Search Results (978)

Owing to their tunable and biocompatible characteristics, collagen- and gelatin-based hydrogels have gained attention in numerous applications, including biomedical, food, pharmaceutical, and environmental. The gelation mechanisms and resulting network structures of collagen and gelatin differ significantly depending on the presence of intra- and intermolecular crosslinks. These differences enable the tailoring of mechanical properties to achieve desired characteristics in the final product. Mechanical gel strength and elasticity determine how effectively hydrogels can mimic natural tissues and respond to deformations. Probing the rheological properties of these gels enables a deeper understanding of their structure, physical attributes, stability, and release profiles. This review provides an in-depth evaluation of the factors affecting the mechanical strength of collagen- and gelatin-based hydrogels, highlighting the influence of co-molecules and the application of physical, chemical, and mechanical treatments. Herewith, it brings insights into how to manipulate the mechanical properties of these gels to improve their end-use functionality. Full article

The mechanical performance of cast iron is strongly governed by the morphology of its graphite phase, yet establishing a quantitative link between microstructure and macroscopic properties remains a challenge. In this study, a three-dimensional finite element method (FEM)-based micromechanical framework is proposed to analyze and predict the mechanical behavior of cast iron with representative graphite morphologies, spheroidal and flake graphite. Realistic representative volume elements (RVEs) are reconstructed based on experimental microstructural characterization and literature-based X-ray computed tomography data, ensuring geometric fidelity and statistical representativeness. Cohesive zone modeling (CZM) is implemented at the graphite/matrix interface and within the graphite phase to simulate interfacial debonding and brittle fracture, respectively. Full-field simulations of plastic strain and stress evolution under uniaxial tensile loading reveal that spheroidal graphite promotes uniform deformation, delayed damage initiation, and enhanced ductility through effective stress distribution and progressive plastic flow. In contrast, flake graphite induces severe stress concentration at sharp tips, leading to early microcrack nucleation and rapid crack propagation along the flake planes, resulting in brittle-like failure. The simulated stress–strain responses and failure modes are consistent with experimental observations, validating the predictive capability of the model. This work establishes a microstructure–property relationship in multiphase alloys through a physics-informed computational approach, demonstrating the potential of FEM-based modeling as a powerful tool for performance prediction and microstructure-guided design of cast iron and other heterogeneous materials. Full article

Buildings crossing active faults often suffer severe damage due to fault dislocation during direct-type urban earthquakes. This study employs physical model tests to systematically investigate the dynamic response mechanisms of the integrated “surface rupture zone–overburden–foundation–superstructure” system subjected to bedrock dislocation. A testing apparatus capable of simulating reverse faults with adjustable dip angles (45° and 70°) was developed. Using both sand and clay as representative overburden materials, the experiments simulated the processes of surface rupture evolution, foundation deformation, and structural response under varying fault dislocation magnitudes. Results indicate that the fault rupture pattern is governed by the bedrock dislocation magnitude, soil type, and fault dip angle. The failure process can be categorized into three distinct stages: initial rupture, rupture propagation, and rupture penetration. The severity and progression of structural damage are primarily determined by the building’s location relative to the fault trace. Structures located entirely on the hanging wall exhibited tilting angles that remained below the specified code limit throughout the dislocation process, demonstrating behavior dominated by rigid-body translation. In contrast, buildings crossing the fault exceeded this limit even at low dislocation levels, developing significant tilt and strain concentration due to differential foundation settlement. The most severe damage occurred in high-angle dip sand sites, where the maximum structural tilt reached 5.5°. This research elucidates the phased evolution of seismic damage in straddle-fault structures, providing experimental evidence and theoretical support for the seismic design of buildings in near-fault regions. The principal theoretical and methodological contributions are (1) developing a systematic “fault–soil–structure” testing methodology that reveals the propagation of fault dislocation through the system; (2) clarifying the distinct failure mechanisms between straddle-fault and hanging-wall structures, providing a quantitative basis for targeted seismic design; and (3) quantifying the controlling influence of fault dip angle and soil type combinations on structural damage severity, identifying high-angle dip sand sites as the most critical scenario. Full article

The accurate prediction of the mechanical behaviour of silica–epoxy nanocomposites is essential for advancing their application in high-performance industries, including aerospace, automotive, and structural engineering. Conventional experimental characterization methods are often time-consuming and costly, highlighting the need for efficrelianceient computational alternatives. This study proposes a machine learning based on Random Forest Regression to predict the stress–strain behaviour of silica–epoxy nanocomposites with high accuracy. The model employs two independent and physically meaningful input parameters—SiO₂ nanoparticle concentration (wt%) and strain—to predict stress, thereby capturing the true constitutive relationship of the material. The model was trained and validated on an extensive experimental dataset of 7422 observations across five compositions (0–4 wt% SiO₂), obtained from systematic tensile testing following the ASTM D638 standard. Rigorous stratified 10-fold cross-validation confirmed excellent generalization (mean R² = 0.9977 ± 0.0023) with minimal overfitting (training–validation gap < 0.005). The performance of the test set (R² = 0.9948, mean absolute error (MAE) = 0.0404 MPa) surpasses recent literature benchmarks by nearly 5%, establishing state-of-the-art accuracy in nanocomposite property prediction. Error analysis revealed stable prediction accuracy throughout the elastic and plastic regimes (error variance < 0.004 MPa² for strain), with a physically consistent increase in error near failure due to complex damage mechanisms. Feature importance analysis indicated that strain and SiO₂ concentration contributed 78.4% and 21.6%, respectively, to predictive accuracy. This is consistent with constitutive modelling principles, in which deformation state primarily determines stress magnitude, while composition modulates the functional relationship. Mechanical property extraction from experimental curves showed optimal performance at 2–3 wt% SiO₂, yielding balanced enhancements in tensile strength (+1–2%) and failure strain (+36–64%) relative to neat epoxy. The validated framework reduces material development time by 65–80% and cost by 60–75% compared with conventional trial-and-error methods, offering a robust, data-driven tool for the efficient design and optimization of silica–epoxy nanocomposites. A comprehensive discussion of limitations and applicability boundaries ensures the framework’s responsible and reliable deployment in engineering practice. Full article

Explosive welding technology is crucial for the production of large-area plates composed of materials with varying plastic and physical properties. Severe plastic deformation processes increase the mechanical strength of the plates by refining grains and increasing dislocation density. The aim of the research presented in this paper was to analyze the effect of Equal Channel Angular Pressing (ECAP) on the mechanical properties and microstructure of an Al/Cu (EN AW-1050/Cu-ETP) bimetallic plate produced by the explosive welding technology. The ECAP process was carried out at room temperature. The ECAP experiments consisted of 1–3 passes using a die with a channel angle of 90°. The ram speed was 40 mm/min. The study also considered various sample cutting orientations (longitudinal, transverse) and various positions of the bimetallic sample in the die entry channel. Rotating the sample by an angle of 180° between consecutive passes was also considered. To achieve the research objective, static tensile tests, Vickers hardness tests at a load of 4.9 N, and microstructural analysis of the samples using scanning electron microscopy and energy dispersive spectroscopy were carried out. It was found that each subsequent pass in the ECAP process led to a gradual, severe change in the morphology of the Al/Cu interfacial transition layer. The orientation of the cutting plane of the samples was shown to have no effect on the hardness of the bimetallic material. Vickers hardness tests preceded by the ECAP process revealed a more uniform hardness distribution compared to the base material. The orientation of the Al/Cu plate layers in the ECAP die channel clearly influenced the character of the hardness distribution. Full article

The Eastern Sag of the Liaohe Depression, situated in the Bohai Bay Basin, represents a key area for hydrocarbon exploration in northeastern China. Despite decades of research, the mechanisms governing its complex structural evolution remain unclear, largely due to multiple tectonic reactivations associated with the Tan–Lu Fault Zone. In this study, newly acquired deep seismic reflection data were used to interpret representative structural profiles across the sag. Complementary sandbox modeling experiments were conducted to reconstruct the basin’s prototype and to verify the structural kinematics inferred from the seismic data. Integration of seismic interpretation, physical modeling, and thin-section microstructural observations of fault-related cores allowed us to establish a comprehensive Cenozoic evolutionary model of the sag. The results reveal three main tectonic evolution stages: (1) an extensional fault-depression stage during the Shahejie period, (2) a strike-slip modification phase during the Dongying period, and (3) a subsequent thermal-subsidence stage in the Guantao period. Pre-existing basement faults exerted a significant control on fault geometry, subsidence patterns, and the segmentation of four sub-sags. Moreover, transtensional and transpressional deformation during the late stages reshaped the basin architecture and fault linkage systems. These findings provide new insights into the structural evolution and controlling mechanisms of the Eastern Sag, offering valuable guidance for deep hydrocarbon exploration in the Bohai Bay Basin. Full article

Tunnel construction in karst formations faces significant geological uncertainties, which pose challenges for quantifying construction risks using traditional deterministic methods. This paper proposes a probabilistic reliability analysis framework that integrates the Stochastic Finite Element Method (SFEM), a Radial Basis Function Neural Network (RBFNN) surrogate model, and Monte Carlo Simulation (MCS) method. The probability distributions of rock mass mechanical parameters and karst geometric parameters were established based on field investigation and geophysical prospecting data. The accuracy of the finite element model was verified through existing physical model tests, with the lateral karst condition identified as the most unfavorable scenario. Limit state functions with control indices, including tunnel crown settlement, invert uplift, ground surface settlement and convergence, were defined. A high-precision surrogate model was constructed using RBFNN (average R² > 0.98), and the failure probabilities of displacement indices were quantitatively evaluated via MCS (10,000 samples). Results demonstrate that the overall failure probability of tunnel construction is 3.31%, with the highest failure probability observed for crown settlement (3.26%). Sensitivity analysis indicates that the elastic modulus of the disturbed rock mass and the clear distance between the karst cavity and the tunnel are the key parameters influencing deformation. This study provides a probabilistic risk assessment tool and a quantitative decision-making basis for tunnel construction in karst areas. Full article

EMFIT, also referred to as EMFi, is a ferroelectret film related to polyvinylidene fluoride (PVDF) sensors. It is an electroactive polymer (EAP) based on a polyolefin structure and consists of three layers of polyester film. Its application in geophysical monitoring has not been reported in the literature. At present, EMFIT is mainly employed in ballistocardiography and medical sleep monitoring, as developed by the manufacturer Emfit Ltd. (Vaajakoski, Finland). Within the multidisciplinary monitoring network of the National Institute for Earth Physics (NIEP), EMFIT is used as a pressure sensor in combination with infrasound transducers and microphones deployed in seismic areas. The primary aim of this study is to evaluate its suitability for detecting seismic noise that precedes earthquakes, generated by rock fracturing associated with crustal deformation. Although similar studies have been reported, they have not involved the use of EMFIT sensors. The novelty of this approach lies in the large surface area and mechanical flexibility of the material. Beyond seismic forecasting, the research also examines whether this type of sensor can contribute to seismic monitoring as a complement to conventional instruments such as accelerometers, seismometers, and microbarometers. Data analysis relies primarily on spectral time-series methods and incorporates measurements from other acoustic sensors (microphones and microbarometers) as well as a weather station. The working hypothesis is the potential correlation between the recorded data and the presence of enhanced noise prior to the detection of seismic waves by standard seismic sensors. The target area for this investigation is Vrancea, specifically the Vrâncioaia seismic station, where multidisciplinary monitoring includes infrasound, radon, thoron, soil temperature, and atmospheric electrical discharges. Preliminary tests suggest that the EMFIT sensor may function as a highly sensitive device, effectively serving as an “ear” for detecting ground noise. Full article

Nanoporous gold (NPG), characterized by a bicontinuous network of nanoscale solid ligaments and pore channels, exhibits exceptional physical and chemical properties. However, the limited strength and stiffness of traditional isotropic NPG (INPG) have constrained its engineering applications. To effectively enhance the mechanical properties of NPG, this work proposes an innovative anisotropic NPG (ANPG) architecture featuring unidirectional ligament orientation. By controlling spinodal decomposition parameters, ANPG models with preferentially aligned ligaments and INPG with random ligament orientation are constructed, spanning relative densities from 0.30 to 0.50. The ligament length and diameter of ANPG along the out-of-plane direction are twice those along other directions. Molecular dynamics simulations of tensile tests show that ANPG exhibits superior out-of-plane Young’s modulus and yield strength but reduced fracture strain compared to INPG. Crucially, ANPG maintains toughness comparable to INPG at relative densities below 0.4, offering an optimal strength-toughness balance for practical applications. Scaling law analysis demonstrates INPG follows classical bending-dominated Gibson-Ashby behavior, while ANPG exhibits a hybrid deformation mechanism with significant ligament stretching contribution. Atomic-scale analysis reveals that both structures develop dislocation-mediated plasticity initially, but ANPG transitions to localized ligament necking and fractures more rapidly, explaining its reduced ductility. Strain localization quantification, measured by atomic shear strain standard deviation, confirms the intensifier deformation concentration in ANPG at large plastic strain. These findings suggest anisotropic design as a powerful strategy for developing high-performance NPG for actuators, sensors, and catalytic systems where simultaneous mechanical robustness and functional performance are required. Full article

This paper introduces a novel and efficient approach for Gaussian Splatting in dynamic scenes that leverages symmetry principles for enhanced computational efficiency and visual fidelity. First, we diverge from conventional methods that process static and dynamic regions uniformly by implementing an adaptive separation mechanism. This approach exploits the inherent symmetry-breaking properties between static and dynamic Gaussian points, utilizing motion differentials to identify and isolate dynamic elements. This symmetry-aware partitioning allows for the application of specialized processing techniques to each region type, with static regions benefiting from their temporal symmetry while dynamic regions receive targeted deformation modeling. Second, through this fine-grained partitioning of static and dynamic components guided by symmetry analysis, we achieve more judicious allocation of computational resources. The symmetric treatment of spatially coherent static regions and the focused processing of symmetry-breaking dynamic elements substantially reduce memory requirements and training time while preserving reconstruction quality. This optimization effectively conserves valuable computational resources without compromising visual fidelity. Third, we introduce a sophisticated deformation modeling framework that learns the transformational characteristics of grids composed of multiple Gaussian points. By incorporating radial basis function principles, which inherently preserve local rotational and translational symmetries, our method efficiently encodes complex motion information of dynamic Gaussian points. This symmetry-preserving deformation approach not only enables high-fidelity reconstruction of dynamic regions but also significantly improves the rendering of continuously evolving shadow interactions by maintaining physical consistency. The result is a marked reduction in visual distortion and rendering outputs that demonstrate exceptional correspondence to ground truth imagery across diverse dynamic scenes. Full article

The Nonlinear Twist Extrusion (NLTE) method, a novel severe plastic deformation (SPD) technique, aims to enhance grain refinement and achieve a more uniform plastic strain distribution. Grain size and its uniform distribution strongly influence the physical properties of metals. Therefore, predicting texture evolution during processing is essential for optimizing forming parameters and improving material performance. In this study, a rate-dependent crystal plasticity formulation is implemented in an explicit framework in Abaqus finite element software, based on a finite strain approach with multiplicative decomposition of the deformation gradient. Crystal plasticity finite element (CPFEM) simulations are conducted on single-crystal copper under boundary conditions representing the NLTE process. The influence of dynamic friction coefficients on texture evolution is systematically investigated, and the results are compared with experimental observations. The study provides new insights into deformation mechanisms during NLTE and highlights the strong correlation between texture development and forming parameters. Full article

The glass-forming ability of short-chain alkanes remains a fundamental challenge in condensed matter physics. This study investigates the structural properties of n-hexane (C₆H₁₄) and decane (C₁₀H₂₂) under two distinct cooling regimes using Raman spectroscopy: fast cooling (~50–100 K/s via contact freezing on a copper substrate at 77 K) and conventional cooling (~1–5 K/s). Despite employing rapid cooling protocols, both alkanes underwent crystallization without forming amorphous phases. n-Hexane formed a defective crystalline structure characterized by broad spectral bands (FWHM ~40–45 cm⁻¹) and diffuse phase transitions in the 180–200 K range, while decane exhibited highly ordered crystalline structures with sharp spectral features (FWHM ~15–20 cm⁻¹) and abrupt transitions at 220–240 K. Quantitative analysis of characteristic Raman bands (skeletal deformations, C-C stretching, and C-H stretching vibrations) revealed fundamental differences in crystallization mechanisms related to molecular chain length. The study demonstrates that contact freezing methods are fundamentally incapable of achieving the extreme cooling rates (>10⁴ K/s) and ultra-thin film conditions (<1 μm) necessary for alkane vitrification. These findings establish spectroscopic diagnostic criteria for distinguishing between defective and well-ordered crystalline structures and define the limitations of conventional cryogenic techniques for glass formation in alkanes. Full article

Aiming at the problem that obstacle avoidance flexibility and formation integrity are difficult to coexist in multi-robot formation motion, a path-deformation mapping mechanism is proposed, which deeply integrates artificial potential field and affine transformation, and drives formation adaptive adjustment in real time through path information. By using the non-uniform scaling characteristics of the affine transformation, the limitation of traditional conformal transformation is broken through, and the unity of flexibility and integrity is realized. The effectiveness of the algorithm is verified by experiments, which provide a practical solution for cooperative obstacle avoidance of multi-robot systems in complex environments. In order to verify the performance of the algorithm, a numerical simulation is carried out, and an experimental platform composed of seven omnidirectional mobile robots is built for physical verification. The simulation and experimental results show that the formation can complete the obstacle avoidance task in the complex static obstacle environment, and the average formation tracking error is maintained below 0.05 m. Compared with the traditional local obstacle avoidance or formation switching method, this algorithm significantly improves the fluency of the obstacle avoidance process and the integrity of the formation while ensuring a success rate of 100% obstacle avoidance. Full article

The hardening soil model with small-strain stiffness (HSS model), capturing nonlinear stiffness of soils at small strains, offers advantages for deformation analysis of tunnels or deep excavations in soft clay areas such as Hangzhou City. However, its complex parameters are rarely determinable via conventional tests, and regional geological differences render parameter determination methods of other areas inapplicable to Hangzhou. To address this issue, this paper summarizes the geological genesis, spatial distribution, and physical–mechanical properties of Hangzhou soft clays, and clarifies significance and acquisition of HSS model parameters. Via statistical analysis of existing literature data, the relationships between key HSS model parameters and physical indices (e.g., void ratio) were established. A 3D finite element (FE) simulation of a Hangzhou excavation validated the proposed parameter determination method: simulated lateral retaining structure displacement and surface settlement closely matched field measurements. The simulation results employing the model parameters proposed herein are closer to the measurements than those based on the method of Shanghai, providing guidance for excavation design and geotechnical parameter selection in Hangzhou soft soil region. Full article

In this study, we investigated the hot deformation behavior and microstructural evolution of a novel high-magnesium-content (high-Mg) aluminum alloy, bridging the disciplines of material processing and physical metallurgy. Uniaxial hot compression tests were performed over the temperature range of 280~400 °C and strain rates of 0.001~10 s⁻¹ to investigate its hot deformation behavior. The flow stress curves were systematically analyzed, and a constitutive model was developed to describe the thermo-mechanical response of the alloy. Microstructural evolution was characterized using scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The results indicate that dynamic recovery serves as the dominant softening mechanism at lower deformation temperatures (≤320 °C). As the temperature increased to 400 °C, a significant rise in dynamic recrystallization was observed. Moreover, at 400 °C, higher strain rates led to the formation of abundant, network-like, mushroom-shaped dynamically recrystallized grains. Full article