Material Parameters Research Articles

Explaining all-optical switching in ferrimagnets with heavy rare-earth elements by varying the spin-flip scattering probability of Gd in Co[formula omitted]Gd[formula omitted] alloys and Co/Gd bilayers

Using the microscopic three temperature model, we simulate single-pulse all-optical switching (AOS) in alloys and bilayers consisting of Co and Gd. In particular, we investigate its dependence on the spin-flip probability of Gd asf,Gd, a material parameter describing the strength of spin-phonon coupling. We do so to elucidate the mechanisms behind all-optical switching in systems where Co is coupled to heavy rare-earth elements with higher damping such as Tb. In alloys, our observations are twofold. First, an increase of asf,Gd leads to a broadening of the range of compositions for which AOS is observed. Second, the ideal Co content is decreased as asf,Gd is varied. For bilayers, our analysis indicates that switching is most efficient when asf,Gd takes on small values. Conversely, increasing the value of asf,Gd leads to a general suppression of AOS. Comparing alloys to bilayers, we find that AOS in alloys exhibits greater resilience to variations in asf,Gd than it does in bilayers.

Computational study of micropolar Eyrling-Powell ferrofluid flow

This study investigates the behavior of micropolar Eyring-Powell ferrofluids over a stretchable surface, considering heterogeneous-homogeneous chemical reactions, thermal radiation, and magnetic dipole effects. The governing partial differential equations are transformed into ordinary differential equations (ODEs) using similarity transformations, which are then solved using the shooting method with Runge-Kutta updates. The effects of various parameters on the flow and temperature fields are computed and visualized using MATLAB 2023. The results show that the velocity field decreases with increasing ferro-magnetic parameter β and fluid material parameter ß, while the temperature field increases with thermal radiation R, but decreases with higher dissipation parameter λ 1 and Prandtl number Pr. The results are in excellent agreement with previously published data, validating the accuracy of our approach.

Towards a quantitative understanding of bonding in supersonic single particle impacts: A three-dimensional FIB-SEM exploration

Particle bonding is crucial to coating quality in cold spray, but it has been a challenge to accurately quantify bonding even in single particle impacts. This paper uses FIB-SEM to explicitly map the particle-substrate interface for Cu-on-Cu single microparticle impacts in a full 3D rendering that spans a wide range of impact velocities. This approach permits a detailed quantification of the total bonding area and all of its associated components. In addition to revealing why prior 2D characterization efforts have missed important details about impact bonding, these data quantitatively reveal the evolution of bonding from its onset at the “critical velocity” Vcr (where bonding is generally poor, ∼6 %) to its peak at around 1.3‧Vcr (where almost 90 % of the particle bonds). Further increase in the velocity to 1.5‧Vcr and beyond finds the onset of hydrodynamic penetration and a decrease in bonding. These data then support the development of a simple analytical model based on oxide rarefication and extrusion of bare metal through gaps in the oxide layer as driving the development of bonding. The model reproduces the experiments and provides guidance on optimization of bonding as a function of material and process parameters.

Comparison of Mode I fracture toughness of an elastic and an elastoplastic methyl methacrylate polymer as measured by SENB and DCDC tests

An elastic and an elastoplastic methyl methacrylate polymer, both in the glassy state, have been submitted to mode I fracture characterization with two different tests, the single edge notch bending (SENB) and the double cleavage drilled compression (DCDC) tests. The elastic material toughness was simply assessed by the linear elastic fracture mechanics analysis. For the elastoplastic material, the J-integral was computed when the strain fields were available. Moreover, numerical analyses were carried out using finite element simulations with a phase-field damage approach, providing comparison when the J-integral had been calculated and estimate otherwise, of the critical energy release rate. For each material, as well as for each test, the values of the critical energy release rate that have been estimated here, are in good agreement with the literature. More interestingly, for the same material, both tests provide with very different estimates of this material parameter, leaving engineers uncertain on which test to choose to assess the material toughness in crack opening mode.

An implicit solution method for digital construction of temperature fields in concrete structures based on point temperature measurements

PurposeAt present, using the finite element method is difficult to efficiently and accurately construct the temperature field of mass concrete based on temperature measurement points. Thus, there is a need to propose a method for improvement.Design/methodology/approachThis study developed an implicit finite element method that digitally constructs the temperature field of mass concrete based on temperature measurement data. That is, in the proposed method of this paper, the temperature of the measuring point is also one of the boundary conditions, which real-time corrects the calculation error.FindingsIn this method, during the digital construction of the temperature field, the computed temperature approaches the actual measured value at the point of measurement with increasing iteration steps. Using this method and sufficient temperature measurement data, the errors in calculation conditions (such as the boundary conditions, the initial casting temperature and material parameters) can be automatically corrected during the iterative computation process.Originality/valueThis new method can improve calculation accuracy and allows the digitally constructed temperature field to converge to its true value with sufficient measurement data.

Evaluating the bonding effectiveness of CFRP patches in strengthening concrete structures

This study offers a thorough analysis of the efficiency of adhesively bonded Carbon Fiber-Reinforced Polymer (CFRP) patches in reinforcing concrete structures. In the dynamic field of civil engineering and infrastructure maintenance, utilizing modern materials and innovative techniques is crucial. Given the diverse stresses on concrete structures, sustainable reinforcement strategies like CFRP patching are vital. CFRP patches, with their high tensile strength and lightweight properties, reinforce concrete, enhancing its load-bearing capacity. The study reviews extensive literature on CFRP use, emphasizing its effectiveness in various environments. However, prevailing analyses often overlook shear-induced failures at the interface of bonded CFRP patches. To address this, the study introduces a novel fracture analytical technique, consolidating material parameters for assessing CFRP patch bonding efficiency. Experimental investigations compare epoxy, polyurethane, and silyl-modified polymers under mode-I loading conditions, revealing performance variations. The study underscores the importance of adhesive selection, advocating for a balance between strength and fracture energy absorption for optimal CFRP patch performance in concrete structures. It urges future design applications to consider these findings for enhanced selection and application of CFRP patches.

Electro-Mechanical Coupling Analysis of L-Shaped Three-Dimensional Braided Piezoelectric Composites Vibration Energy Harvester.

In this article, an L-shaped three-dimensional (3D) braided piezoelectric composite energy harvester (BPCEH) is established, which consists of an elastic layer composed of a 3D braided composite, flanked by upper and lower layers of piezoelectric material and two tuning mass blocks. Glass fiber and epoxy resin are used to produce a 3D braided composite. This L-shaped 3D BPCEH is mechanically designable and can be adapted to different work requirements by varying the braided angle of the 3D braided composite layer. The material parameters of 3D braided composites are predicted for different braided angles by means of a representative volume element (RVE). Electro-mechanical coupled vibration equations for the L-shaped 3D BPCEH are established. The impact of braided angles on voltage and power output is discussed in this article. Simulations using finite element method are conducted to analyze the voltage and power output responses at various braided angles. In addition, the effects of the mass of mass block B and the length of the beam on the output performance of the L-shaped 3D BPCEH are analyzed.

Enhancing Bovine Embryo Development In Vitro Using Oil-in-Water Nanoemulsions as Specific Carriers for Essential Lipids.

Worldwide meat consumption and production have nearly quintupled in the last 60 years. In this context, research and the application of new technologies related to animal reproduction have evolved in an accelerated way. The objective of the present study was to apply nanoemulsions (NEs) as carriers of lipids to feed bovine embryos in culture media and verify their impact on the development of embryos produced in vitro. The NEs were characterized by particle size, polydispersity, size distribution, physical stability, morphology using atomic force microscopy (AFM), surface tension, density, pH, and rheological behavior. The NEs were prepared by the emulsification/evaporation technique. A central composite rotatable design (CCRD) was used to optimize the NE fabrication parameters. The three optimized formulations used in the embryo application showed an emulsion stability index (ESI) between 0.046 and 0.086, which reflects high stability. The mean droplet diameter analyzed by laser diffraction was approximately 70-80 nm, suggesting a possible transit across the embryonic zona pellucida with pores of an average 90 nm in diameter. AFM images clearly confirm the morphology of spherical droplets with a mean droplet diameter of less than 100 nm. The optimized formulations added during the higher embryonic genome activation phase in bovine embryos enhanced early embryonic development.

Analytical solutions and material tailoring for combined radial expansion and twisting of functionally graded orthotropic hollow cylinders

Assuming that material properties are described by the same function of the radius, we first analytically find the displacement field in a functionally graded, orthotropic and linearly elastic hollow cylinder undergoing combined radial expansion and twisting. Subsequently, either for a desired axisymmetric displacement field or a stress distribution, we determine the required variations of the material properties to produce them in an inhomogeneous orthotropic cylinder. Numerical results presented for four example problems reveal the possibility of suitably varying material properties in the radial direction to simultaneously minimize the structural mass and the maximum circumferential stress on the inner surface of a hollow cylinder. It is found that out of the three heterogeneous cylinders of the same geometric and material parameters, the one having the least mass also has the smallest value of the maximum circumferential stress on the cylinder's inner surface. It occurs when the material moduli essentially vary affinely through the cylinder thickness. The analytical solutions presented here can serve as benchmarks for others to verify their numerical algorithms.

Tuning Textural Properties by Changing the Morphology of SBA-15 Mesoporous Materials.

Changing the morphology is an excellent option for altering the textural parameters of SBA-15 materials. This study provides a guide on how the properties of mesoporous structures behave according to their morphology and their contribution to thermal stability. The objective of this work was to synthesize different morphologies (spherical, hexagonal prisms, rice-like grains, rods, and fibers) of SBA-15 materials and evaluate the existing textural changes. The materials were synthesized by varying the temperature of the synthesis gel from 25 °C to 55 °C, with stirring at 300 or 500 rpm. The results of X-ray diffraction, Fourier transform infrared spectroscopy, N2 adsorption and desorption, and scanning electron microscopy were evaluated. Thermal stability tests were also conducted in an inert atmosphere. The materials were successfully synthesized, and it was observed that they all exhibited different characteristics, such as their ordering, interplanar distance, mesoporous parameter, specific surface area, micropore and mesopore volumes, external mesoporous area, and wall thickness. They also presented different thermal stabilities. The rice grain morphology had the highest specific surface area (908.8 cm2/g) and the best thermal stability, while the rod morphology had the best pore diameter (7.7 nm) and microporous volume (0.078 cm3/g).

Effect of cotton‐polyester composite yarn on the physico‐mechanical and comfort properties of woven fabric

AbstractCotton is the most widely used natural cellulosic polymer and polyester is a synthetic polymer. The use of polyester fiber is increasing gradually day by day due to its strength and longevity, while the use of cotton fiber is decreasing due to its unavailability. At present, the use of cotton‐polyester composites is ubiquitous. This research work aims to assess the physical, mechanical and comfort properties of the woven fabric using cotton‐polyester composite yarns in a weft direction and coarser yarn count because of the use of these fabrics in the future for the denim manufacturing process. Four different samples were fabricated by using 100% cotton (10 Ne) yarn in the warp direction and 100% cotton, cotton‐polyester composite, and 100% polyester yarn in the weft direction of the fabric. Similar fabric and machine parameters were maintained for manufacturing all the samples. The samples were then tested for areal density, tensile strength, thickness, abrasion resistance and pilling, drape, flexural rigidity, and air permeability to find the optimum capability of the fabric. Physico‐mechanical properties with the proportion of increasing polyester components in fabrics improves areal density (184 to 199 g/m2), strength (almost 19 times in weft direction), drape (0.655% to 0.789%), and flexural rigidity (almost double). On the other hand, increasing comfortability properties with the proportion of cotton components in fabrics improve air permeability (139.85 to 159.58 cc/s/cm2), abrasion (only 3.036% mass loss), and pilling resistance (grading 4 after 2000 cycles).Highlights Composite yarns made of cotton and polyester provide a method of improving fabric properties for better performance. Higher proportions of cotton make clothes more breathable and less likely to pill and wear out. Polyester parts make fabrics stronger, more durable, and less likely to wear out. Cotton‐polyester composites are ideal and have potential for various textile applications. Blending natural and synthetic fibers composite allows for customized fabrics that meet specific performance needs without compromising comfort.

Properties of Nb x Ti(1−x)N thin films deposited on 300 mm silicon wafers for upscaling superconducting digital circuits

Scaling superconducting digital circuits requires fundamental changes in the current material set and fabrication process. The transition to 300 mm wafers and the implementation of advanced lithography are instrumental in facilitating mature CMOS processes, ensuring uniformity, and optimizing the yield. This study explores the properties of Nb x Ti(1−x)N films fabricated by magnetron DC sputtering on 300 mm Si wafers. As a promising alternative to traditional Nb in device manufacturing, Nb x Ti(1−x)N offers numerous advantages, including enhanced stability and scalability to smaller dimensions, in both processing and design. As a ternary material, Nb x Ti(1−x)N allows engineering material parameters by changing deposition conditions. The engineered properties can be used to modulate device parameters through the stack and mitigate failure modes. We report characterization of Nb x Ti(1−x)N films at less than 2% thickness variability, 2.4% T c variability and 3% composition variability. Film resistivity (140–375 Ωcm) shows a strong correlation with the film oxygen content, while the critical temperature T c (4.6 K–14.1 K) is strongly affected by film stoichiometry and its microstructure has only a moderate effect on modifying T c. Our results offer insights about the interplay between film stoichiometry, film microstructure and critical temperature.

Study on the Effect of Cracking Parameters on the Migration Characteristics of Chloride Ions in Cracked Concrete

In engineering, concrete often develops cracks due to various reasons, which accelerate the erosion rate of chloride ions in concrete and consequently expedite the degradation of the mechanical properties of concrete structures. This study simplifies the four-phase model into a two-phase model using homogenization methods. Based on this, numerical simulations are employed to investigate the influences of dimensionless structural parameters and material parameters of cracks on the equivalent diffusion coefficient of cracked concrete, and a theoretical model for the equivalent diffusion coefficient of cracked concrete is established according to Fick’s diffusion law. The research findings indicate that when cracks are positioned in the middle of the boundary through which chloride ions enter and exit the concrete, and the direction of the cracks is parallel to the diffusion direction of chloride ions; this scenario is the most detrimental to the durability of concrete. For n cracks (n ≥ 2), when they are parallel to the x-axis and symmetrical about the x-axis, and the spacing between cracks equals 1/n times the width of the concrete, this scenario is the most detrimental to the durability of concrete containing multiple cracks. Whether for a single crack or multiple cracks, when they are in the most unfavorable condition, the “parallel-then-series” theoretical model can accurately predict the equivalent diffusion coefficient of cracked concrete.

Study on Structure-Borne Noise Characteristics of Long-Span Steel Truss Bridge in Urban Rail Transit

The application of long-span steel bridge in urban rail transit is becoming more and more extensive, but the structure-borne noise of steel bridge induced by passing train is also prominent. Research on the structure-borne noise problem of long-span steel bridge in urban rail transit has positive significance in promoting the sustainable development of steel bridge, and improving the quality of sound environment along rail transit. In this work, dynamic receptance principle, finite element method and statistical energy method are combined to establish the structure-borne noise prediction model of the long-span steel bridge, and the rationality and validity of the model are verified based on field measurement results. Based on the prediction model, the noise radiation characteristics of large-span steel truss bridge in urban rail transit are studied, and the following conclusions are drawn: The bridge deck has the strongest acoustic contribution ability, with the contribution rate of 33–44%, followed by the longitudinal web and transverse web, with the contribution rate of 23–30%, followed by the truss chord, with the contribution rate of 5–8%, and the truss web, longitudinal wing and transverse wing have weak contribution ability, with the contribution rate of less than 2%. The acoustic radiation efficiency of steel truss bridge components reaches its peak at the critical frequency, and the critical frequency is determined by the thickness of steel bridge plate components when the material parameters are fixed. Under ordinary track structures, the middle-to-high frequency noise distribution characteristics of large-span steel truss bridge structure are obvious. Damping pad floating slab track can effectively suppress the high-frequency noise of steel bridge, and the overall sound level can be reduced by about 11–14[Formula: see text]dB.

Modeling and measurement of dielectric anisotropy in materials manufactured via fused filament fabrication processes

Additive manufacturing (AM) is increasingly recognized as an enabling technology for novel devices with increased functionality and bandwidth for microwave applications. However, due to the layer-by-layer build approach employed by most AM techniques, internal patterns are introduced to printed materials, which cause an effective anisotropy in their material parameters. An electrostatic model inspired by parallel plate capacitors, describing the dielectric anisotropy of materials manufactured with fused filament fabrication (FFF) AM techniques is proposed in this work. The accuracy of the model’s predictions about the permittivity tensor of printed materials is investigated via numerical simulations. Furthermore, permittivity tensor measurements are carried out for samples printed with various materials and print settings. Measurement data is fitted to the model via a least squares approach, and excellent agreement is observed. Novel conclusions about the impact of material and print parameters on the effective permittivity of additively manufactured materials, improving the accuracy in modeling and designing additively manufactured microwave devices are drawn.

Assessing the behavior of a hybrid model of the knee with contact surrogate under parameter uncertainties

Modeling the knee is an important factor in increasing the quality of life of both healthy individuals and patients. Nevertheless, the intricate nature of the knee makes this problem complicated. In this study, an extension to an established planar knee joint model with Hertzian contact pairs is proposed with contact mechanics based on polynomial chaos expansion surrogate. Firstly, the finite element (FE) model is made representing a contact pair of sphere-to-plane type with two layers on both bodies, corresponding to the cartilage and the bone. Five variables corresponding to both geometry and material parameters are used to parametrize this model. Then, 128 distinct variants of the FE model are created based on a quasi-Monte Carlo sequence. This dataset is used to train and validate the surrogate. The trained surrogate is proven to have predictive capabilities with an average nRMSE of 0.2% in randomized test/train splits. When included in a model of the knee and tested under parameter uncertainties in Monte Carlo simulations, it results in nRMSE of 58% for angular coordinate compared to the original model with Hertzian pair. This signifies the high influence of contact formulation on the model output and the need for more physically based models in knee contact modeling.

Versatile Landscape of Low-k Polyimide: Theories, Synthesis, Synergistic Properties, and Industrial Integration.

The development of microelectronics and large-scale intelligence nowadays promotes the integration, miniaturization, and multifunctionality of electronic and devices but also leads to the increment of signal transmission delays, crosstalk, and energy consumption. The exploitation of materials with low permittivity (low-k) is crucial for realizing innovations in microelectronics. However, due to the high permittivity of conventional interlayer dielectric material (k ∼ 4.0), it is difficult to meet the demands of current microelectronic technology development (k < 3.0). Organic dielectric materials have attracted much attention because of their relatively low permittivity owing to their low material density and low single bond polarization. Polyimide (PI) exhibits better application potential based on its well permittivity tunability (k = 1.1-3.2), high thermal stability (>500 °C), and mechanical property (modulus of elasticity up to 3.0-4.0 GPa). In this review, based on the synergistic relationship of dielectric parameters of materials, the development of nearly 20 years on low-k PI is thoroughly summarized. Moreover, process strategies for modifying low-k PI at the molecular level, multiphase recombination, and interface engineering are discussed exhaustively. The industrial application, technological challenges, and future development of low-k PI are also analyzed, which will provide meaningful guidance for the design and practical application of multifunctional low-k materials.

Advanced sulfonated polyester nanofiltration membranes for superior dye separation, desalination, and chlorine resistance

This study introduces an innovative thin-film composite (TFC) nanofiltration membrane made from sulfonated polyvinyl alcohol (SPVA)-based polyester, specifically engineered for effective wastewater treatment. This novel membrane is developed through interfacial polymerization on a polysulfone substrate, demonstrating exceptional water permeability and filtration efficiency. It is particularly effective in separating dyes and salts due to its superior hydrophilicity, optimized surface charge, and precisely tailored morphology. Critical fabrication parameters were finely tuned, utilizing a 2 wt% SPVA solution and a 0.35 wt% trimesoyl chloride (TMC) in the organic phase, with both immersion and polymerization times set at 2 min. The performance metrics are outstanding, featuring a water permeance of 97 L m−2 h−1·bar−1, high dye rejection rates (99.51 % for Congo Red and 99.55 % for Brilliant Blue), and significant salt permeability (30.35 % for Na2SO4 and 29.93 % for MgSO4). The membrane also exhibits excellent antifouling properties, robust chlorine resistance (up to 48,000 ppm h), and sustained operational stability, underscoring its industrial viability for dye and textile effluent treatment. The TFC-SPVA membrane addresses critical environmental challenges in wastewater management, marking a significant advancement in membrane technology.

Effect of variability of mechanical properties on the predictive capabilities of vulnerable coronary plaques

Background and Objective:Coronary plaque rupture is a precipitating event responsible for two thirds of myocardial infarctions. Currently, the risk of plaque rupture is computed based on demographic, clinical, and image-based adverse features. However, using these features the absolute event rate per single higher-risk lesion remains low. This work studies the power of a novel framework based on biomechanical markers accounting for material uncertainty to stratify vulnerable and non-vulnerable coronary plaques. Methods:Virtual histology intravascular ultrasounds from 55 patients, 29 affected by acute coronary syndrome and 26 affected by stable angina pectoris, were included in this study. Two-dimensional vessel cross-sections for finite element modeling (10 sections per plaque) incorporating plaque structure (medial tissue, loose matrix, lipid core and calcification) were reconstructed. A Montecarlo finite element analysis was performed on each section to account for material variability on three biomechanical markers: peak plaque structural stress at diastolic and systolic pressure, and peak plaque stress difference between systolic and diastolic pressures, together with the luminal pressure. Machine learning decision tree classifiers were trained on 75% of the dataset and tested on the remaining 25% with a combination of feature selection techniques. Performance against classification trees based on geometric markers (i.e., luminal, external elastic membrane and plaque areas) was also performed. Results:Our results indicate that the plaque structural stress outperforms the classification capacity of the combined geometric markers only (0.82 vs 0.51 area under curve) when accounting for uncertainty in material parameters. Furthermore, the results suggest that the combination of the peak plaque structural stress at diastolic and systolic pressures with the maximum plaque structural stress difference between systolic and diastolic pressures together with the systolic pressure and the diastolic to systolic pressure gradient is a robust classifier for coronary plaques when the intrinsic variability in material parameters is considered (area under curve equal to [0.91–0.93]). Conclusion:In summary, our results emphasize that peak plaque structural stress in combination with the patient’s luminal pressure is a potential classifier of plaque vulnerability as it independently considers stress in all directions and incorporates total geometric and compositional features of atherosclerotic plaques.

Computational study of transcatheter aortic valve replacement based on patient-specific models-rapid surgical planning for self-expanding valves.

Transcatheter aortic valve replacement (TAVR) is a minimally invasive interventional solution for treating aortic stenosis. The complex post-TAVR complications are associated with the type of valve implanted and the position of the implantation. The study aimed to establish a rapid numerical research method for TAVR to assess the performance differences of self-expanding valves released at various positions. It also aimed to calculate the risks of postoperative paravalvular leak and atrioventricular conduction block, comparing these risks to clinical outcomes to verify the method's effectiveness and accuracy. Based on medical images, six cases were established, including the aortic wall, native valve and calcification; one with a bicuspid aortic valve and five with tricuspid aortic valves. The parameters for the stent materials used by the patients were customized. High strain in the contact area between the stent and the valve annulus may lead to atrioventricular conduction block. Postoperatively, the self-expanding valve maintained a circular cross-section, reducing the risk of paravalvular leak and demonstrating favorable hemodynamic characteristics, consistent with clinical observations. The outcomes of the six simulations showed no significant difference in valve frame morphology or paravalvular leak risk compared to clinical results, thereby validating the numerical simulation process proposed for quickly selecting valve models and optimal release positions, aiding in TAVR preoperative planning based on patients'geometric characteristics.