Search Results (152)

Particle-reinforced aluminum matrix composites demonstrate remarkable potential for use in aerospace, precision instruments, and electronic packaging applications due to their superior specific strength, high specific stiffness, and low thermal expansion coefficient. However, increasing the reinforcement volume fraction to enhance the elastic modulus often leads to a reduction in plasticity and machining performance. This study investigates hot-pressed 27 vol.% TiB₂/2024, 15 vol.% diamond/2024, and 37 vol.% SiC/2024 composite with equivalent elastic moduli, focusing on the effects of TiB₂ particle size and T6 heat treatment on their microstructure, mechanical properties, and machining performance. The results reveal that increasing the TiB₂ particle size from 7 μm to 25 μm reduces the tensile strength from 397.1 MPa to 371.7 MPa, increases surface roughness values from 110 nm to 177 nm, but simultaneously decreases tool wear. Among the tested composites, the 27 vol.% TiB₂/2024 composite exhibits optimal interfacial bonding without Al₄C₃ formation, providing the most effective load-bearing strengthening, as well as the lowest surface roughness and minimal tool wear. Moreover, the T6 heat treatment further enhanced the tensile strength of the 27 vol.% TiB₂/2024 composite from 397.1 MPa to 421.7 MPa, while reducing the surface roughness values during turning from 110 nm to 79 nm and further minimizing tool wear, thus achieving outstanding overall mechanical and machining performance. Full article

This study investigates the elastic properties of bio-epoxy composites reinforced with natural fibres (flax, hemp) and synthetic fibres (S-glass), with particular focus on the effect of the fibre volume fraction (VF) ranging from 10% to 70%. Three-dimensional representative volume element (RVE) models were developed for single-fibre, hybrid, and multi-fibre systems. The mean-field homogenisation (MF) approach, based on the Mori–Tanaka scheme, and finite element analysis (FEA) with periodic boundary conditions were employed to predict the effective elastic properties, including longitudinal, transverse, and shear moduli, as well as Poisson’s ratio. These numerical predictions were validated against analytical models, including the rule of mixtures, Chamis, and composite cylinder assemblage (CCA) methods. The results demonstrate that increasing the VF enhances longitudinal, transverse, and shear moduli while reducing Poisson’s ratio in natural fibre composites. The good agreement between numerical, semi-analytical, and analytical methods validates the 3D RVE models as useful tools for predicting the properties of multi-hybrid natural fibre composites, supporting their design for lightweight structural applications. Full article

Natural fiber-reinforced unidirectional composites are increasingly adopted in modern industries due to their superior mechanical performance and desirable properties from both material and engineering perspectives. Among various approaches, representative volume element (RVE) generation and analysis is considered one of the most suitable and convenient methods for predicting the elastic moduli of composites. The main aim of this study is to investigate and compare the elastic moduli of natural fiber–reinforced unidirectional composite RVEs using theoretical, numerical, and machine learning models. The numerical predictions in this study were generated using the ANSYS Material Designer tool (version ANSYS 19). A comparison was made between experimental results reported in the literature and different theoretical models, showing high accuracy in validating these numerical outcomes. A dataset comprising 1600 samples was generated from numerical models in combination with the well-known theory of RVE, namely rule of mixture (ROM), to train and test two machine learning algorithms: Random Forest and Linear Regression, with the goal of predicting three major elastic moduli—longitudinal Young’s modulus (E₁₁), in-plane shear modulus (G₁₂), and major Poisson’s ratio (V₁₂). To evaluate model performance, mean squared error (MSE), mean absolute error (MAE), mean absolute percentage error (MAPE), and coefficient of determination (R²) were calculated and compared against datasets with and without the theoretical values as input variables. The performance metrics revealed that with the theoretical values, both Linear Regression and Random Forest predict E₁₁, G₁₂, and V₁₂ well, with a maximum MSE of 0.033 for G₁₂ and an R² score of 0.99 for all cases, suggesting they can predict the mechanical properties with excellent accuracy. However, the Linear Regression model performs poorly when theoretical values are not included in the dataset, while Random Forest is consistent in accuracy with and without theoretical values. Full article

New compostable materials have been developed to replace single-use soft materials such as polyurethane foams (PUR). To this end, eco-friendly systems have been formulated on the basis of agar gels prepared in mixed solvent (glycerol/water) to meet specifications, i.e., stiffness of several hundred kPa, reasonable extensibility, and good stability when exposed to open air. While the addition of glycerol slows down gelation kinetics, mechanical properties are improved up to a glycerol content of 80 wt%, with enhanced extensibility of the gels while maintaining high Young’s moduli. Swelling analyses of mixed gels, in water or pure glycerol, demonstrate the preservation of an energetic network, with no change in volume, in pure water and the transition towards an entropic network in glycerol related to the partial dissociation of helix bundles. Dimensional and mechanical analysis of gels aged in an open atmosphere at room temperature shows that the hygroscopic character of glycerol enables sufficient water retention to maintain the physical network, with antagonistic effects linked to relative increases in glycerol, which tends to weaken the network, and agar, which on the contrary strengthens it. Complementary analyses carried out on aged agar gels formulated with an initial glycerol/water mass composition of 60/40, the most suitable for the targeted development, enabled the comparison of the properties of agar gels favorably with those of PURs and verified their stability during long-term storage, as well as their non-toxicity and compostability. Full article

In Hungary, on-site mixed stabilization of cohesive soil is considered only as soil improvement not a proper pavement layer, therefore its bearing capacity is not taken into account when designing pavement. It was our hypothesis that on low-volume roads built on cohesive soil, lime or lime–cement stabilization can be an alternative to granular base layers. A case study was conducted to obtain initial results and to verify the research methodology. The efficacy of lime stabilization was evaluated across eight experimental road sections, with a view of assessing its structural and economic performance in comparison with crushed stone base layers reinforced with geo-synthetics. The results of the testing demonstrated elastic moduli of 120–180 MPa for the lime-stabilized layers, which closely matched the 200–280 MPa range observed for the crushed stone bases. The results demonstrated that lime stabilization offers a comparable load-bearing capacity while being the most cost-effective solution. Furthermore, this approach enhances sustainability by enabling the utilization of local soils, reducing reliance on imported materials, minimizing transport-related costs, and lowering carbon emissions. Lime stabilization provides a durable, environmentally friendly alternative for road construction, effectively addressing the challenges of material scarcity and rising construction costs while supporting infrastructure resilience. The findings highlight its potential to replace traditional base layers without compromising structural performance or economic viability. Full article

We report a systematic investigation on the physicochemical properties of polymer systems consisting of polyvinyl alcohol (PVA) and hyaluronic acid (HA) mixed in various volume ratios (1/4, 2/3, 1/1, 3/2, and 4/1). At PVA/HA ratios above 1/1, in the presence of glutaraldehyde and divinyl sulfone as crosslinking agents, hydrogels are formed. Their swelling behavior is dependent on the polymer ratio, with the highest water uptake determined for PVA/HA 4/1. The in situ generation of reactive oxygen species (HO^• radicals) under UV-A irradiation, in the presence of riboflavin as a photoinitiator, is evidenced by electron paramagnetic resonance (EPR) spectroscopy. The diffusion of small paramagnetic molecules across the interface of two PVA/HA 4/1 gel pieces placed in direct contact reveals the occurrence of molecular exchange, which could indicate some degree of self-repair of the hydrogel network. When the paramagnetic moiety is attached to the HA polymer by spin labeling, the absence of diffusion demonstrates the stability of the crosslinked HA chains within the PVA/HA network. The structural modifications induced by crosslinking, by the presence of riboflavin, and by exposure to UV-A light, and the resulting alterations in the mechanical behavior of the hydrogels are monitored by infrared spectroscopy and rheology. Only a slight decrease in the viscoelastic moduli values is noted, indicating that the formation of HO^• radicals has minimal impact on the macroscopic properties of the hydrogels. Full article

Background: Three-dimensional (3-D) printing paired with tissue-engineering strategies promises to overcome the volume, contour, and donor-site limitations of traditional breast reconstruction. Patient-specific, bioabsorbable constructs could enable one-stage procedures that better restore aesthetics and sensation. Methods: A narrative review was conducted following a targeted PubMed search (inception—April 2025) using combinations of “breast reconstruction,” “tissue engineering,” “3-D printing,” and “scaffold.” Pre-clinical and clinical studies describing polymer-based chambers or scaffolds for breast mound or nipple regeneration were eligible. Data was extracted on scaffold composition, animal/human model, follow-up, and volumetric or histological outcomes. Results: Forty-three publications met inclusion criteria: 35 pre-clinical, six early-phase clinical, and two device reports. The predominant strategy (68% of studies) combined a vascularized fat flap with a custom 3-D-printed chamber to guide adipose expansion. Poly-lactic acid, poly-glyceric acid, poly-lactic-co-glycolic acid, poly-4-hydroxybutyrate, polycarbonate, and polycaprolactone were the principal polymers investigated; only poly-4-hydroxybutyrate and poly-lactic acid have been tested for nipple scaffolds. Bioabsorbable devices supported up to 140% volume gain in large-animal models, but even the best human series (≤18 months) achieved sub-mastectomy volumes and reported high seroma rates. Mechanical testing showed elastic moduli (5–80 MPa) compatible with native breast tissue, yet long-term load-bearing data are scarce. Conclusions: Current evidence demonstrates biocompatibility and incremental adipose regeneration, but clinical translation is constrained by small sample sizes, incomplete resorption profiles, and regulatory uncertainty. Standardized large-animal protocols, head-to-head polymer comparisons, and early human feasibility trials with validated outcome measures are essential next steps. Nevertheless, the convergence of 3-D printing and tissue engineering represents a paradigm shift that could ultimately enable bespoke, single-stage breast reconstruction with superior aesthetic and functional outcomes. Full article

Due to the potential to integrate structural load bearing and energy storage within one single composite structural component, the development of carbon fiber (CF)-based structural power composites (SPCs) has garnered significant attention in electric aircraft, electric vehicles, etc. Building upon our previous investigation of the electrochemical performance of SPCs, this work focuses on elastic–plastic behaviors of the bicontinuous structural electrolyte matrices (BSEMs) and carbon fiber composite electrodes (CFCEs) in SPCs. Representative volume element (RVE) models of the BSEMs were numerically generated based on the Cahn–Hilliard equation. Furthermore, RVE models of the CFCEs were established, consisting of the BSEM and randomly distributed CFs. The moduli of BSEMs and the transverse moduli of CFCEs with different functional pore phase volume fractions were predicted and validated against experimental results. Additionally, the local plasticity of BSEMs and CFCEs in the tensile process was analyzed. The work indicates that the presence of the bicontinuous structure prolongs the plasticity evolution process, compared with the traditional polymer matrix, which could be used to explain the brittle-ductile transition observed in the matrix-dominated load-bearing process of CFCEs in the previous literature. This work is a step forward in the comprehensive interpretation of the elastic–plastic behaviors of bicontinuous matrices and multifunctional SPCs for realistic engineering applications. Full article

In this work, we develop a method for homogenizing effective second-order gradient continuum models for 2D periodic composite materials. A constitutive law is formulated using a variational approach combined with the Hill macro-homogeneity condition for strain energy. Incorporating strain gradient effects enhances the constitutive law by linking the hyperstress tensor to the second-order gradient of displacement, capturing elastic size and microstructure effects beyond classical Cauchy elasticity. The effective strain gradient moduli are calculated for composites exhibiting strong internal length effects, validating the proposed approach by computing the strain energy at different scales. Additionally, we develop an inverse homogenization method to compute local mechanical properties (properties of the constituents) given known global properties (effective properties), showing good agreement with the literature data. This framework is extended to study wave propagation by analyzing longitudinal and shear waves in 2D composite materials. The effects of inclusion shape and volume percentage on wave propagation are examined, revealing that elliptic inclusions lead to a slight increase in both modes of propagation. Finally, we investigate the impact of property contrast between the inclusion and matrix, demonstrating its influence on wave dispersion. Full article

Organic matter plays a vital role in shale reservoirs as both a hydrocarbon storage medium and migration pathway. However, the quantitative relationship between the microstructural features of organic matter and the macroscopic mechanical and failure behaviors of shale remains unclear due to rock heterogeneity and opacity. In this study, high-resolution three-dimensional digital core models of shale were reconstructed using Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) imaging. The digital models captured the spatial distribution of silicate minerals, clay minerals, and organic matter. Numerical simulations of uniaxial tensile failure were performed on these models, considering variations in the organic matter volume fraction and fractal dimension. The results indicate that an increased organic matter volume fraction and fractal dimension are associated with lower tensile strength, simpler fracture geometry, and reduced acoustic emission activity. Tensile cracks preferentially initiate at interfaces between minerals with contrasting elastic moduli, especially between organic matter and clay, and then propagate and coalesce under loading. These findings reveal that both the volume fraction and fractal structure of organic matter are reliable predictors of tensile strength and damage evolution in shale. This study provides new microscale insights into shale failure mechanisms and offers guidance for optimizing hydraulic fracturing in organic-rich formations. Full article

Concrete is a highly heterogeneous composite material, and accurately predicting its elastic modulus remains a major challenge in mechanical analysis. To address this, this study systematically investigates the predictive performance of several classical homogenization methods for estimating the effective elastic modulus of concrete, including the dilute approximation, self-consistent method, generalized self-consistent method, Mori–Tanaka model, differential method, as well as the Voigt and Reuss models. To enhance prediction accuracy, an improved computational framework is proposed based on an iterative strategy that enables dynamic updating of model parameters. This approach combines principles of mesomechanics with numerical simulation techniques and is implemented using Mathematica for both symbolic and numerical computations. The performance of the models is evaluated under varying aggregate volume fractions and aggregate-matrix stiffness combinations, and validated using multiple experimental datasets from the literature. The results show that the iterative strategy significantly improves the predictive accuracy of several models, reducing the maximum error by up to 30%. Further analysis indicates that the dilute method performs best at low aggregate volume fractions, the Mori–Tanaka model yields the most accurate results when the aggregates are stiff and moderately concentrated, and the generalized self-consistent method outperforms the standard version when the elastic moduli of the aggregate and matrix are similar. Full article

The success of orthopedic implants critically depends on achieving mechanical and biological compatibility with bone tissue. Traditional titanium implants often suffer from high stiffness, which induces stress shielding, a phenomenon that compromises implant integration and accelerates prosthetic loosening. This study introduces an innovative approach to mitigate these limitations by engineering a porous titanium substrate with a controlled microstructure. Utilizing sodium chloride as a spacer holder, an elution and sintering process was applied at 1250 °C under high vacuum conditions to reduce the material’s elastic modulus. By manipulating NaCl volume fractions (20%, 25%, 30%, and 35%), porous titanium samples were created with elastic moduli between 16.37 and 22.56 GPa, closely matching cortical bone properties (4 to 20 GPa). A hydroxyapatite coating applied via plasma thermal spraying further enhanced osseointegration of the material. Comprehensive characterization through X-ray diffraction, scanning electron microscopy, and compression testing validated the material’s structural integrity. In vitro cytotoxicity assessments using osteoblast cells demonstrated exceptional cell viability exceeding 70%, confirming the material’s biocompatibility. These findings represent a significant advancement in biomaterial design, offering a promising strategy for developing next-generation joint prostheses with superior mechanical and biological adaptation to bone tissue. Full article

Woven composites and natural fiber-reinforced composites both have widespread applications in various industries due to their appealing load-carrying capacity and performance compared to conventionally manufactured composites, such as polymeric composites. Representative volume element (RVE) generation is one of the most effective and widely adopted methods for estimating mechanical performance in current research. This study aims to explore the effects of three significant factors in woven composite RVEs: yarn spacing (from 0.5 mm to 1.5 mm), fabric thickness (from 0.2 to 0.5 mm), and shear angle (from 3.5 to 15 degrees) through finite element methods and statistical analysis to understand their effectiveness in the elastic moduli’s. The validation of this research has been conducted using available literature. The generation of representative volume elements (RVEs) and the calculation of elastic moduli were performed using ANSYS-19, including the material designer feature. The experimental design was carried out using Design-Expert software version 13, which used response surface methodology. The materials selected for this study were jute fiber and epoxy. After obtaining the elastic moduli from the ANSYS material designer, three responses were considered: longitudinal Young’s modulus (E₁₁), in-plane shear modulus (G₁₂), and major Poisson’s ratio (V₁₂). ANOVA (Analysis of Variance) and 3D contour graphs were generated to further analyze and correlate the effects of the selected materials on these responses. These investigations revealed that in comparison to twill structure, plain structure in natural fiber-reinforced woven composites could be a good alternative. Additionally, the findings highlighted that yarn spacing and fabric thickness significantly influence the considered moduli in plain-weave NFRC material RVEs. However, in twill-woven composite RVEs, the effects of yarn spacing, fabric thickness, and shear angle were found to be considerable. Moreover, statistical analysis has found the best combinations for both plain and twill structures, while the yarn spacing was 1 mm, the shear angle was 9.25 degrees, and the fabric thickness was 0.35 mm. Full article

Elastic moduli are important mechanical properties that describe a material’s stiffness and its deformation under elastic loading. In addition to experimental techniques, computational homogenization is commonly used for composite materials to calculate their elastic moduli. This research employs a deep learning algorithm, specifically a Feedforward Neural Network (FNN), to predict the longitudinal and transverse Young’s modulus, shear modulus, and Poisson’s ratio of various unidirectional (UD) composites. The predictions are based on several features, including the names of the composites, Young’s moduli and Poisson’s ratios of the fibers and matrices, and the fiber volume fraction. Initially, 20 different UD composites were selected from the existing literature. ANSYS-19 Material Designer was then utilized to calculate the elastic moduli of these materials while varying the fiber volume fraction from 0.2 to 0.7. This process generated a dataset of 1948 samples, with 80% of the data allocated for training the FNN model and the remaining 20% used to evaluate performance metrics of the test data. These metrics include mean squared error (MSE), root mean squared error (RMSE), mean absolute error (MAE), and R² score. The results indicate that, with optimized hyperparameters, the FNN model can accurately predict the elastic moduli, demonstrating its effectiveness as a tool for calculating the elastic properties of UD composites. Full article

This research explores the physical properties of refractory high-entropy alloys Ti₃Zr_yNbV_x (0.5 ≤ x ≤ 3.5; 1 ≤ y ≤ 2), utilizing the first-principles exact muffin-tin orbitals method, in addition to the coherent potential approximation. We examine the atomic size difference (δ), the valence electron concentration (VEC) and the total energy of the body-centered cubic (bcc), the face-centered cubic (fcc) and the hexagonal close-packed (hcp) lattices, revealing a disordered solid solution with a bcc lattice as the stable phase of these alloys. The stability of the bcc Ti₃Zr_yNbV_x alloys increases with the addition of vanadium, and slightly decreases with increasing Zr concentration. All the investigated RHEAs have densities less than 6.2 g/cm³. Adding V to the Ti-Zr-Nb-V system reduces the volume and slightly enhances the density of the studied alloys. Our results show that increasing V content increases the tetragonal shear modulus C′, which assures that V enhances the mechanical stability of the bcc phase, and also increases the elastic moduli. Moreover, all the examined alloys are ductile. Vickers hardness and bond strength increase as V concentration increases. In contrast, decreasing Zr content reduces the density and increases the hardness and the bond strength of the present RHEAs, potentially resulting in systems with desirable mechanical properties and lower densities. These findings provide theoretical insights into the behavior of RHEAs, and emphasize the necessity for additional experimental investigations. Full article