Search Results (915)

The structural lightweighting of next-generation containerized energy storage systems requires reliable fatigue design methodologies for architected lattice materials subjected to complex multiaxial service loading. Despite extensive studies on static performance, fatigue capacity prediction of parameterized lattices remains computationally demanding and experimentally fragmented, particularly when cyclic characteristics cannot be idealized as simple periodic histories. This work develops a unified multiscale evaluation platform grounded in shakedown theory to directly predict multiaxial fatigue capacity for lattice structures without explicit cycle counting. A topology-agnostic nodal-coupling periodic boundary formulation ensures consistent homogenized response evaluation across diverse unit-cell geometries. Numerical robustness in stress computation is achieved through full-integration tetrahedral discretization (FITD), enabling stable treatment of bending-dominated lattice members. To facilitate rapid exploration of high-dimensional design spaces, an ensemble-learning surrogate is trained on multiscale shakedown datasets for capacity prediction and parameter sensitivity analysis. The framework is demonstrated on body-centered cubic and peanut-like auxetic lattices relevant to lightweight container structures. Validation studies confirm accurate FITD scheme-based shakedown fatigue loading prediction. The surrogate model achieves high predictive precision, and parametric analysis reveals topology-dependent fatigue drivers, establishing quantitative linkages between mesoscale geometric variables and shakedown-based fatigue capacity. The proposed methodology provides an efficient and scalable route for fatigue-oriented lattice design and optimization in energy storage container applications. Full article

Clayey soils are generally characterized with low strength and high plasticity which may affect the stability of the subgrade in road infrastructure and hence encourage research into sustainable stabilization techniques. The objective of this study was to investigate the possibility of using recycled crumb rubber (CR) mixed with biaxial geogrid reinforcement to enhance the engineering performance and interface shear behaviour of problematic clayey soil. The experiments were performed on biaxial geogrid BX1100, waste crumb rubber, clay subgrade soil, type B subbase granular material and other materials. The subgrade soil of clay has been collected from the airport area of Al-Muthanna region, Baghdad. An extensive programme of laboratory tests was conducted on soil mixtures with 5%, 10% and 15% of crumb rubber (CR) and untreated soil to determine the effect of stabilization with crumb rubber. The protocol consisted of Atterberg limits, modified Proctor compaction, California Bearing Ratio (CBR) and large-scale direct shear testing. The results showed that the engineering properties of the clay soil were improved by using CR. Maximum improvement was observed at 15% CR content where CBR increased by 56.6% and plasticity index decreased by 44% over the untreated soil. In addition, the large-scale direct shear tests showed that the interface shear strength increased with increasing CR content under geogrid reinforcement. The calculated interaction coefficients were greater than unity for all the tested mixtures indicating effective bonding and interlocking between the reinforced soil layers. The results indicate that the synergistic effect of CR and geogrid reinforcement could improve the interface behaviour of the weak clay subgrade soils with sustainable reuse of waste tyre rubber. Full article

The effect of internal pressure on the layered microstructural evolution of N36 zirconium alloy cladding tubes was systematically studied under simulated loss-of-coolant accident (LOCA) biaxial creep conditions at 900 °C. The tested specimens were characterized by electron channeling contrast imaging, energy-dispersive X-ray spectroscopy, electron backscatter diffraction, and transmission electron microscopy. The results show that all specimens formed a typical layered cross-sectional structure consisting of an oxide film, an oxygen-rich α-Zr (α(O)) layer, and a prior-β transformed layer. The thickness of the α(O) layer and the oxygen diffusion depth changed markedly with internal pressure. The thickness of the α(O) layer was approximately 21 μm for the 0.8 MPa specimen and 11 μm for the 1.9 MPa specimen, respectively. The lower-pressure specimen exhibited a wider oxygen-affected region, whereas the higher-pressure specimen showed a steeper oxygen gradient. In the prior-β transformed layer, lath-like α structures formed under both conditions, but their spatial arrangement and orientation distribution were different. Under lower internal pressure, the laths were more regularly arranged and showed a more complete colony structure. Under higher internal pressure, the laths were more interwoven, and the orientation distribution became more scattered. Meanwhile, the high-pressure specimen retained a higher local orientation gradient and a higher degree of lattice distortion. These results indicate that the above microstructural differences mainly arise from the effect of internal pressure on the high-temperature exposure history. A higher internal pressure causes earlier instability of the specimen, thereby shortening the effective time for oxygen diffusion and microstructural evolution, rather than directly changing the oxidation or phase transformation process. Full article

Background/Objectives: Three-dimensionally (3D) printed resins are increasingly used for removable orthodontic appliances, but how their mechanical reliability changes in the oral environment is unclear. This study evaluated the effect of bio-ageing environment and material type on the biaxial flexural strength and Weibull reliability of one conventional acrylic resin (Orthocryl, OC) and two 3D-printed photopolymer resins (BioMed Clear, BMC; and KeySplint Hard, KH). The Weibull modulus (m) reflects how consistent, or predictable, the strength is among specimens, independent of its average value. Methods: Disc specimens (n = 32) were aged for 24 h at 37 °C in pooled human saliva, a Streptococcus mutans biofilm, or water, and the biaxial flexural strength was measured by the piston-on-three-balls method (1 mm/min). Data were analysed with two- and three-parameter Weibull statistics to estimate the Weibull modulus (m), characteristic strength (σ₀), strength at 5% failure probability (σ₅%), and threshold strength (σ_μ), with model selection guided by the Akaike Information Criterion. Results: Biofilm exposure lowered m while σ₀ was preserved: m fell from 9.96 (saliva) and 7.98 (water) to 1.95 for OC, and from 17.61 and 13.01 to 2.62 for BMC, whereas σ₀ stayed near 55 MPa (OC) and 64 MPa (BMC). Under biofilm the modulus of all three converged to low values (1.4–2.6), abolishing the differences among materials; OC and BMC required a three-parameter model only after biofilm (σ_u ≈ 41 MPa), whereas KH required it in every environment (σ_u = 28.9–38.7 MPa). Conclusions: Biofilm ageing mainly reduced strength predictability, while characteristic strength was largely preserved. This indicates that flexural strength alone may be insufficient to qualify resins for removable appliances, and that printed resins studied here are not inherently superior or inferior to conventional acrylic. Full article

Mass cytometers can record 40–50 parameters per single cell for millions of cells in a sample. Many methods have been developed to cluster phenotypically similar cells within cytometry data, but there are fewer methods to visualize activity and interactions of pairs of proteins across these populations. We have developed a workflow for analyzing correlations associated with predefined populations. By clustering blood samples from acute myeloid leukemia (AML) patients and normal controls using an established algorithm, we obtained a minimum spanning tree of clusters of single cells. Using surface marker expression, we identified clusters on the tree that belonged to phenotypes of interest. Next, we computed correlations between pairs of proteins in each cluster. We developed a novel, coherent, probability-based statistic to test differences between vectors of correlation coefficients. By comparing all combinations of the normal controls under the statistic, we created an empirical distribution that could provide a conservative threshold of differential correlation. Using this empirically derived distribution to define significance, we compared pooled samples from AML subtypes and normal controls to detect differential correlations. Given the structure present within this cytometry dataset, we found it natural to consider correlations in this manner versus aggregating all data and computing a single correlation. Our approach has the advantage that we can localize the statistical measure to determine contributions from particular phenotypic populations. Differentially correlated pairs of proteins can be further explored as possible testable hypotheses by considering a population’s distribution of correlation coefficients or biaxially plotting protein expressions within individual cells in a given population. Full article

Concrete-filled steel tube (CFT) columns have been widely used in high-rise buildings and bridge structures due to their excellent composite performance. In practical applications, CFT columns inevitably experience eccentric loading due to structural imperfections, asymmetric load distributions, and seismic actions, particularly in corner columns of seismic-resistant structures where biaxial eccentric compression may occur. However, despite extensive studies on the local buckling behavior of CFT columns under axial compression and uniaxial eccentric compression, the behavior under biaxial eccentric compression remains insufficiently understood. In this paper, a theoretical study on the local buckling behavior of rectangular CFT columns subjected to biaxial eccentric compression is presented. Based on classical elastic stability theory and the energy variation method, an analytical model is developed by assuming that both the loaded and unloaded edges of the steel tube are elastically restrained against rotation and selecting an appropriate deflection function satisfying the boundary conditions and compatibility requirements. The relationship of local buckling strength of rectangular CFT columns subjected to biaxial eccentric compression and width-to-thickness ratios under different stress gradient coefficients is obtained. The results indicate that the local buckling strength σ_cr of steel tubes decreases significantly with the increasing width-to-thickness ratios b/t when the stress gradient coefficient α₀₁ and α₀₂ remain unchanged, and the local buckling strength of the broad face is much lower than that of the narrow face. As the stress gradient coefficient increases, the local buckling strength σ_cr of steel tubes increases. When the stress gradient equals 0, the steel tube is subjected to axial compression and the minimum of the local buckling coefficient can be obtained. When the stress gradient equals 2, the steel tube is subjected to pure bending and the maximum of the local buckling coefficient can be obtained. The proposed model provides a rational prediction of local buckling strength under different biaxial eccentric compression conditions. Finally, recommended width-to-thickness ratio limits for steel tube plates with different steel grades and stress gradient coefficients are proposed, which can provide practical guidance for preventing premature local buckling and improving the material utilization efficiency of rectangular concrete-filled steel tube columns. Full article

Agrivoltaic (AV) systems represent a promising strategy for integrating renewable energy production and agricultural activity on the same land unit, while contributing to soil water conservation under increasingly frequent drought conditions. This preliminary, single-site case study investigates the effects of a horizontal biaxial tracking AV system on soil water dynamics in a durum wheat field in the Po Valley (Borgo Virgilio, Mantua, Italy) over a full monitoring period, covering the final crop growth stages and the post-harvest bare soil phase (May–December 2024). Monitoring of soil temperature, volumetric water content (VWC), and soil water potential (SWP) was conducted at four depths (15, 30, 45, and 60 cm) at one representative monitoring station per treatment, comparing soil under AV cover (AVC) and in unshaded conditions (UC), located 10 m apart. Paired VWC and SWP measurements were used to derive site-specific soil water characteristic curves (SWCCs) and to calibrate the agro-hydrological model CRITERIA-1D, which was used to estimate available water (AW) in the first 80 cm of depth for both treatments. Measured VWC values were higher in the AVC profile than in the UC profile at all monitored depths throughout the May–September period, with differences persisting, although at lower values through October–December. Estimated AW was consistently higher under AVC than in UC during both the dry and wet periods. Despite higher VWC, the AVC profile showed more negative average SWP values at all depths during summer. This pattern is consistent with the shape of the derived SWCCs and may point to differences in water-retaining capacity between the two profiles, possibly related to structural modifications induced by 13 years of AV system operation. These preliminary findings suggest that AV systems could potentially improve soil water availability in the root zone of rainfed cereal crops and propose the hypothesis that long-term AV cover may act as a driver of changes in soil hydraulic properties, with implications for the sustainability and climate resilience of dryland farming systems. However, given the design of this case study, with only one monitoring point per treatment, the observed differences reflect the specific monitored locations and cannot fully disentangle the AV treatment effect from pre-existing spatial heterogeneity in soil properties. The preliminary results obtained in this study should therefore not be generalised beyond the specific conditions of this case study, and the interpretations proposed here should be treated as unproven hypotheses rather than established conclusions. Further studies with spatial replication and multi-year monitoring are needed to confirm these patterns. Full article

A multi-scale framework is proposed for predicting the equivalent engineering elastic constants of carbon/glass hybrid composite laminates with different fiber volume fractions V_f by integrating multiscale finite element homogenization with analytical micromechanics. Biaxial carbon fiber fabric reinforced vinyl ester composites are used as the target material system, and representative volume element (RVE) models are constructed sequentially at the lamina, laminate, and hybrid-laminate scales. At the lamina scale, the analytical self-consistent field micromechanics (SCFM) approach and the RVE method give highly consistent predictions for the fiber-dominated longitudinal modulus E₁ and in-plane shear modulus G₁₂, with deviations below 2%. However, the SCFM approach overestimates the transverse modulus E₂ and transverse Poisson’s ratio ν₂₃ as the V_f rises. The unidirectional lamina constants predicted by SCFM and RVE are then used as inputs for an analytical solution for predicting elastic constants (ASPE) and a finite-element-analysis-based micromechanics (FEAM) model of laminate and hybrid-laminate. At the laminate scale, the moduli predicted by ASPE(SCFM) and ASPE(RVE) differ by less than 2%, whereas the out-of-plane properties are sensitive to the transverse lamina inputs. Experimental validation shows that the E_x values predicted by ASPE(RVE) and FEAM(RVE) deviate from the measured average by approximately 3.5%, with good agreement also obtained for G_xy and ν_xy. At the hybrid-laminate scale, ASPE(RVE) and FEAM(RVE) exhibit only minor differences in estimating the in-plane moduli, out-of-plane moduli, and Poisson’s ratios. Full article

Fiber Bragg gratings (FBGs) embedded in polymer composite materials is a promising method for structural health monitoring (SHM). Conventionally, FBGs are treated as axial strain sensors with a constant sensitivity coefficient, which can lead to significant measurement errors for the multi-axial stress states. This study developed a general framework to calculate the axial strain sensitivity coefficient considering the local multiaxial strain state of the host composite materials, where the analytical strain transfer principle (STP) was integrated with the Opto-mechanical model of FBGs. The responses of embedded FBGs under hydrostatic pressure, biaxial compression, and biaxial tension conditions were validated by the experimental tests. The results further reveal the strong influence of the interfacial bonding state between the FBG and host composite material on the FBG response. This study advances the embedded FBG technology in SHM for composites. Full article

This study investigates the quasi-static equalbiaxial compression behavior of 3D-printed Miura-ori metamaterials incorporating both out-of-plane and in-plane gradient configurations. The Miura-ori structure, composed of tessellated parallelogram units, exhibits pronounced anisotropic behavior due to its unique folding geometry. To assess this behavior, specimens were fabricated using ABS resin and subjected to equalbiaxial compression in three orthogonal directions: the xy-direction (in-plane compression), the yz-direction (edge-on side loading), and the xz-direction (accordion-like profile loading). In the out-of-plane gradient design, the acute angle ϕ was varied across layers, significantly influencing both yield stress and specific energy absorption (SEA). Compared with the uniform design, gradient configurations exhibited reduced mechanical performance in the xy-direction and yz-direction, and enhanced properties in the xz-direction. In addition, in-plane (x-direction) gradient structures were evaluated under xy-, yz- and xz- direction compression. The results indicate that gradient configuration specimens exhibit significantly lower yield stress and specific energy absorption than uniform structure specimens, with deformation initiating preferentially in regions with smaller acute angles and lower local stiffness. The results highlight the strong influence of geometric gradation and loading direction on the mechanical performance of Miura-ori metamaterials. This work provides new insights into the design and optimization of origami-inspired energy-absorbing structures for use in advanced mechanical, aerospace, and protective engineering applications. Full article

The elastoplastic behaviour and failure of unreinforced masonry structures under biaxial loading are critically governed by the mechanical response of brick–mortar contact interfaces. Detailed finite element micromodelling explicitly resolves these elements, offering rigorous numerical representation; however, practical implementation requires the determination of contact stiffness parameters, for which no established experimentally calibrated expressions exist. This study presents an experimental-numerical calibration methodology integrating experimental characterisation of constituent materials and small-scale masonry specimens with numerical validation, using a concrete damaged plasticity model for quasi-brittle materials and traction-separation laws for interfaces, applied to a specific ceramic masonry system. The proposed methodology provides a practical and reproducible basis for experimental calibration of the contact stiffness parameters required in the detailed micromodelling of brick–mortar interfaces. Numerical simulations reproduce experimental behaviour, with peak load predictions within ±6% for normal and ±1% for shear loading. Detailed micromodelling reveals that normal stresses develop at interfaces even under nominally pure shear, evidencing coupled normal-tangential behaviour, the key role of normal adhesive contact strength, and the justification for the cohesive–frictional interface characterisation. Full article

This article presents a complete cost-optimized design for rectangular isolated footings (RIFs) under biaxial bending with a partially compressed contact area (PCCA) and an eccentric column, i.e., part of the base is in contact with the soil (generating compression), and the other part is not in contact with the soil (generating neither compression nor tension), and the soil pressure behaves linearly. The proposed model is presented by integration to find the moments in the critical sections, the bending shears in the critical sections and the punching shear acting on the RIF, and these are compared with those that must be resisted according to the standards (ACI 318-19) Some articles show complete designs for RIFs with a fully compressed contact area (FCCA) and an eccentric column, and other articles show only the minimum area (A_min) for RIFs with a PCCA and an eccentric column. The main contributions of this article are as follows: (1) the A_min is determined from the loads and moments, assuming that the loads and moments it resists must be greater than or equal to those acting on the RIF; (2) the minimum cost (C_min) is determined. Three numerical studies are described to demonstrate the advantages of this study over other models. The results indicate that, according to the studies presented in this article, savings of up to 45.99% for A_min and 93.62% for C_min can be achieved using the model proposed in this article (MPA); this occurs when the pressure acting on the foundation does not reach the maximum available soil pressure (p_max). Therefore, this paper could be of great use to engineers dedicated to the construction of foundations. Full article

Two-dimensional (2D) intrinsic ferromagnets with perpendicular magnetic anisotropy (PMA) have been experimentally verified as promising candidates for nanoscale spintronic devices and magnetic random-access memories. In this work, we systematically investigate the stability, electronic structure, and magnetic properties of monolayer MOCl (M = Ti, V, Cr, Mo) via first-principles calculations. The results demonstrate that allshi ciju monolayers MOCl (M = Ti, V, Cr, Mo) are intrinsic ferromagnetic semiconductors, with magnetic moments of 1.0 μ_B/Ti atom, 2.0 μ_B/V atom, 2.5 μ_B/Cr atom and 3.0 μ_B/Mo atom, respectively. Notably, both monolayers TiOCl and CrOCl exhibit perpendicular magnetic anisotropic energy (MAE), which is mainly contributed by metal atoms Ti and Cr, respectively. Drawing on the second-order perturbation theory, we conduct an analysis of the density of states and the magnetic anisotropy energy (MAE) resolved by d orbitals for Ti and Cr atoms. Our analysis shows that in monolayer TiOCl, the MAE of Ti atoms mainly stems from the disparities in matrix elements between the d_yz and d_x²−y² (d_xz) orbitals. Conversely, in monolayer CrOCl, the MAE of Cr atoms is largely due to the differences in matrix elements between the d_xy (d_yz) and d_x²−y² (d_z²) orbitals. Biaxial strain can efficiently regulate the MAE of monolayer CrOCl. Specifically, when under tensile strain, the MAE of monolayer CrOCl experiences a substantial increase. Our research results indicate that both monolayers TiOCl and CrOCl have significant potential for use in spintronic devices and high-density data storage systems. Full article

Large-scale thick curved components made of high-strength steel are critical to deep-sea pressure hulls and large structural components of engineering machinery. During forming, these components experience reverse loading upon unloading, and the pronounced Bauschinger effect of high-strength steel significantly compromises springback prediction accuracy, leading to costly die iterations. Existing cyclic tension–compression and shear tests are limited to uniaxial stress states and fail to capture the mechanical behavior under in-plane biaxial cyclic loading. Herein, a cyclic four-point bending method is proposed to characterize the Bauschinger effect of Q890 steel under biaxial cyclic loading. By tailoring the width-to-thickness ratio of the specimens, a series of plane stress states with different initial plastic stress ratios were obtained, covering the dominant stress conditions encountered in forming typical large-scale double-curvature thick plates. Full-field strain evolution during cyclic bending was captured in real time via digital image correlation (DIC), enabling systematic acquisition of equivalent stress–strain curves under various biaxial stress ratios over multiple cycles. As the width-to-thickness ratio increases, both forward and reverse yielding progressively degrade: the equivalent yield strength, forward peak flow stress, and reverse yield strength drop from 1098, 1193, and 742 MPa to 934, 1065, and 685 MPa, respectively. Accordingly, the Bauschinger ratio B, Bauschinger hardening parameter BHP, and Bauschinger energy parameter BEP decrease from 0.479, 0.789, and 4.747 to 0.363, 0.655, and 2.900, respectively, revealing a strong stress-ratio dependence of the Bauschinger effect. Notably, the springback ratio also shows clear dependence on the biaxial stress ratio, loading direction, and cyclic history, indicating that in-plane biaxial stress-state effects should be considered when characterizing the Bauschinger effect and springback behavior of Q890 high-strength steel. Full article

To improve the energy absorption capacity of star-shaped honeycomb (SSH), this paper proposes a novel star-shaped negative Poisson’s ratio (NPR) structure with a second-order fractal substructure based on the principles of self-similarity and iterative generation in fractal theory. Subsequently, a fractal star-shaped honeycomb (FSSH) is developed through a biaxially symmetric design. Finite element analyses were performed, and the deformation modes, NPR effect, and energy absorption capacity of the proposed FSSH under low-velocity (5 m/s), medium-velocity (30 m/s), and high-velocity (100 m/s) dynamic compression were systematically investigated and compared with those of the SSH. Furthermore, the effect of cell wall thickness on the dynamic compressive performance of the FSSH was thoroughly analyzed. The results indicate that, at the same relative density, the FSSH exhibited greater energy absorption capacity than the SSH, although this enhancement was achieved at the expense of a reduced NPR effect. As cell wall thickness increased, the deformation mode of the FSSH became more uniform under low- and medium-velocity dynamic compression. Under medium- and high-velocity dynamic compression, the NPR effect became more pronounced at relatively low axial strains. Moreover, the energy absorption capacity was significantly improved under low-, medium-, and high-velocity dynamic compression. This study provides a novel design strategy and theoretical guidance for the development of advanced energy-absorbing metamaterials. Full article