Search Results (953)

With the expanding electric vehicle market, there is increasing demand for improved battery safety and fast-charging performance. Ceramic-based solid electrolytes have attracted attention due to their high thermal and electrochemical stabilities. Li-glass solid electrolytes (e.g., Li₂O–LiCl–B₂O₃–Al₂O₃, LCBA) are promising materials because they enable low-temperature sintering (<550 °C), suppress lithium volatilization, mitigate ionic conductivity degradation, and enable cost-effective manufacturing. LCBA can be co-sintered with graphite anodes to form composite anode materials for LCBA-based all-solid-state batteries. However, insufficient densification and shrinkage mismatch often lead to limited ionic conductivity and interfacial delamination. In this study, the sintering behavior of LCBA was investigated using a hot-press-assisted process, and LCBA/graphite composite anodes were co-sintered to evaluate their electrochemical and interfacial properties. The LCBA electrolyte sintered at 550 °C exhibited high densification and an ionic conductivity of 3.86 × 10⁻⁵ S cm⁻¹. Additionally, the composite containing 50 wt% LCBA achieved a maximum tensile stress of ~0.23 MPa and a high interfacial fracture energy of ~180–200 J m⁻², indicating enhanced deformation tolerance and fracture resistance. This approach improves the densification, ionic conductivity, and interfacial mechanical stability of LCBA solid electrolytes and their composite anodes, highlighting their potential for next-generation all-solid-state secondary battery applications. Full article

A deep understanding of hydrogen diffusion in metals under stress is crucial for revealing the mechanism of hydrogen embrittlement. While the effects of isotropic and uniaxial stress have been studied, the atomic-scale mechanism under a pure biaxial stress state remains unclear. This work employs molecular dynamics simulations to investigate hydrogen diffusion in α-iron under controlled biaxial stress. The results show that biaxial stress influences diffusion indirectly by altering the lattice geometry and thus the migration energy barrier. It is found that the diffusion path is governed by the direction of the minimum principal strain, while the diffusion rate is controlled by the maximum tensile principal strain, with which it exhibits an approximately exponential relationship. These insights clarify the distinct roles of different strain components, providing a refined framework for understanding hydrogen behavior under complex stress states and guiding the design of hydrogen-resistant materials. Full article

To address the depletion of shallow coal resources, mining activities have progressed to greater depths, where rock masses contain numerous fractures due to complex geological conditions, making grouting reinforcement essential for ensuring stability. Using digital image correlation, this study investigated the strain evolution characteristics of grouted fractured specimens of three rock types—mudstone, coal–rock, and sandstone—under uniaxial compression. Analysis of the strain evolution process focused on two typical fracture inclinations of 0° and 60°, while examination of the peak strain characteristics covered five inclinations, namely 0°, 15°, 30°, 45°, and 60°. The findings indicate that the mechanical response varies systematically with lithology and fracture inclination. The post-peak curves differ significantly among rock types: coal–rock shows a gentle descent, mudstone exhibits a rapid strength drop but higher residual strength, and sandstone is characterized by “serrated” fluctuations. The failure mode transitions from tensile splitting at a horizontal inclination of 0° to shear failure at inclinations of 15°, 30°, 45°, and 60°. Strain nephograms corresponding to the peak stress point D reveal sharp, band-shaped zones of strain localization. The maximum principal strain exhibits a non-monotonic trend, first increasing and then decreasing with increasing inclination angle. For grouted coal–rock and sandstone, the peak values of 47.47 and 45.00 occur at α = 45°. In contrast, grouted mudstone reaches a maximum value of 26.80 at α = 30°, indicating its lower susceptibility to damage. The study systematically clarifies the strain evolution behavior of grouted fractured rock masses, providing a theoretical basis for evaluating the effectiveness of reinforcement and predicting failure mechanisms. Crucially, the findings highlight mudstone’s role as a high-integrity medium and the particular vulnerability of horizontal fractures, offering direct guidance for the targeted grouting design in stratified rock formations. Full article

Cemented granular materials (CGMs) represent a transitional class of geomaterials where mechanical behavior is governed by the interplay between a discrete granular skeleton and a continuous cementitious matrix. While previous studies have focused on idealized spherical particles, this study aims to quantify the influence of the cement filling ratio (ranging from 10% to 100%) on the mechanical constitutive behavior of CGMs fabricated with large, irregular granitic aggregates (14–20 mm). Unconfined compressive tests and splitting tensile tests were conducted to evaluate the evolution of strength, stiffness, and failure modes. The results reveal a distinct mechanical transition governed by the cement filling ratio (${\rho }_m$). The elastic modulus and splitting tensile strength exhibited a linear increase with ${\rho }_m$ (R2 > 0.95), indicating a direct dependence on the volume fraction of the binding phase. In contrast, the unconfined compressive strength (UCS) and peak strain displayed a bilinear growth pattern with a critical inflection point at ${\rho }_m$ = 80%. For the specific irregular granitic aggregate skeleton investigated, this threshold marks the transition from contact-dominated stability to matrix-dominated continuum behavior. Below this threshold, strength gain is limited by the stability of discrete particle contacts; above 80%, the material behaves as a continuum, with UCS increasing rapidly to a maximum of 41.78 MPa at 100% filling. Furthermore, the dispersion of stress–strain responses significantly decreased as ${\rho }_m$ exceeded 50%, attributed to the homogenization of stress distribution within the specimen. These findings provide a quantitative basis for optimizing cement usage in ground reinforcement applications, identifying 80% as a critical design threshold. Full article

This study presents a comprehensive numerical investigation into the dynamic response of railway precast concrete slab track (PST) systems subjected to various interlayer gap conditions. Key parameters including gap width, depth, and location were examined, along with the geometric configuration of the grouting layer, comparing current (as-is) and earlier (as-was) models. A conservative modeling approach was adopted, assuming fully unbonded interfaces and delamination gap depths extending to the shear key, with dynamic loading applied. Results showed that the maximum principal stress in both the slab and grouting layer increased with larger gap widths but stabilize beyond specific thresholds. In the as-is model, stress levels remained below reference flexural tensile strength, indicating a low risk of cracking. However, the as-was model exhibited grouting layer stresses exceeding the allowable limit at the gap widths near 4 mm and approaching critical levels even at 1.5 mm. Stress responses also varied depending on whether gaps were located at the slab–grouting layer or grouting layer–hydraulic stabilized basecourse (HSB) interfaces. Based on the examinations, allowable interlayer gap width criteria were proposed to support maintenance decisions. The study provides a rational framework for monitoring and managing interlayer gaps, enhancing resistance to early fatigue cracking and structural integrity of PST systems under dynamic railway loads. Full article

This study evaluates the effects of hydrothermal and oleothermal treatments on the physical, colorimetric, and mechanical properties of Dabema wood. Samples were heated at 100, 160, and 220 °C for 2, 3.5, and 5 h. Equilibrium moisture content decreased from 13.16% in untreated wood to approximately 43% lower after hydrothermal treatment at 160 °C for 5 h and to 64% lower after oleothermal treatment at 220 °C for 5 h. Water absorption decreased from 78% in untreated samples to 25%–64% following hydrothermal treatment and to 17%–44% after oleothermal treatment. Hydrothermal treatment caused significant darkening, whereas oleothermal treatment maintained a lighter, more stable color. Mechanical properties improved substantially: in compression, MOE increased by 113% after oleothermal treatment at 220 °C for 5 h. In bending, MOR and MOE rose by 25%–35% under optimal oil-heat conditions. In tensile, MOE increased by 30%, and maximum tensile stress improved by up to 130%. Oleothermal treatments yielded the most stable enhancements, whereas severe hydrothermal treatments sometimes reduced mechanical performance despite improving moisture resistance. Multivariate analysis (PCA) and response surface methodology (RSM) indicate that oleothermal treatment at 160 °C for 3.5–5 h provides the best compromise between stiffness and color stability. Thermogravimetric analyses (TG/DTG) show hydrothermal treatment promotes hemicelluloses degradation, whereas oleothermal treatment stabilizes the cellulose–lignin network. Overall, hydrothermal treatment enhances dimensional stability, while oleothermal treatment achieves an optimal balance of stiffness, mechanical performance, and color retention. Deep color changes from furanic resin formation under hydrothermal conditions are strongly suppressed by oil during oleothermal processing, yielding lighter and more durable wood. For commercial applications such as furniture and structural components, oleothermal treatment is recommended, whereas hydrothermal treatment is more suitable when dimensional stability is prioritized over mechanical performance. Full article

Additive manufacturing has been adopted in several industries including the medical field to develop new personalised medical implants including tissue engineering scaffolds. Custom patient-specific scaffolds can be additively manufactured to speed up the wound healing process. The aim of this study was to design, fabricate, and evaluate a range of materials and scaffold architectures for 3D-printed wound dressings intended for soft tissue applications, such as skin repair. Multiple biocompatible polymers, including polylactic acid (PLA), polyvinyl alcohol (PVA), butenediol vinyl alcohol copolymer (BVOH), and polycaprolactone (PCL), were fabricated using a material extrusion additive manufacturing technique. Eight scaffolds, five with circular designs (knee meniscus angled (KMA), knee meniscus stacked (KMS), circle dense centre (CDC), circle dense edge (CDE), and circle no gradient (CNG)), and three square scaffolds (square dense centre (SDC), square dense edge (SDE), and square no gradient (SNG), with varying pore widths and gradient distributions) were designed using an open-source custom toolpath generator to enable precise control over scaffold architecture. An in vitro degradation study in phosphate-buffered saline demonstrated that PLA exhibited the greatest material stability, indicating minimal degradation under the tested conditions. In comparison, PVA showed improved performance relative to BVOH, as it was capable of absorbing a greater volume of exudate fluid and remained structurally intact for a longer duration, requiring up to 60 min to fully dissolve. Tensile testing of PLA scaffolds further revealed that designs with increased porosity towards the centre exhibited superior mechanical performance. The strongest scaffold design exhibited a Young’s modulus of 1060.67 ± 16.22 MPa and withstood a maximum tensile stress of 21.89 ± 0.81 MPa before fracture, while maintaining a porosity of approximately 52.37%. This demonstrates a favourable balance between mechanical strength and porosity that mimics key properties of engineered tissues such as the meniscus. Overall, these findings highlight the potential of 3D-printed, patient-specific scaffolds to enhance the effectiveness and customisation of tissue engineering treatments, such as meniscus repair, offering a promising approach for next-generation regenerative applications. Full article

In this work, a laser lap-welded joint of galvanized steel/Mg and a laser lap-welded joint of galvanized steel/Mg assisted by ultrasonic vibration were compared. By adjusting the laser beam power and ultrasonic amplitude, the appropriate welding process parameters were obtained. The weld formation, microstructure and mechanical properties were studied and analyzed. The results indicated that the addition of ultrasonic vibration generated an excitation force with a certain frequency and amplitude on the weldment, making the molten metal in the molten pool produce ultrasonic forced vibration, and producing the effects of cavitation, acoustic streaming, mechanical stirring and heat, thus reducing welding residual stress and welding-deformation, porosity and incomplete-fusion defects. In addition, it can make the fusion zone transition evenly, improve the wettability, refine the weld grain, and reduce the average grain area from 583 μm² to 324 μm². Moreover, the distribution of Mg-Zn reinforcing phase at the interface was more uniform and denser, and the maximum tensile shear strength increased from 179.9 N/mm to 290 N/mm, indicating that the addition of ultrasonic vibration was conducive to improving the comprehensive mechanical properties of the joint. Full article

This study analyzes the mechanical behavior of a quasi-isotropic biaxial glass fiber–vinyl ester composite in a multiaxial stress condition and the effect of the orientation of the fibers. A ply structure was created through the process of vacuum infusion using six layers of biaxial fabric that were oriented to 15°. Tensile samples were isolated at 0, 15, 30, 45 and 90 degrees relative to the warp direction. It was found that strength and stiffness strongly depend on orientation, with maximum tensile strengths of 157.2 MPa at 90° and 125 MPa at 0°, and minimum tensile strengths 59.6 MPa at 15°, showing fiber and shear failures, respectively. MAT_124 underwent finite element analysis in LS-DYNA, and the results were excellent, with a difference of less than 1.5%. Three-point bending and Charpy impact tests indicated that flexural properties were lower at 15° and 90°, whereas off-axis orientations were generally better at impact energy absorption, although at 45°, binding sites were few and far between. The results have important implications for the design of laminates subjected to complicated loads. Full article

Blast-induced vibrations from newly constructed tunnels may adversely affect adjacent existing tunnel structures. To ensure the safety of the existing tunnel, it is essential to investigate its dynamic response under blast disturbances. Based on an expansion project for a highway double-arch tunnel, this study employed the dynamic finite element program LS-DYNA to analyze the vibration velocity and effective stress in the tunnel lining subjected to blast vibrations. The distribution characteristics of vibration velocity and effective stress at different locations of tunnel lining were obtained. A relationship model between the peak particle velocity (PPV) and effective stress was established. According to the maximum tensile stress theory, a safety criterion based on vibration velocity was determined. To facilitate field monitoring, a correlation between the vibration velocity at the arch waist and foot was established, leading to a proposed safety threshold for the arch foot vibration velocity. Furthermore, a statistical relationship was developed between the charge weight per hole in the upper bench cut and the vibration velocity at the arch foot to guide blasting design. Using the arch foot vibration velocity as the safety standard, the maximum permissible charge weight to ensure the structural safety of the existing tunnel was recommended. Full article

This study examines the influence of build orientation on the mechanical behavior of 316 stainless steel components fabricated by selective laser melting (SLM). Additively manufactured tensile specimens produced in different build orientations were experimentally analyzed and compared with reference specimens obtained from conventionally hot-rolled material and laser-cut to identical geometries. Uniaxial tensile testing combined with digital image correlation (DIC) was employed to evaluate the mechanical response and full-field strain evolution. Microstructural features were investigated using scanning electron microscopy (SEM), while phase composition was assessed by X-ray diffraction (XRD). The results reveal a pronounced orientation-dependent mechanical anisotropy in the SLM specimens, reflected in variations in yield strength, ultimate tensile strength, and ductility. Specimens loaded perpendicular to the build directions exhibited higher strength but reduced ductility compared to those loaded parallel to the build direction, whereas the rolled material showed a more isotropic mechanical response. Although the XYZ and XZY samples feature similar deposition patterns, the XRD analysis revealed a the existence of a $\left[220\right]$ texture. Thus, the mechanical performances of XZY specimens are about $10\%$ lower compared to XYZ printed samples. The stress maximum–strain curves were extrapolated from the true data using the Swift model. The section dedicated to numerical modeling includes a failure model based on the traixility. The numerical models were validated for the range $\eta \in \left[0.33\dots 0.45\right]$ specific to uniaxial tension. Fractographic observations further confirmed the correlation between build orientation, microstructural features, and fracture behavior. The present study provides a multiscale experimental framework linking processing conditions, microstructure, and mechanical response in additively manufactured stainless steel. Full article

We investigate the mechanical properties of electrospun boron nitride nanotube (BNNT)-reinforced silica nanocomposite microfibers. The incorporation of small amounts of BNNTs (0.1, 0.3, and 0.5 wt.%) into silica results in significant enhancements in the bulk mechanical performance, including up to a 26.4% increase in Young’s modulus, a 19.4% increase in tensile strength, and a 12.8% increase in toughness. These improvements are attributed to the excellent nanotube alignment achieved via electrospinning and the effective transfer of interfacial loads at the BNNT–silica interface. Micromechanical analysis based on in situ Raman measurements reveals that the maximum interfacial shear stress in the electrospun BNNT–silica microfiber reaches about 341 MPa. This study provides new insights into the process–structure–property relationship and reinforcement mechanisms in nanotube-reinforced ceramic nanocomposites, thereby advancing the development of lightweight, strong, tough, and durable ceramic materials. Full article

To tackle the limitations of conventional seismic design in high-intensity zones, as well as the challenges of inadequate isolation efficiency, excessive bearing displacement, and tensile stress in seismically isolated high-rise structures, this study presents a systematic solution for high-rise shear wall structures in seismic intensity 8 zones. The solution features a sparse isolator layout strategy, reducing isolator count by 40% to lower stiffness, while adding viscous dampers in the isolation layer for enhanced displacement control. Comparative nonlinear time history analyses were conducted to evaluate the inter-story shear distribution, energy dissipation allocation, and isolator responses. The results show that (1) the sparse layout achieves the best performance in controlling the bottom shear ratio and Maximum Considered Earthquake (MCE)-level responses (including displacement and tensile stress); (2) viscous dampers significantly reduce the shear forces in the lower stories and the energy dissipation of both isolators and the superstructure; (3) the combined strategy successfully resolves the issues of excessive isolator displacement and tensile stress under MCE. This research offers a standardized, economical, and highly resilient technical approach for seismically isolated high-rise projects in high-intensity seismic regions. Full article

As research on fiber-reinforced concrete progresses, investigating the enhancement effect of hybrid fiber-reinforced concrete becomes increasingly crucial. In the present research, the contents of steel fiber (SF) and polypropylene fiber (PP) were set as variable parameters to study the mechanical performance of steel-polypropylene hybrid fiber-reinforced concrete (SPFRC). Mechanical performance tests were undertaken on 16 groups of standard specimens. The failure modes were observed, the strength variation patterns were analyzed, and both a strength prediction equation and a complete stress–strain curve equation were established. Research results indicated that the specimen containing 1.5% SF and 0.25% PP exhibited the maximum strength enhancement compared with plain concrete: cube compressive strength improved by 27.78%, and splitting tensile strength surged by 41.18%. When the SF content was 1.5% and that of PP was 0.5%, the specimen’s elastic modulus experienced the greatest enhancement, reaching 58.59%. Hybrid fibers significantly enhanced the mechanical performance of SPFRC, simultaneously exerting strengthening, crack-resistance, and toughening effects. The research findings offer both experimental evidence and theoretical support for promoting research and engineering applications of SPFRC. Full article

For massive monolithic foundation slabs, the risk of early cracking during construction is a pressing issue. This problem is primarily caused by thermal stresses arising from uneven heating of the structure during concrete curing and cooling. The most common approach to assessing thermal stresses is to express them through the temperature difference between the center and surface of the structure. However, this approach fails to take into account that heat transfer conditions on the upper and lower surfaces of the slab may differ. The purpose of this article is to derive calculation relationships that allow thermal stresses to be expressed through temperatures at three characteristic points on the slab: at the lower surface, in the middle of the slab, and at the upper surface. The resulting formulas were validated by comparison with the results of finite element analysis and an experiment presented in the work of other authors. Compared to the results of finite element analysis, the error in determining the maximum tensile stresses at the center of the slab is 0.4%. To assess the applicability limits of the resulting formulas, a series of finite element calculations were also performed for various slab thicknesses. It was established that for a slab thickness of up to 2 m, the error in determining stresses at three characteristic points using the authors’ formulas does not exceed 10%. Full article