastic thermodynamics founded on the classical thermally activated two-dimensional Prandtl-Tomlinson model, linked with First Principles methods to accurately capture the properties of real materials. It allows investigating the energy dissipation due to friction in materials as it arises directly from their electronic structure, and naturally accessing the time-scale range of a typical friction force microscopy. This opens new possibilities for designing a broad class of material surfaces with atomically tailored properties. We apply the multi-scale framework to a class of two-dimensional layered materials and reveal a delicate interplay between the topology of the energy landscape and dissipation that known static approaches based solely on the energy barriers fail to capture.