Search Results (2,149)

This paper proposes a split-tooth bidirectional field modulation permanent magnet (PM) motor (ST-BFMPMM) for low-speed, high-torque, direct-drive applications. Featuring a compact single-stator, single-rotor configuration with a tangentially magnetized split-tooth stator and a consequent-pole rotor incorporating radially magnetized PMs, the proposed topology realizes bidirectional field modulation to enhance the utilization of torque-producing harmonics while reducing the total PM requirement. Three pole–slot configurations (12s14p, 12s17p, and 12s19p) are optimized using finite element analysis (FEA), and the 12s19p design exhibits the best overall performance. Compared with the conventional 12s17p benchmark, its rated torque increases by 51.93%, PM consumption decreases by 39.4%, and torque ripple is reduced to 2.57%. It also achieves a 55.9% higher fundamental back-EMF and 2.51 times the torque output per unit PM area, while maintaining nearly the same calculated rated efficiency (96.88% versus 96.87%). Although the higher fundamental back-EMF causes the proposed motor to enter voltage-limited operation at a lower speed, thereby limiting its high-speed torque capability, the proposed motor provides high torque output and improved PM utilization in the targeted low-speed range, making it a promising candidate for gearless direct-drive wind turbines and heavy agricultural machinery. Full article

Traditional bone plates provide reliable fracture fixation; however, their high stiffness can cause stress shielding, thereby reducing mechanical stimulation of the bone tissue and slowing its regeneration. The biomechanical performance of a titanium plate with a localized porous structure for osteosynthesis of the radial shaft was investigated in this study. Three designs were considered: a solid plate and two plates with localized porous regions measuring 10 × 10 mm and 10 × 15 mm. The finite element analysis of the bone–plate system was performed using MSC Patran/Nastran, with rigid fixation of the proximal end of the bone and sequential application of an axial compressive load of 100 N, bending, and torsion with a moment of 1 N·m. Biomechanical performance was evaluated based on von Mises equivalent stress, fragment displacement (FD), interfragmentary movement (IFM), interfragmentary strain (IFS), and strain energy density (SED). To confirm the manufacturability of the design, the plate was fabricated from Ti–6Al–4V alloy using laser powder bed fusion (LPBF), and the geometry of the porous structure was verified by scanning electron microscopy. The results showed that the localized porous structure altered the load distribution between the plate and the bone, resulting in an increase in local stresses in the bone under the investigated loading conditions. These changes indicate an alteration in the mechanical environment within the bone, which may potentially affect conditions related to fracture healing. Among the investigated configurations, the plate with a 10 × 10 mm porous insert demonstrated the most balanced mechanical characteristics in terms of stresses in the implant, stress distribution in the bone, and structural stability. Full article

This study investigates the hybrid squeeze–flow damping characteristics of a previously developed magnetorheological (MR) mount, which integrates two vertically symmetric squeeze gaps and four flow channels. Based on the magnetic-circuit configuration, a damping-force prediction model was established specifically for the proposed hybrid structure. Magnetostatic finite element analysis (FEA) was conducted to compare the magnetic field characteristics under co-directional and opposite-direction coil excitation, and the influence of magnetic isolation components on the magnetic field distribution was additionally investigated. The results indicate that co-directional current excitation generates higher magnetic flux density in both the squeeze gaps and flow channels, enabling the magnetorheological fluid (MRF) to approach magnetic saturation at an excitation current of 2 A. The magnetic isolation components further improve the magnetic flux distribution and enhance the magnetic flux density in the squeeze gaps and flow channels. A one-way coupled numerical method combining magnetostatic FEA and computational fluid dynamics (CFD) was employed. The rheological properties of the MRF were derived from the magnetic flux density and incorporated into the CFD model via a user-defined function (UDF) to calculate the pressure losses and predict the damping force of the MR mount. The proposed model was experimentally validated over an excitation frequency range of 5–30 Hz at an amplitude of 0.15 mm, showing good agreement with the experimental results under most operating conditions. Beyond the experimentally validated range, the model was further employed to investigate the predicted damping characteristics under extended excitation conditions. The extrapolated numerical results indicate that the total damping force can reach 958.2512 N at an excitation amplitude of 0.3 mm and a frequency of 200 Hz. This result should be regarded as a model-based prediction rather than experimentally validated high-frequency performance. The squeeze mode provides the dominant damping contribution, while the contribution of the flow mode becomes increasingly significant with increasing excitation frequency. The results provide a basis for evaluating the potential of the hybrid squeeze–flow MR mount for vehicle engine vibration isolation. Full article

High-frequency induction hardening enhances the surface wear resistance and contact fatigue life of high-speed linear guides, but simultaneously produces an inhomogeneous, layered cross-sectional structure comprising a high-strength, low-ductility outer hardened layer and a low-strength, high-ductility inner core. This structural heterogeneity renders conventional straightening stroke prediction models—predicated on homogeneous material assumptions—fundamentally inadequate. Moreover, the iterative trial-bending operations ubiquitous in industrial practice progressively accumulate plastic strain, causing guide rails to exhibit erratic positive-to-negative deflection reversal during sequential straightening passes. To address these critical challenges, this study proposes a novel two-stage hybrid straightening strategy based on inverse finite element analysis (FEA) and closed-loop experimental feedback. An equivalent hardened layer depth (HD₀) is introduced as a parametric descriptor to construct a layered elastoplastic finite element model, and an inverse simulation strategy is developed to generate a comprehensive three-dimensional stroke–residual deflection prediction dataset encompassing both vertical and lateral straightening conditions across multiple support spans. Displacement-controlled three-point bending experiments validate the layered model and elucidate the mechanism by which cumulative plasticity progressively amplifies cross-sectional plastic sensitivity under repeated loading. Grounded in this physical insight, a hybrid straightening algorithm is formulated, combining dataset-driven initial stroke prediction for rapid large-deformation elimination with an upper-bound constraint and a measurement-feedback-driven sequential reduction compensation scheme for fine-tuning. Comparative experiments demonstrate that the proposed strategy effectively suppresses the oscillatory over-straightening characteristic of conventional empirical trial-and-error approaches, consistently reducing residual deflection below 0.05 mm within two to three loading cycles. This work bridges the gap between theoretical simulation and the complex physical state of actual machining, substantially improving both the efficiency and precision of straightening for guide rails with induction-hardened layers. Full article

Magnetically coupled resonant wireless power transmission (MCR-WPT) is an ideal solution for underwater wireless power transmission (UWPT). However, due to the conductivity of seawater, eddy current loss significantly reduces system transmission efficiency. This study develops an analytical estimation method to derive explicit expressions for eddy current loss and transmission efficiency, characterize their dependence on key parameters, and analyze the resonance frequency characteristics of the MCR-WPT system under different conductivities. The optimal resonant frequency and transmission efficiency improvement under variable-conductivity underwater environments are investigated. First, the coil model is simplified to its equivalent form. Based on the Biot–Savart law, the magnetic field is calculated by integral operations, and an analytical model of the eddy current loss is formulated. Consequently, the expression for the system transmission efficiency in seawater at different depths is derived, and a specific resonance frequency is identified at which the efficiency attains its maximum value. An underwater coil model is established using Ansys Maxwell finite element analysis (FEA), and the effects of electrical conductivity and resonance frequency on eddy current loss and system efficiency are analyzed. Finally, an underwater experimental platform is constructed. A freshwater solution and seawater solutions with varying electrical conductivities are prepared using artificial sea salt and pure water; frequency-sweeping experiments are then conducted. The experimental results are in good agreement with the theoretical analysis and simulations, thereby validating the accuracy of the proposed model. Full article

The conventional fabrication of concrete block moulds is characterised by persistent challenges related to standardisation, protracted redesign processes, and an absence of structural validation, all of which undermine regulatory compliance. This study proposes a standardised parametric modelling process aimed at ensuring compliance with the technical criteria of the INEN-3066 and ASTM C90 standards. An integrative methodology combining QFD/VOC matrices with CAD-CAE tools was used to parameterise three commercial mould configurations (10, 15, and 20 cm) in SolidWorks 2023. A finite element analysis (FEA) was subsequently conducted in ANSYS 2025 R1 under iterative overloads of up to 10,000 N, complemented by a rheological analysis in SolidWorks Plastics. The results show that the “male” (punch) components exhibit consistently high stiffness, maintaining fatigue safety factors above 1.61 across all three configurations. In contrast, the “female” (die) components are the more vulnerable link in the assembly: the fatigue safety factor of the 10 cm die drops below the required threshold of 1.0 at 4000 N, compared with 6175.6 N and 9254 N for the 15 and 20 cm configurations, respectively. The rheological analysis further confirmed the feasibility of an ultrafast injection cycle, with cavity filling times below 0.11 s and injection pressures ranging from 6.105 to 12.9 MPa across all formats. It is posited that, in accordance with the parametric model, a reinforced-wall geometry should be adopted for the 10 cm die, characterised by an augmentation of wall thickness by 15% and enlarged fillet radii. This is projected to elevate its fatigue-critical load beyond 4500 N without necessitating any alteration in the external block dimensions. These findings indicate that parametric CAD-CAE-CFD digitalisation can anticipate structural failures before manufacturing, offering a computational pathway toward regulatory compliance that should be confirmed through physical prototype testing. Full article

Porous Ti-6Al-4V lattice implants combine high specific strength, osseointegrative porosity, and compatibility with additive manufacturing, but conventional stiffness tuning through porosity, pore size, or unit-cell topology compromises biological pore requirements. This study presents a computational design framework in which structural kurtosis, the normalized interlayer offset between neighboring layers of a periodic cubic lattice, regulates elastic response at fixed global porosity. Closed-form expressions for the effective modulus are derived from first principles: the aligned configuration from the axial load-bearing area fraction, and the interlayer-shifted configuration from Euler–Bernoulli beam theory for guided-end connecting members. The derivations reproduce the Gibson–Ashby exponents n = 1 and n = 2, replacing the previously asserted power law, and a calibrated one-parameter interpolation bridges intermediate offsets. At 65% porosity, the effective modulus falls from 16.5 GPa in the aligned lattice to 2.64 GPa in the shifted lattice. A local-yield analysis based on peak bending curvature gives recoverable elastic strains of 1.37% at 89% porosity and 0.68% at 65%; the compliance-based values of 20.5% and 5.12% are kinematic upper bounds that neglect plastic hinging. A prefactor-free benchmark shows that obtaining the same 6.25-fold reduction by increased porosity alone would require 85.9–94.4% porosity and 0.17–0.28 mm struts, outside the osseointegration window and the resolution of selective laser melting. A GAN-CAD-FEA workflow reproduced the analytical moduli to within 7% across six design cases. All results are analytical and numerical; no specimens were fabricated or tested, and experimental validation remains required. Full article

The current study investigated the impact of facial three-dimensional shape geometry and respirator-face interface mechanics on the fit of N95 respirators in 21 Hong Kong Chinese adults. Three-dimensional facial scanning, quantitative fit testing of four N95 respirators (3M 1860, 1870+, 9105, and 9502+), and facial dimensions extraction using Geomagic Wrap were conducted in this study. The seven fit test exercises were performed in the current investigation, while finite element analysis (FEA) was used for studying respirator-face contact mechanics in a stratified subset of 14 participants wearing 3M 1870+ geometry. Among all evaluated models, 3M 1870+ had the highest pass rate. Pearson correlation analysis showed only nominal, uncorrected associations between the fit factor and nose length (r = 0.574, p = 0.007) as well as neck circumference (r = 0.434, p = 0.050). None of the anthropometric correlations remained statistically significant after Bonferroni correction for multiple comparisons (n = 38) (adjusted alpha level = 0.00132). Threshold post hoc observations of the bitragion coronal arc, neck circumference, nose height and nose length should therefore be considered as hypothesis generation and not as screening criteria. Fit factors decreased in dynamic movements, especially when bending. FEA-predicted contact area correlated strongly with experimental fit factor (r = 0.974, 95% CI: 0.918 to 0.992, p < 0.001), thus confirming the association of simulation and fit performance measurement but not serving as independent validation of the model. These preliminary results could be helpful for future respirator fit studies and respirator design for Hong Kong Chinese adults. Full article

The aim of this in vitro study is to evaluate the stress distribution of different definitive restorative materials designed with different connector dimensions using finite element analysis. Two adjacent prepared maxillary molars were designed digitally. Two-unit splinted fixed dental prostheses (FDPs) were designed with 4 different triangular connector dimensions (2 × 3, 3 × 3, 3 × 4, and 4 × 4 mm (width × length)). The tested materials are Gold Metal, Base Metal Alloy, Feldspathic Porcelain, Lithium Disilicate, Zirconia, and Zirconia-Reinforced Lithium Silicate. A total of 56 two-unit splinted crowns models were designed and evaluated using finite element analysis (FEA) in Autodesk Fusion 360. FEA demonstrated a non-linear relationship between connector size and performance, with the 3 × 4 mm design exhibiting optimal stress distribution and the highest safety factor. Among different materials, the base metal alloy showed the highest safety factor across all configurations, while zirconia and lithium disilicate performed comparably under static loading. The 3 × 4 mm connector demonstrated optimal performance across all tested materials. Base metal alloy exhibited the highest safety factor among all connector dimensions. Full article

The mechanical compatibility between dental restorative materials and the natural tooth structure is a relevant factor for long-term clinical performance. Although zirconia (yttria-stabilized tetragonal zirconia polycrystal, Y-TZP) and lithium disilicate are widely used for full-coverage crowns, their biomechanical interaction with the underlying dentin and pulp under functional loading remains insufficiently characterized. This study reports a comparative finite element analysis (FEA) of a mandibular first molar under vertical (200 N, axial) and oblique (200 N, 30°) loading, evaluating three configurations: an intact healthy tooth, a zirconia Y-TZP full-coverage crown, and a lithium disilicate full-coverage crown. The three-dimensional geometry was obtained from a cone-beam computed tomography (CBCT) study of a caries-free mandibular first molar, previously described and verified by the present group, and was analyzed in ANSYS Workbench (Static Structural). Von Mises equivalent stress, maximum principal stress and total deformation were obtained for enamel or restoration, dentin, and pulp in each configuration. Zirconia produced the highest stress concentrations in the coronal restoration (88.4 MPa vertical; 174.5 MPa oblique), exceeding the healthy enamel baseline by 57.6% and 89.7%, respectively. Both restorative materials reduced dentin stress relative to the healthy tooth, consistent with the stress-shielding effect driven by elastic-modulus mismatch. Under oblique loading, the maximum principal stress in healthy enamel reached 61.7 MPa, approaching or exceeding the upper bound of the reported tensile strength range (~10–40 MPa) and identifying oblique loading as the more demanding of the two conditions analyzed. Within the limitations of the present finite element model, lithium disilicate demonstrated a more favorable stress distribution, with dentin stress values closer to the intact-tooth baseline. The model does not include a luting cement layer, a periodontal ligament, the dentin–enamel junction, anisotropic tissue behavior or cyclic loading, and no experimental validation was performed; the results are therefore presented as a controlled numerical comparison between three configurations under the specific conditions simulated, and not as direct clinical selection criteria. Full article

This study develops a finite element analysis (FEA) framework to quantify hydrostatic consolidation of ultra-high-molecular-weight polyethylene (UHMWPE) fibril arrays containing interstitial voids. Hexagonal and stochastic representative volume elements (RVEs) were constructed from experimentally measured fibril diameters and embedded in a nearly incompressible Mooney–Rivlin medium to transfer hydrostatic pressure to irregular fibril surfaces. Molecular dynamics (MD)-derived fibril properties at 300 K and 400 K were used to evaluate the effects of temperature, elastic–plastic deformation, and stochastic microstructure on void collapse and effective fiber properties. The 300 K elastic model required pressures approaching 1.3 GPa to reach approximately 1–2% void content, whereas the combined effects of elevated temperature, elastic–plastic fibril behavior, and stochastic fibril packing reduced the corresponding pressure to approximately 160 MPa. The stochastic RVE exhibited a higher initial void content, earlier plastic dissipation, lower initial effective stiffness, and nonuniform fibril–fibril contact evolution compared to the idealized hexagonal RVE. As void content decreased, both models converged toward the dense fibril response. The framework establishes a processing–microstructure–property relationship linking consolidation pressure to the evolving void morphology, fibril shape and contact development, and the resulting effective plane-strain bulk modulus and the transverse compressive stress–strain response, including the Young’s modulus and Poisson’s ratio, of UHMWPE fibers. Full article

In the preliminary vehicle design process, Finite Element Analysis (FEA) and Multi-Body Dynamics (MBD) simulations require detailed physical parameters that are not available during the conceptual design phase. This study proposes a novel analytical algorithm that uses a virtual weighting approach to rapidly establish a reasonable baseline for these parameters, serving as an efficient analytical precursor to the physical tests, complex dynamic simulations, and optimization methods conventionally applied in later stages. In this study, a dual-layer model for rapid geometric assessment of stability indices and vertical loads in hyperstatic 8 × 8 vehicles is proposed. The model consists of a prognostic Weighted Singular Value Decomposition (SVD) layer and an operative Weighted Pseudo-Inverse (WPI) layer. In the SVD layer, a spectral mode alignment technique is proposed to evaluate the load transmission capacity to predict the stability limits under worst-case operating conditions including extreme maneuvers and wheel failures. In the WPI layer, the optimal distribution of wheel loads is computed under different operating conditions. For a uniform vehicle configuration, a high-resolution continuous sweep of lateral acceleration identifies the exact wheel lift-off point at 0.8621 g, perfectly aligning with the theoretical Static Stability Factor (SSF). By employing a virtual weighting strategy instead of relying on traditional exhaustive physical parameters, this parameter-independent framework provides an analytical load-boundary evaluation and determines the theoretical topological capacity, thereby acting as an essential tool for preliminary conceptual design prior to detailed MBD and FEA analyses. Full article

Given the modernization of power systems in recent years, the quality of electrical energy is changing. With the increasing prevalence of harmonic components and rising current densities, conductor efficiency has become critically important. This study investigates the skin effect as a function of conductor geometry within the framework of electromagnetic field theory. Classical circular cross-section cable geometries and rectangular busbar systems were compared under an AC current of 1350 A (peak) across a frequency range of 50–500 Hz. The findings are comparatively presented, and their electromagnetic and thermal implications are discussed. Numerical modeling and simulation studies were performed using the Finite Element Method. COMSOL Multiphysics^® software AC/DC Module 6.2 version was used for the analyses. In the simulation studies, the magnetic flux density distribution within the conductor and the current concentration induced by eddy currents were analyzed. Frequency-dependent behavioral characteristics were examined in the analyses. The results revealed that the conductor with circular geometry exhibited a more severe skin effect. The rectangular conductor used in busbar systems was found to effectively distribute the current density across its surface area. Thus, rectangular geometry optimizes AC resistance. The analysis results revealed that conductor design and material selection depend not only on the cross-sectional area but also on the geometric shape factor. In this context, it was determined that conductor design has a decisive effect on electromagnetic power losses, which directly govern the heat generation potential within high-current systems. This study serves as a technical guide to evaluate frequency-dependent electromagnetic performance across a 50–500 Hz range—reflecting frequencies relevant to harmonic components—to assist in the design and optimization of high-current energy distribution systems. Full article

Vulnerable coastal urban margins face overlapping pressures from erosion, climate change, and plastic-waste accumulation. This study presents a screening-level numerical assessment of a hollow modular unit made of a recycled polyethylene terephthalate (PET)–concrete composite, proposed for coastal slope protection and stabilisation in Chucuito, Callao, Peru. A limit-equilibrium baseline indicates that the unprotected slope is marginal to unstable under the site’s seismic demand, motivating the evaluation of a surface-protection concept through a parallel, one-way finite element analysis–computational fluid dynamics (FEA–CFD) framework applied at three slope angles (60°, 53°, 45°). The FEA structural-response screening indicates consistent trends across configurations under an equivalent impact load and the adopted basal restraint. For the hydraulic comparison, inlet velocities of 3, 5 and 7 m/s were anchored to the site-specific Delft3D inundation modelling (site maximum 5 m/s), with a conservative 10 m/s upper bound; relative to a rip-rap reference, the hollow configuration suggests midpoint run-up velocity reductions of approximately 52% at θ = 53° under the conservative scenario and ≈57% at 3 and 5 m/s, falling to ≈25% at 7 m/s with overlapping ranges and the simulated free surface exceeding the crest. The CFD free-surface elevations show order-of-magnitude consistency with an indicative EurOtop-based run-up benchmark used as a consistency check rather than as hydraulic validation. Independent of this hydraulic comparison, the hollow geometry saves ≈ 62% of the material volume relative to an equivalent solid concrete block, valorises ≈ 793 post-consumer PET bottles per unit at a 10% dosage, and suggests a 42–58% embodied-CO₂ reduction relative to the same solid-concrete reference, driven mainly by the hollow geometry rather than by the PET substitution itself. The results are internally consistent but not experimentally validated and are intended as a comparative baseline to guide subsequent experimental and field studies, in line with Sustainable Development Goals (SDG) 11, 12 and 13. Full article

This study investigates the acoustic response of ZnO-based SAW devices fabricated on ZnO/Si and ZnO/SiO₂/Si substrates through a combined finite element analysis and experimental approach. Two-dimensional FEA was used to analyze scattering parameters, three-dimensional FEA was used to determine eigenfrequencies and mode shapes, and ZnO thin films were deposited by RF magnetron sputtering with interdigital transducers defined by UV lithography. The ZnO/SiO₂/Si device exhibited Rayleigh and Sezawa-type mode resonances at 145 MHz (4350 m/s) and 234 MHz (7020 m/s), respectively, in close agreement with simulation, while the ZnO/Si device resonated at 166 MHz with a phase velocity of 4980 m/s. Incorporation of the Au sensing layer improved signal transmission by approximately 2 dB, consistent with modeling predictions. For biosensing evaluation, the device was functionalized with a thiolated ssDNA probe targeting the EGFR L858R point mutation, a clinically relevant lung cancer biomarker. Probe immobilization and target hybridization were confirmed by contact angle measurements and resonance frequency shifts, with the sensor demonstrating a linear detection range of 0.1 to 0.6 µM and LOD of 0.09 µM. These findings establish an integrated framework of acoustic modeling, microfabrication, and biofunctionalization for ZnO-based SAW biosensors toward label-free nucleic acid detection. Full article