Search Results (5,913)

High-resolution contact localization and three-axis force estimation are crucial for human–robot interaction and precision manipulation, yet the sensing area is limited by channel density and wiring cost. Sparse strain readout makes joint estimation of location and three-axis force challenging due to cross-axis coupling and nonlinear responses, while dense arrays or extensive calibration increase complexity. We present a sparse strain-node tactile interface device (SSTID) whose three-module layout is optimized via particle swarm optimization to maximize informative response overlap, enabling contact localization (x,y) and three-axis force (F_x,F_y,F_z) estimation using only nine strain channels. We further propose a strain-node contact-state decoding framework (SCDF) implemented with a lightweight multilayer perceptron and trained via a two-stage sim-to-real strategy, including FEM pretraining followed by few-shot real-data adaptation. Experiments demonstrate accurate contact-state decoding with full-workspace characterization, supporting low-cost and scalable deployment of sparse tactile interfaces. Full article

This paper investigates the prediction of the depth of penetration (DOP) for concrete targets under high-speed projectile impact using multiple simulation algorithms in LS-DYNA. Three numerical methods, i.e., the traditional finite element method (FEM), a fixed-coupling FEM-SPH (Smooth Particle Hydrodynamics) model, and an adaptive coupling FEM-SPH model, are employed to simulate the penetration processes. The computational results are compared against established empirical formulas to evaluate their predictive accuracy and efficiency. The findings indicate a distinct trade-off between numerical precision and computational cost. The adaptive FEM-SPH algorithm achieves the highest accuracy, with a maximum error of less than 10% across considered velocity ranges, and effectively captures cavity expansion effects. The standard FEM algorithm offers the highest computational efficiency, requiring less than half the time of the other methods, albeit with a maximum error of up to 25%. The fixed-coupling FEM-SPH model provides an intermediate solution, showing improved accuracy at velocities above 400 m/s but lower efficiency. This comparative analysis offers a practical guideline for selecting appropriate simulation techniques in protective structure design, balancing the demands for rapid estimation, detailed physical insight, and final safety verification. Full article

Superconducting electrodynamic suspension (EDS) maglev technology has strong potential for ultra-high-speed transportation, with advantages such as self-stability and a large suspension gap. The magneto-electric force relationship between the onboard superconducting magnet and figure-eight null-flux coils is the key to improving system performance. This article shows a novel study on the impact of the shape of null-flux coils on the superconducting EDS maglev system, which has not been systematically studied before. A 3D model of the suspension system of EDS maglev was built using the finite element method (FEM) to study the impact of the null-flux coils’ shape. The electromagnetic forces generated by the system were calculated and compared with those in the literature to validate the model. The results showed that rectangular and circular coils displayed different influences on the components of the electromagnetic force. New results and analysis from the article show that the null-flux coil shape is a promising option for system performance optimization and can provide a theoretical basis for future improvements to the high-speed EDS maglev system. Full article

Hopper scales are critical dynamic metering equipment in industrial production, yet their metrological performance is often compromised by wear on weighing units over long-term service. This study proposes a wear state assessment method based on the evolution of vibration features. Focusing on the rocker-column weighing unit, we analyzed the mechanism by which geometric changes in the spherical indenter—caused by fretting wear—alter the system’s constraint state. A global-to-local coupled Discrete Element Method and Finite Element Method (DEM–FEM) model was constructed to account for material-structure interactions, alongside a dynamic simulation model considering wear evolution. The simulation accuracy was validated through a dedicated experimental platform. The results indicate that as spherical wear intensifies, the low-frequency swaying of the indenter is suppressed, causing the system’s vibration mode to transition from a flexible, swaying-dominated state to a high-frequency, rigid-impact-dominated state. In the frequency domain, this manifests as energy migration, characterized by attenuation of the low-frequency main peak and an elevation of the high-frequency broadband noise floor. Crucially, as a key innovation for wear diagnosis, this study reveals the directional sensitivity of statistical indicators. While the Root Mean Square (RMS) exhibits a non-monotonic V-shaped trend, the Kurtosis and Margin factors of the tangential vibration demonstrate superior monotonic sensitivity. Under severe wear conditions, these two indicators increase by 14 and 11 times, respectively. These findings provide highly effective diagnostic criteria and hold significant engineering application value for the predictive maintenance of industrial dynamic weighing systems. Full article

Access to internal fields such as stress, temperature, and fatigue indicators is essential for condition monitoring, yet direct sensing is often impractical. Finite element method (FEM)-based virtual sensors address this gap by combining sparse measurements with physics-based models. This work compares two virtual sensor workflows. The live FEM approach executes a model on demand and provides high-fidelity estimates at the cost of multi-second runtimes. The lookup database approach shifts computation offline by precomputing responses and answering online queries by fast interpolation. We introduce a quantitative cost model that links measured runtime scaling, offline construction effort, and online latency to deployment choices. The cost model is evaluated through timing studies, accuracy assessments, and an empirical break-even analysis relating offline effort to the expected number of online queries. Two case studies illustrate the method, a nonlinear tension-bar benchmark and a steady-state thermal model of a CPU die. Live FEM runtime follows a power law with $\alpha \approx 1.2$ for the tensile case and an effective $\alpha \approx 0.66$ for the CPU case due to dominant overheads. The resulting rules translate accuracy targets and latency budgets into workflow-selection criteria that support integration into digital-twin and monitoring pipelines. Full article

Functionally graded materials (FGMs) are widely applied in spacecraft structural design, thermal protection systems, and planetary landing mechanisms, benefiting from their ability to resist large thermal, pressure, and force gradients. To assess structural response behaviors for lander missions, docking maneuvers, and force transfer in layered aerospace structures, analyzing the contacts subjected to heavily stressed areas becomes very important. This article investigates the receding contact between a functionally graded top layer and a uniform substrate lying on a Winkler elastic foundation using the elasticity theory. An analytical approach has been validated using a finite element method (FEM) implemented in ANSYS. Comparison between the analytical solution and the FEM solution has been conducted for different stamp radii, elastic foundation stiffnesses, and ratios of shearing modulus for various realistic materials in the aerospace field. The data indicate very good convergence between the two solutions for both the length of contacts and the normal stress distribution, where differences are always below 3%. An increase in stamp radius leads to an extension of the contacts as well as a reduction in normal stresses and elevated stiffness and shearing modulus ratio contribute to smaller contacts and higher stresses. The validated methodological approach offers a realistic means for predicting force transfer mechanisms in spacecraft landing pads, multi-layer insulation panels, adaptive space structures, and functionally graded parts subjected to localized loads. This work offers predictive capabilities for space material interface design and optimization for harsh mechanical environments. Full article

An increased interest in decreasing the environmental impact of the construction sector and in vertical urbanization has renewed attention to timber as a primary structural material in multi-story buildings. This study investigated whether an existing 10-story reinforced concrete (RC) residential building can be redesigned as an equivalent mass-timber structure while satisfying the same structural performance requirements. It addressed the lack of like-for-like building-scale comparisons that redesigned an existing multi-story RC residential building into a functionally equivalent mass-timber scheme. A real RC building in Gävle, Sweden, was modeled, analyzed, and designed using StruSoft FEM-Design software in accordance with the Eurocodes and the Swedish National Annex, after which all main structural elements were systematically replaced with timber. Through iterative adjustments of member sizes, support conditions, and added reinforcing elements, both the RC and timber schemes were verified with respect to load-bearing capacity, serviceability, and global stability under identical load combinations. The RC and timber buildings reached maximum utilization ratios of 99% and 98%, respectively; displacements were higher in the timber building but remained within serviceability limits, and both systems were classified as globally stable. The timber alternative reduced the total structural weight to about 19% of the RC building and roughly halved the maximum vertical reaction forces, at the expense of additional beams, columns, and basement wall segments. Moreover, this article developed an equivalent-design methodology for material substitution, a bottom-up reinforcing elements logic that resolved serviceability and stability constraints in tall timber, and a performance trade-off map based on structural performance, offering guidance for future mass-timber design. Full article

In precision machining, the feed system is a critical subsystem. However, it can generate considerable frictional heat during operation, causing the temperature of the ball screw feed system to rise and resulting in thermal expansion of the ball screw. This thermal expansion reduces the machining accuracy of the final parts. To detect and compensate for the temperature and thermal error of the ball screw feed system in real time, rapidly assessing its temperature field is essential. Traditional methods such as the finite element method (FEM) provide high computational accuracy and have been extensively studied. However, their long computation process limits their application in real-time thermal error prediction. To address this, a feed drive superposition method (FDSM) is proposed herein to rapidly compute the temperature and thermal error of the ball screw feed system using the superposition principle. The FEM model divides the screw into 108 elements, each 10 mm long. The resulting temperature rise data for each element under each boundary condition are stored to form a screw temperature rise database. In practice, the actual machining conditions determine the boundary condition values. The corresponding temperature rise data are retrieved and superimposed to compute the complete screw temperature rise and thermal error. Crucially, the FDSM reduces the computation time from hours to less than 2 s—achieving an acceleration of over 3600-fold—while maintaining high accuracy. Across all three cases, the RMSE between the FDSM and FEM results is consistently below 1.2 μm, while comparison with experimental data yields an RMSE of 6.0 μm, demonstrating both its reliability and suitability for real-time thermal error compensation in ball screw feed systems. Full article

This study numerically investigates the piezoelectric behavior of a hydrofoil under vortex-induced excitation. The fluid field, characterized by a Kármán vortex street forming around the hydrofoil, is solved using the finite volume method (FVM) based on viscous flow theory. The resulting vortex-induced pressure is then imported to compute the electric field by solving a coupled electromechanical problem within the finite element method (FEM) framework, which links the electric and strain fields. The temporal and spatial distribution of the voltage under the periodic excitation force is provided, and the affecting factors, including the attack angle and the flow velocity, are analyzed in detail. Full article

The expansion of urban rail transit has exacerbated environmental issues related to low-frequency noise (LFN), yet the impact of geometric symmetry breaking on structure-borne noise remains underexplored. This study aims to quantify the mechanism by which cross-sectional asymmetry influences the vibro-acoustic coupling of viaducts. A 2.5D Hybrid Finite Element-Boundary Element Method (FEM-BEM) was employed to model a parametric box girder under eccentric track loading, and the numerical framework was validated against analytical benchmarks. The “Modal Symmetry Index” (MSI) and “Acoustic Asymmetry Indicator” (AAI) were defined to evaluate the effects of the asymmetry parameter ($\alpha$) on sound field distribution. Numerical results reveal a nonlinear “V-shaped” relationship between geometric asymmetry and acoustic directivity. While severe asymmetry ($\alpha >0.15$) exacerbates noise deflection via flexural–torsional coupling, a critical “self-balance zone” exists. Specifically, moderate asymmetry ($\alpha \approx 0.07$) effectively neutralizes load eccentricity, reducing the AAI from 1.5 dB (in strictly symmetric designs) to nearly 0 dB. Robustness analysis under right-side loading conditions further confirms a “reverse deflection” phenomenon, verifying that the proposed self-balance design minimizes directional sensitivity. These findings challenge the traditional assumption that geometric symmetry is acoustically optimal. A “competition–compensation” mechanism is identified, suggesting that deliberate, slight geometric asymmetry can serve as an effective passive noise control strategy for viaducts. Full article

This research investigates the dynamic response of three-dimensional concrete beams with coated aggregates subjected to transient wave propagation induced by piezoelectric actuators (PZT-lead zirconate titanate). The aim was to assess the effects of coated aggregates on concrete’s damping behavior and wave attenuation. The effect of various coating materials (epoxy and rubber) and replacement levels ranging from 5% to 25% by volume of the natural coarse aggregates on wave attenuation and energy dissipation were investigated through Finite Element Modeling (FEM) using Abaqus/CAE 6.14-1 software. Moreover, the effect of coating thickness is investigated for thicknesses ranging from 1.0 mm to 3.5 mm. The findings show that the replacement level, coating thickness, and coating material have a major effect on damping characteristics of concrete. It was also observed that rubber-coated aggregates with a 3.0 mm coating thickness (20% replacement level) exhibited an optimal damping ratio of 6.15%, representing a 29.5% increase, and offer enhanced energy dissipation, better damping performance, and the ability to alter wave travel paths, all of which could be advantageous for Structural Health Monitoring (SHM) applications. In line with this, the damping ratio of concrete beam models with epoxy- and rubber-coated aggregates, embedded with PZT material, was significantly higher (by approximately 1% to 18%) compared to that of the concrete model without PZT materials. Additionally, the findings showed that the concrete’s damping properties were greatly impacted by the interaction between PZT materials and coated aggregates. All things considered, the dynamic response and damping performance of concrete with coated-aggregate surface properties were successfully assessed using PZT-based simulations. Full article

This article presents a systematic synthesis of variationally grounded approaches for the design and optimization of mining structural infrastructure. This study is motivated by the critical need to ensure stiffness, reliability, and operational availability under severe loading, mass constraints, and aggressive environmental conditions. Methodologically, the study situates structural modeling and synthesis within the continuity of the principle of stationary action. It demonstrates that, in the quasi-static regime, structural equilibrium is obtained as the stationarity of the total potential energy; consequently, the finite element method (FEM) arises naturally as a Ritz–Galerkin approximation of this underlying variational statement. On this basis, topology optimization is interpreted as a physics-constrained optimization problem wherein the design is posed as an outer optimality level acting over an energetically defined state. It is worth noting that SIMP-based formulations require explicit regularization to define the effective problem being solved. Emphasis is placed on the traceability between physical assumptions, discretization choices, regularization, and the resulting structural interpretations. The core contribution of this paper is a systematic literature review that consolidates evidence across variational mechanics, FEM-based optimization, and industrial applications, identifying recurrent methodological patterns and gaps that currently limit transfer to mining practice. Furthermore, a fully specified illustrative case is included to demonstrate reporting discipline and methodological consistency, rather than as a validation of a new optimization method. The conclusions highlight that a variational reading provides a coherent theoretical backbone for structural analysis, synthesis, simulation, and physics-based digital twins, while also clarifying the extensions required for industrial deployment, such as stability constraints, manufacturability, and multiphysics coupling within Mining 4.0 workflows. Full article

As a critical aerospace structural material, the fatigue crack propagation behavior and fatigue life of the nickel-based GH4169 superalloy are directly related to the service safety of engineering components. The crack closure effect is one of the key factors influencing the fatigue life of metallic materials. At present, the finite element method (FEM) is widely used to investigate fatigue crack propagation in metals. However, the commercial software ABAQUS 2021b employs the conventional Paris law for crack growth simulation, which neglects the influence of crack closure. In addition, ABAQUS cannot simultaneously perform fatigue life prediction and crack path prediction within a single numerical model. To overcome these limitations, the bi-prism-based single-lens (BSL) three-dimensional digital image correlation (3D DIC) technique was employed to experimentally investigate the crack closure behavior during fatigue crack propagation in GH4169 compact tension (CT) specimens. A new parameter, termed the crack opening ratio (COR), was introduced to quantitatively characterize the crack closure effect. Furthermore, a self-developed plugin was implemented on the ABAQUS platform through secondary development, enabling the numerical model to incorporate the influence of crack closure during fatigue crack propagation. The plugin automatically records the crack tip coordinates at each propagation step, calculates the stress intensity factors near the crack tip, and predicts the corresponding fatigue life, thereby integrating crack path prediction and fatigue life prediction within a unified framework. The results demonstrate that the COR effectively characterizes the crack closure effect in the numerical model, and the predicted fatigue life agrees with experimental results within an 11% deviation once the crack reaches a certain length. Full article

Existing macroscopic finite element models for electron beam welding (EBW) typically assume isotropic material behavior, often failing to accurately predict residual stresses induced by strong crystallographic textures. To address this limitation, this study established a sequential dual-scale coupled numerical model bridging micro-texture to macro-mechanics by combining the crystal plasticity finite element method (CPFEM) with thermal-elastic-plastic theory. Representative volume elements (RVEs) incorporating α and β dual-phase characteristics were constructed based on electron backscatter diffraction (EBSD) data from the TA15 weld cross-section. Through simulated tensile and shear calculations on the RVEs, homogenized orthotropic stiffness matrices and Hill yield constitutive parameters were derived and mapped onto the macroscopic model. Simulation results indicate that the proposed model maintains the prediction error for molten pool morphology within 16.3%, while effectively correcting the stress overestimation inherent in isotropic models. Specifically, it adjusts the peak longitudinal residual stress at the weld center from 800 MPa to approximately 350 MPa, significantly reducing the anomalous “M-shaped” stress distribution. By successfully capturing shear stress components, this work provides a high-fidelity computational approach for predicting complex stress states in welded joints, offering critical insights for structural integrity assessment. Full article

AlSi7Mg0.6 aluminum alloy is widely adopted in many industrial fields due to its favorable mechanical properties and lightweight merits. In the catenary system of high-speed railways, AlSi7Mg0.6 aluminum alloy is adopted as the substrate of the positioning hook and positioning support, which exhibit abnormal wear in some railways. Thus, it is very important to reveal the underlying wear characteristics and discover the key factors involved. In this study, the influences of displacement (0.5 mm, 1.5 mm, and 3.0 mm) and applied load (20 N, 50 N, 100 N, and 200 N) on the wear performance of AlSi7Mg0.6 aluminum alloy are investigated experimentally and numerically. Wear experiments are time-consuming and costly, but the finite element method (FEM) can effectively solve this problem. A UMESHMOTION user-defined subroutine integrated with an ABAQUS Arbitrary Lagrangian–Eulerian (ALE) adaptive mesh technique was developed to simulate the wear evolution process of the aluminum alloy under varying displacements and applied loads. The results indicate that the wear evolution process of AlSi7Mg0.6 aluminum alloy can be effectively simulated using the UMESHMOTION subroutine. The maximum wear depth (MWD) from the FEM deviates from the experimental results by no more than 10%, and the deviation is smaller than the experimental values. The largest deviation occurs when the displacement is 3.0 mm and the applied load is 100 N, where the discrepancy reaches 7.53%. The wear volume (WV) obtained from the FEM shows a deviation of less than 20% compared to experimental results. For the case with a displacement of 0.5 mm, the numerical results underestimate the wear volume, while for the case with displacements of 1.5 mm and 3.0 mm, the numerical results overestimate the wear volume. The largest deviation in this case occurs for the case with a displacement of 3.0 mm and applied loading of 100 N, with a discrepancy of 16.33%. Full article