Search Results (8,068)

Water scarcity in semi-arid regions threatens seed germination and early crop establishment, driving the development of biodegradable Nature-based Solutions to replace synthetic plastic mulches. Porous cellulose membranes were fabricated from rice husk (RH), banana pseudostem (BP), and sugarcane bagasse (SB) by thermo-chemical extraction and high-shear homogenization (n = 5 replicates per membrane type). Membranes were characterized by ATR-FTIR and scanning electron microscopy, confirming removal of non-cellulosic components and biogenic silica preservation in RH, and revealing biomass-dependent porous architectures linked to mechanical and transport behavior. RH produced the most compact fibrillar matrix (compressive strength: 8.16 ± 0.24 MPa; WVT: 170 ± 60 g m⁻² day⁻¹), BP an open interconnected network with superior deformability (9.83 ± 0.25% elongation) and moisture transport (WVT: 400 ± 100 g m⁻² day⁻¹), and SB the highest moisture-retention capacity (215.7 ± 15.8%). Germination assays with Brassica oleracea var. botrytis under water stress showed SB achieved the highest germination rate (90.5 ± 0.99%), confirming that sustained moisture availability governs germination more decisively than transport rate alone. Soil burial tests confirmed biodegradable behavior across all membranes (R² ≥ 0.995; k = 0.043–0.046 day⁻¹). These findings establish a hydrogen-bond-mediated structure–property–function framework for designing biomass-specific cellulose membranes as biodegradable solutions for water-limited agricultural systems. Full article

This paper presents a three-dimensional generalization of the M-integral, formulated as an interaction integral based on a bilinear strain energy density, for the mixed-mode decoupling of crack front energies in finite structural components. The proposed $M_{\theta }^{3D}$ integral combines real and virtual mechanical fields within a local spherical reference frame, enabling the separate evaluation of mode I (opening), mode II (in-plane shear) and mode III (out-of-plane shear) energy release rates along arbitrary crack front lines. The theoretical framework, derived from Noether’s theorem and the virtual work principle, is implemented in the Cast3M finite element code using a toroidal integration domain with a local theta weighting function. Numerical validations are conducted on the Mixed-Mode Crack Growth (MMCG) specimen, a geometry representative of structural components subjected to combined tension and shear. Three key findings are demonstrated: (i) practical domain independence is achieved for all three fracture modes; (ii) the three-dimensional approach converges to the plane-stress solution for thin specimens and reveals significant deviations from plane-strain assumptions; (iii) even under nominally mode I + II loading, a non-negligible mode III component emerges due to Poisson-induced out-of-plane effects, with magnitude increasing at free surfaces and for thicker geometries. These results indicate that finite-thickness and out-of-plane effects can significantly affect the partition of fracture energy between modes. For the MMCG configuration investigated here, the three-dimensional formulation shows the limitations of two-dimensional assumptions and provides an energetic basis for the analysis of mixed-mode fracture in finite-thickness components. Full article

The design of intravascular ultrasound (IVUS) catheters involves inherently coupled acoustic, hemodynamic, and structural requirements. Existing design strategies, which often rely on empirical geometric refinement or single-physics optimization, are limited in their ability to simultaneously ensure acoustic transmission efficiency, flow compatibility, and mechanical reliability. A multiphysics topology optimization method for the integrated design of IVUS catheters under acoustic–fluid–structure interactions is proposed in this paper. A density-based design variable is introduced to characterize the material distribution within the design domain, and consistent interpolation schemes are employed to relate this variable to the effective acoustic properties in the Helmholtz equation, the Brinkman penalization coefficient in the incompressible Navier–Stokes equations, and the elastic stiffness tensor in the structural equilibrium equation. The optimization problem is formulated as a normalized multi-objective minimization of acoustic transmission loss, flow resistance, and structural compliance, subject to constraints on material volume, received acoustic energy, wall shear stress, and structural displacement. Density filtering and smooth Heaviside projection are incorporated to regularize the design field and promote well-defined material boundaries. An adjoint sensitivity formulation is further developed to enable efficient gradient evaluation for the coupled system. Compared with the initial design, the average acoustic transmission efficiency has increased by $59.01\%$, the shear stress has decreased by $53.87\%$, and the stiffness matching rate has reached $98.27\%$. The objective function converged after 35 iterations, demonstrating the numerical stability of the proposed acoustic–fluid–structure topology optimization framework. Full article

After cold rolling of high-strength interstitial-free (IF) steel, the ferrite grains undergo plastic deformation associated with the formation of substructures and intense cold-rolling texture, which affects the microstructure and texture in the subsequent annealing process and determines the formability of the final sheet. To clarify the mechanisms of microstructure and texture formation during cold rolling of IF steel, a polycrystalline model was constructed based on the measured microstructure and texture features. A crystal plasticity model, along with a remeshing technique, was developed for IF steel. The model can calculate the deformation of the polycrystal after 70% cold rolling reduction, in which the calculated microstructure and texture features are consistent with the results from electron backscatter diffraction (EBSD). The results show that the deformed microstructure and texture are closely related to the initial crystal orientation, the interaction between neighbouring grains, and the cold rolling reduction. Grains with an initial texture orientation near <001>//ND are more stable during deformation and tend to retain their orientations after cold rolling. In contrast, grains initially deviating from the γ-fiber tend to rotate towards the <111>//ND orientation, while near-γ-fiber grains mainly retain their γ-fiber characteristics with intragranular orientation spreading during cold rolling. Multiple slip systems induce the formation of ingrain shear bands. These results establish a grain-scale link between initial orientation, intragranular substructure formation, and cold rolling texture evolution, and provide a mechanistic basis for optimizing cold rolling texture control and improving the formability of high-strength IF steel sheets. Full article

The frictional behavior and stability of skid shoe systems are critical to the safety and controllability of walking-type incremental launching for long-span steel truss bridges. Therefore, this study investigates friction control mechanisms and multilayer pad stability through two tests: (1) skid shoe tests to evaluate low-friction performance, sliding stiffness, and the stability of stacked pad assemblies, and (2) interface friction tests to examine the frictional behavior of different material combinations intended to provide high-friction restraint. The results show that Modified Graphene-Enhanced (MGE) plates, when combined with grease and stainless steel, reduce the friction coefficient to 0.017–0.074. High-stack pad assemblies (6–16 layers) exhibited a progressive interlayer slip, with cumulative displacements exceeding the allowable limit, leading to instability; anti-slip measures such as shear keys and segmented restraints were recommended. A load-dependent sliding stiffness relationship, y = 57.46 + 0.00886x, was established to characterize the variation in nominal sliding stiffness with vertical load. The findings provide experimental data and engineering recommendations for the design and operation of skid shoe systems in heavy-load incremental launching applications. The proposed criteria and regression model are applicable to the tested pad geometry, interface configuration, and loading conditions investigated in this study. Full article

Rectangular piles are increasingly utilized in engineering due to their high lateral bearing capacity, which benefits from an adjustable cross-sectional stiffness. However, research on rectangular piles within slope topography remains relatively scarce. Therefore, based on the principle of equal cross-sectional area, this paper establishes four sets of finite element models for rectangular piles with varying aspect ratios to conduct numerical analyses of their bearing characteristics under combined loading at slope angles of 0°, 15°, 20°, and 30°. The results demonstrate that: (1) Under combined loading, the lateral and vertical bearing capacities of rectangular piles interact; as the loading angle increases, the lateral bearing capacity decreases while the vertical bearing capacity increases. (2) Increasing the aspect ratio can significantly enhance the bearing capacity of rectangular piles. Under flat-ground conditions, compared to a pile with an aspect ratio of 1, a rectangular pile with an aspect ratio of 4 exhibits a roughly 75% increase in ultimate lateral bearing capacity and a 15.8% increase in vertical bearing capacity. (3) The critical section of the pile typically occurs within a depth range of 0.28 L to 0.43 L, where its stress mode gradually transitions from predominantly lateral bending and shearing to primarily vertical axial compression. (4) Slopes induce a reduction in the pile’s bearing capacity, but the bearing capacity curve for the pile with an aspect ratio of 4 declines more gently. Thus, rectangular piles with large aspect ratios possess greater engineering applicability in slope topography. This study reveals the bearing mechanism of rectangular piles under the combined influence of the slope weakening effect and the cross-section enhancement effect, providing a methodological reference for the design and application of novel pile foundations in slope terrains. Full article

Seasonal freeze–thaw cycling progressively rearranges pores and propagates microcracks in silty clay, reducing the reliability of cold-region earthworks. This study evaluated a bio–polymer stabilization strategy combining microbially induced carbonate precipitation (MICP) with anionic polyacrylamide (APAM) to improve mechanical performance and freeze–thaw durability. Six groups were prepared at identical moisture and compaction conditions: water, APAM, and four MICP–APAM groups with bacterial optical densities (OD600) of 0.8, 1.0, 1.2, and 1.4. Unconfined compressive strength, unconsolidated-undrained triaxial compression, ultrasonic pulse velocity, and SEM, TG/DTG, XRD, and FTIR analyses were conducted before and after freeze–thaw cycling. The M1.0-APAM group showed the best overall performance, with UCS values of 1.35 MPa before cycling and 0.89 MPa after nine cycles, together with high shear resistance and ultrasonic velocity. Lower bacterial concentration provided insufficient cementation, whereas higher concentrations promoted non-uniform carbonate deposition, pore heterogeneity, and local stress concentration. Microstructural evidence indicated that OD600 ≈ 1.0 produced a relatively homogeneous network of fine carbonate clusters and polymer-associated films, with calcite formation supported by TG/DTG and XRD. The results show that MICP–APAM treatment enhances silty clay primarily through coordinated mineralization uniformity, pore refinement, and polymer bridging, providing a sustainable stabilization option for seasonally frozen soils. Full article

This study comprehensively evaluates the mechanical properties, shrinkage behavior, and durability of concrete prepared with limestone- and granite-manufactured sands under standard-curing and steam-curing conditions. The results indicate that limestone-manufactured sand concrete consistently exhibits superior compressive strength and splitting tensile strength across all curing ages, outperforming granite-modified counterparts. The introduction of granite-manufactured sand significantly degrades these mechanical properties, with deterioration intensifying as granite content increases. Dynamic elastic modulus and damping ratio analyses reveal that limestone-based concrete maintains the highest dynamic stiffness and lowest energy dissipation under both curing regimes, suggesting fewer internal defects. In contrast, granite incorporation reduces the dynamic elastic modulus and increases the damping ratio, reflecting structural deterioration and enhanced energy loss. Drying shrinkage tests demonstrate that limestone concrete achieves the lowest shrinkage deformation throughout the testing period, even under steam-curing conditions. Conversely, granite addition markedly elevates shrinkage, particularly under steam-curing conditions, leading to compromised volumetric stability. Durability assessments highlight that manufactured sand concrete exhibits higher capillary absorption, electrical flux, and porosity, attributed to inherent material defects and the surface characteristics of manufactured sand. Granite-modified concrete further weakens interfacial shear strength between aggregates and cement paste, indicating poor interfacial bonding. Steam curing exacerbates microstructural defects, emphasizing the need to optimize curing protocols. The findings propose strategies for enhancing manufactured sand concrete performance: improving interfacial adhesion between aggregates and cement paste, rationalizing supplementary material dosages, and refining steam curing regimes. These measures offer potential pathways to develop high-performance manufactured sand concrete with balanced mechanical and durability properties. Full article

Dense granular materials under low confining stress and low shear velocity—conditions relevant to low-pressure powder handling, near-surface transport, and the upper layers of stored bulk solids—remain insufficiently characterized at the microstructural level. We perform three-dimensional discrete element method (DEM) simulations of annular shear of monodisperse glass spheres at σ = 1 kPa and v = 0.01 m/s, corresponding to an inertial number I ≈ 1.06 × 10⁻³ at the quasi-static limit of the dense flow regime. The steady-state friction coefficient stabilizes at μ_ss ≈ 0.78, consistent with the quasi-static limit of the μ(I) framework. The solid volume fraction decreases monotonically from φ ≈ 0.50 at the base to φ ≈ 0.35 near the top, while the tangential velocity decays exponentially with depth (decay length δ_s ≈ 10 mm). Particle trajectory tracking reveals a sharp kinematic transition near z ≈ 5–6 mm separating a quasi-rigid basal layer (z ≲ 5 mm) from an upper shear-active zone (z ≳ 6 mm). The contact force distribution follows an exponential decay P($f$/$⟨f⟩$) ∝ exp(−β·$f$/$⟨f⟩$) with β ≈ 0.45, with strong force chains selectively concentrated in the upper zone. Together, these four microstructural descriptors co-locate within a single transition band, providing quantitative benchmarks for material characterization and constitutive modelling at the lower boundary of dense flow. Full article

The poor engineering properties of Gobi soil, such as low strength and poor water stability, pose challenges for foundations in arid regions, especially large photovoltaic plants. This study examines the effect of polypropylene (PP) fiber reinforcement on Gobi soil from Dabancheng, Xinjiang. Laboratory tests including unconfined compressive strength, direct shear (orthogonal experimental design), slake durability, and scanning electron microscopy were performed to investigate the influences of fiber length (6, 9, 12 mm), fiber content (0.3–1.1% by dry soil mass), and water content (4–12.5%). Results indicate that PP fibers change the failure mode from brittle to ductile. The optimal combination (9 mm fiber length, 0.7% content, and Proctor optimum water content of 10.5% corresponding to maximum dry density) improves cohesion by 122% (reinforcement coefficient K = 2.22). Moreover, fibers alter the disintegration behavior from complete to stable partial disintegration; the 12 h disintegration ratio decreases from 100% to 13% under optimal conditions. Microstructural analysis shows that an appropriate fiber content creates a uniform three-dimensional reinforcing network, enhancing mechanical interlocking and fiber bridging, whereas excessive fiber leads to agglomeration and increased pore connectivity, degrading overall performance. This study provides a low-carbon, sustainable soil stabilization method and practical design parameters for Gobi desert infrastructure. Full article

Mechanical circulatory support (MCS) has transformed the management of advanced heart failure; however, device-related morbidity remains substantially driven by adverse interactions occurring at the blood–material and tissue–device interfaces. Despite progressive miniaturization and the evolution from first-generation pulsatile systems to contemporary continuous-flow devices, thrombotic, hemorrhagic, infectious, and inflammatory complications continue to limit long-term outcomes. This review examines the mechanistic contribution of material properties, surface architecture, and hemodynamic conditions to the pathogenesis of major MCS-associated complications, with particular emphasis on thrombogenicity, biomaterial-induced inflammatory activation, driveline and cannulation-associated infections, hemocompatibility disturbances, and device-related structural failure. The interplay between protein adsorption, platelet activation, complement cascade dysregulation, disturbed shear profiles, and biofilm formation is analyzed as a central determinant of adverse clinical events. Special attention is given to pediatric MCS, in which the continued reliance on extracorporeal pulsatile systems, unique anatomical constraints, and narrow therapeutic margins intensify susceptibility to both thromboembolic and infectious sequelae. Furthermore, the review addresses how material and surface modifications, and emerging biomimetic and anti-thrombogenic coatings may influence complication mitigation. By integrating clinical, engineering, and biomaterials perspectives, this work highlights that many complications traditionally regarded as secondary clinical phenomena are fundamentally rooted in device–material interactions and flow-mediated biological responses. Improved understanding of these mechanisms is essential for optimizing device design, enhancing hemocompatibility, and reducing complication burden in both adult and pediatric MCS populations. Full article

Metallic glasses (MGs) exhibit excellent mechanical properties, yet their poor tensile ductility greatly limits their practical applications as structural and functional materials. Shear banding is a typical localized rheological deformation behavior inherent to amorphous materials, which stems from heterogeneous atomic rearrangement and regional viscosity fluctuations in the glassy matrix, and fundamentally determines the macroscopic mechanical properties of MGs and their composites. This review discusses the relationship between typical toughening strategies and shear banding behavior, and proposes that deliberate suppression of shear band (SB) initiation or deceleration of their rapid propagation can effectively promote distributed plastic flow. In this review, nanosizing and metamaterial strategies are shown to hinder the formation of mature SBs, while metallic glass matrix composites (MGMCs), nanoglasses (NGs), notched design, and rejuvenation treatments contribute to restraining SB propagation. Current approaches have successfully regulated shear banding behavior and thereby realized appreciable tensile ductility in MGs. Novel design and fabrication techniques for amorphous alloys, which suppress SB initiation and retard SB propagation to achieve homogeneous plastic flow, open up new avenues for realizing controllable plasticity of MGs. Full article

Salt rock exhibits pronounced viscoelastic creep, continuously imposing radial extrusion loads on casing and threatening long-term well integrity. Field observations in the Missan Oilfield, Iraq, show that casing damage is concentrated near salt–non-salt interfaces, where lithologic contrasts intensify stress redistribution and mechanical coupling. This study integrates triaxial creep experiments, a calibrated modified Burgers model, UMAT implementation, and three-dimensional finite element simulations to investigate casing stress evolution and failure mechanisms. The calibrated model reproduces salt rock creep with a maximum relative strain error of 16.8%. Results show that post-cementing salt creep amplifies non-uniform radial loading at the interface, causing progressive casing stress concentration. At low inclination, the interface–casing intersection evolves into an elliptical annulus; the circumferential variation in equivalent wall thickness and stress-peak migration jointly weaken local stress concentration. However, when the inclination angle reaches approximately 45° at β = 0°, the peak Mises stress begins to exceed that under the vertical-well condition. When α ≥ 65°, the peak stress no longer decreases monotonically with azimuth but exhibits a decrease–increase trend. This indicates that eccentric loading and the additional bending moment dominate the transition from radial extrusion to coupled bending–shear–extrusion loading. A casing stress risk map and grade-selection chart are developed to support casing design in salt-interbedded formations. Full article

Diamane, a fully sp³-hybridized two-dimensional carbon allotrope, has attracted attention due to its exceptional mechanical strength, tunable electronic properties, and potential for nanoelectronic and nanomechanical applications. While most studies focus on semi-functionalized (50% surface functionalization) C₄X₂ diamane, the stability and properties of configurations with lower functional group coverage remain unexplored. Here, we propose a novel diamane structure with 25% surface functionalization, denoted as C₄X (X = H, F, OH, NH₂), crystallizing in the P6/mmm space group. Using first-principles calculations, we systematically investigate the effects of different functional groups on the electronic and mechanical properties. Our results show that the bandgap can be effectively tuned from 2.97 to 3.42 eV, with C₄F and C₄OH exhibiting wider gaps due to strong C-p and O(F)-p orbital hybridization. C₄H and C₄NH₂ possess high electron mobilities on the magnitude order of of ${10}^3$ cm² V⁻¹ s⁻¹. Mechanically, C₄H demonstrates a Young’s modulus up to 614 GPa and a shear modulus of 274 GPa, underscoring its exceptional mechanical robustness. This work uncovers a previously unexplored low-coverage diamane configuration, highlighting the crucial role of surface chemistry in modulating electronic and mechanical behavior, and provides a promising design strategy for high-performance carbon-based nanoelectronic and nanomechanical devices. Full article

3D-printed continuous carbon fiber-reinforced polylactic acid (CF/PLA) composites combine the high load-bearing capability of continuous fibers with the structural design freedom of additive manufacturing, showing broad application prospects in lightweight complex structures. However, the chemically inert surface of carbon fibers and their insufficient interfacial compatibility with the PLA matrix lead to inefficient interfacial load transfer, thereby limiting the mechanical performance of the composites. In this study, a waterborne polyurethane (WPU)-based sizing treatment was applied to carbon fibers to enhance the fiber–matrix interface of 3D-printed continuous CF/PLA composites. The WPU sizing layer increased fiber-bundle cohesion and introduced a transition region between CF and PLA through possible hydrogen bonding, dipolar interactions, and physical adhesion. When the nominal WPU concentration was 5 wt%, the apparent interfacial shear strength reached 1.31 MPa, representing an improvement of approximately 65% compared with ACF/PLA. The three-point flexural strength reached 69.76 MPa, which was 55.3% higher than that of the ACF/PLA composite. These results indicate that WPU sizing is an effective and scalable interfacial regulation strategy for improving the mechanical properties of 3D-printed continuous CF/PLA composites. Full article