Search Results (2,362)

This study presents a newly developed program that seamlessly converts G-code into formats compatible with Abaqus, enabling precise finite element simulations for FDM 3D printing. The tool operates on a two-pronged framework: a mathematical model incorporating key print parameters (layer thickness, extrusion temperature, print speed, and raster width) and a shape generator managing geometric parameters (fill density, pattern, and raster orientation). Initially, a predefined virtual section, based on predetermined dimensions, enhanced the correlation between experimental results and simulations. Subsequently, a corrected virtual section, derived from the mathematical model using the Box–Behnken methodology, improves accuracy, achieving a virtual thickness error of 1.06% and a width error of 8%. The model is validated through tensile testing of ASTM D638 specimens at 0°, 45°, and 90° orientations, using adaptive C3D4 mesh elements (0.35–0.6 mm). Results demonstrate that the corrected cross-section significantly improved simulation accuracy, reaching correlations above 95% in the elastic zone and 90% in the elastoplastic zone across all orientations. By optimizing the workflow from design to manufacturing, this program offers substantial benefits for the aerospace, medical, and automotive sectors, enhancing both the efficiency of the printing process and the reliability of simulations. Full article

Accurately determining the modulus of each structural layer remains a key challenge in asphalt pavement design, construction quality control, and bearing capacity assessment. This study introduces an ensemble model combining a genetic algorithm-optimized backpropagation neural network (GA-BP) and a convolutional neural network (CNN) to back-calculate the dynamic modulus of asphalt pavement layers over rubblized old cement concrete structures. Using a dynamic deflection basin database created by our research team, we built a dataset of 1,552,000 pavement structure samples with Falling Weight Deflectometer (FWD) data. Based on this dataset, we developed regression models, including a backpropagation (BP) neural network, GA-BP, and CNN, to perform the back-calculation of dynamic modulus values. Performance testing revealed that the CNN model outperformed both the GA-BP and BP models in terms of accuracy and stability, as indicated by evaluation metrics (R², MAE, RMSE, MAPE), with the following ranking: CNN > GA-BP > BP. Nonetheless, the maximum relative error across all three models remained notable. To address this, an ensemble model combining GA-BP and CNN was created, significantly enhancing the accuracy and stability of the back-calculation results. The proposed ensemble model was tested on-site with FWD data to estimate the dynamic modulus of asphalt pavement layers. The results demonstrated strong agreement with actual pavement performance and high consistency with numerical outcomes from three-dimensional (3D) dynamic finite element method simulations. These findings suggest that the GA-BP and CNN ensemble approach offers a reliable method for back-calculating the dynamic modulus of asphalt pavement layers over rubblized old cement concrete structures. Full article

This study focuses on the behavior of hybrid polymer composites made from glass fiber and natural fiber-based flax fabric when subjected to low velocity drop-weight impacts. With the rise in the utilization of composites in structural components in various industries like the marine, aerospace and automotive industries, it is of paramount importance to study the effects of low velocity drop-weight impacts and their damage assessment on the composites. Low velocity drop-weight impacts can occur due to a tool falling on a composite part or due to an impact with a small object. The experimental tests were carried out according to ASTM standards with a drop-weight impact testing machine. Simulations were done to replicate the tests using explicit finite element software LS-DYNA. The experimental tests were carried out on samples of thickness ~2.5 mm and the energy at impact was 50 J. Upon comparing the experimental results, it was seen that an error percentage in the deformation varied between a minimum of 3.32% and a maximum of 8.93%, and the maximum force at impact varied between a minimum of 0.06% and a maximum of 17.14%. The variations between the experimental and simulated values can be attributed to the presence of voids or other defects that would have inadvertently crept in while making the composite. Additionally, composite laminates lined with a layer of EPS (expanded polystyrene) foam were tested and compared with composite laminates which were not lined with the foam. An improvement in the performance of the composite laminates lined with the EPS foam was observed. Full article

To clarify the influence of reinforcement corrosion on the mechanical performance of road tunnel linings, localized tests on reinforcement-induced concrete expansion are conducted to identify cracking patterns and their effects on load-bearing behavior. Refined three-dimensional finite element models of localized concrete and the entire tunnel are developed using the concrete damaged plasticity model and the extended finite element method and validated against experimental results. The mechanical response and crack evolution of the lining under corrosion are analyzed. Results show that in single-reinforcement specimens, cracks propagate perpendicular to the reinforcement axis, whereas in multiple-reinforcement specimens, interacting cracks coalesce to form a π-shaped pattern. The cover-layer crack width exhibits a linear relationship with the corrosion rate. Corrosion leads to a reduction in the stiffness and load-bearing capacity of the local concrete. At the tunnel scale, however, its influence remains highly localized, and the additional deflection exhibits little correlation with the initial deflection. Local corrosion causes a decrease in bending moment and an increase in axial force in adjacent linings; when the corrosion rate exceeds about 15%, stiffness damage and internal force distribution tend to stabilize. Damage and cracks initiate around corroded reinforcement holes, extend toward the cover layer, and connect longitudinally, forming potential spalling zones. Full article

In this study, the free vibration characteristics of a functionally graded (FG) shear-deformable Timoshenko beam were investigated both analytically and numerically. The work is notable for its significant contribution to the literature, particularly in addressing analytically challenging problems related to complex FGM structures using advanced computer-aided finite element methods. For the analytical approach, the governing equations and associated boundary conditions were derived using Hamilton’s principle of minimum potential energy. These equations were then solved using the Navier solution method to determine the natural frequencies of the beam. In the numerical analysis, a 3D FG beam model was developed in the ABAQUS finite element software (2023, Dassault Systèmes, Providence, RI, USA)using the second-order hexahedral (HEX20/C3D20) and 1D three-node quadratic beam (B32) elements. The material gradation was defined layer-by-layer along the thickness direction in accordance with the rule of mixtures. Modal analysis was subsequently performed to extract the natural frequency values. The results show a high level of agreement between the analytical and numerical solutions. and were consistent with previously published studies in the literature. Full article

With the rapid development of communication, electronics, medical, and energy industries in modern society, film capacitors have garnered widespread attention and undergone significant growth. However, the low energy density (U_e) resulting from low breakdown strength (E_b) significantly limits the application of thin-film capacitors. In this work, we use a low-cost and effective dip-coating method to apply boron nitride (BN) layers onto the outer layers of poly(vinylidene fluoride-co-hexafluoropropylene)/barium titanate (P(VDF-HFP)/BT) composite films to prepare boron nitride-poly(vinylidene fluoride-co-hexafluoropropylene/barium titanate-boron nitride (BN-P(VDF-HFP)/BT-BN) composite films with a sandwich structure that exhibits extremely high E_b and U_e. The experimental results show that the sandwich-structured BN-P(VDF-HFP)/BT-BN films containing 7.5 wt% BT nanoparticles obtained 530 MV/m E_b and 18.12 J/cm³ U_e, both of which are much higher than those of the corresponding monolayer films. In addition, the finite element simulation results show that the designed sandwich-structured films can reduce local field strength distortion, decrease leakage current, and suppress the development of breakdown channels, thereby significantly improving E_b and U_e. In summary, this study presents a low-cost and effective method for enhancing the breakdown strength and energy density of thin-film capacitors. Full article

Predicting the Remaining Useful Life (RUL) of light aircraft landing gear is complicated by flight-to-flight variability in operational loads, particularly in sensor-free fleets that rely only on mass-and-balance records. This study develops a hybrid physics–data framework to quantify operational-load-driven uncertainty in the main landing gear strut of a Cessna 172. High-fidelity finite-element strain–life simulations were combined with a quadratic Ridge surrogate and a two-layer bootstrap to generate full probabilistic RUL distributions. The surrogate mapped five mass-and-balance inputs (fuel, front seats, rear seats, forward and aft baggage) to per-flight fatigue damage with high accuracy (R² = 0.991 ± 0.013). At the same time, ±3% epistemic confidence bands were attached via resampling. Borgonovo’s moment-independent Δ indices were applied to incremental damage (ΔD) in this context, revealing front-seat mass as the dominant driver of fatigue variability (Δ = 0.502), followed by fuel (0.212), rear seats (0.199), forward baggage (0.141), and aft baggage (0.100). The resulting RUL distribution spanned 9 × 10⁴ to >2 × 10⁶ cycles, with a fleet average of 0.41 million cycles (95% CI: 0.300–0.530 million). These results demonstrate that operational levers—crew assignment, fuel loading, and baggage placement—can significantly extend strut life. Although demonstrated on a specific training fleet dataset, the methodological framework is, in principle, transferable to other aircraft or mission types. However, this would require developing a new, component-specific finite element model and retraining the surrogate using a representative set of mass and balance records from the target fleet. Full article

Background/Objectives: A mechanistic understanding of transdermal drug delivery relies on accurately capturing the layered structure and barrier function of the skin. This study presents a four-layer numerical model that explicitly includes the donor compartment, stratum corneum (SC), viable skin (RS), and receptor compartment. Methods: The model is based on Fickian diffusion and incorporates interfacial partitioning and mass transfer resistance. It is implemented using the finite element method in MATLAB and calibrated through nonlinear least-squares optimization against experimental data from Franz diffusion cell studies using porcine skin. Validation was performed using receptor concentration profiles over time and final drug content in the SC and RS layers, assessed via tape stripping and residual skin analysis. Results: The model provided excellent agreement with experimental data. For diclofenac, the optimized partition coefficient at the SC–RS interface was close to unity, indicating minimal interfacial discontinuity and that a simplified three-layer model may be sufficient for this compound. Conclusions: The proposed four-layer framework provides a physiologically informed and generalizable platform for simulating transdermal drug delivery. It enables spatial resolution, mechanistic interpretation, and flexible adaptation to other drugs and formulations, particularly those with significant interfacial effects or limited lipophilicity. Full article

Earthquakes are highly unpredictable and often lead to secondary disasters such as slope collapses, landslides, and debris flows, posing serious threats to human life and property. To explore how multi-stage loess slopes respond to seismic loading, improve both the efficiency and precision of seismic analysis, and better capture the random characteristics of earthquakes in reliability assessment, this research proposes a new analytical framework. The approach adopts the pseudo-dynamic method, divides the slope soil into layers through the lumped mass scheme, and applies the Newmark-β integration method to construct a displacement response model that incorporates seismic variability. By comparing and analyzing results from Geo-Studio finite element simulations, the study reveals the dynamic response behavior of multi-level loess slopes subjected to seismic loads. The key findings are as follows: (1) The formation of unloading platforms introduces a graded energy dissipation effect that significantly reduces stress concentration along potential sliding surfaces; (2) The combined influence of the additional vertical load from the overlying soil and the presence of double free faces has a notable effect on the stability of secondary slopes; (3) The peak displacement response exhibits a nonlinear relationship with slope height, initially increasing and then decreasing. The proposed improved analysis method demonstrates clear advantages over traditional approaches in terms of computational efficiency and accuracy, and provides a valuable theoretical basis for the seismic design of high loess slopes. Full article

This study investigates the double-sided hot cladding of an experimental Al–2%Cu–1.5%Mn–1%Zn–0.7%Mg–0.4%Fe–0.4%Si alloy with commercially pure aluminum A1050 under combined hot deformation. Finite element modeling was employed to analyze the evolution of shear strains, normal stresses, and flow stresses in the deformation zone during cladding. The results indicate that increasing the degree of reduction significantly alters the distribution and direction of shear strains: at low reductions (20–30%), shear directions in the base and cladding layers coincide, while reductions above 40% induce opposing shear directions. Temperature was identified as the dominant factor affecting normal stress and flow stress differences between layers, whereas deformation magnitude primarily influenced peak stresses at the neutral section of the deformation zone. Experimental validation was conducted over a temperature range of 300–450 °C and relative reductions of 20–60%, demonstrating successful layer bonding in all cases except at low temperatures and reductions (300–375 °C, 20–30%). Based on combined modeling and experimental data, a predictive model for estimating peel strength during hot rolling cladding was developed, offering a robust tool for optimizing process parameters and ensuring reliable interlayer bonding in investigated aluminum alloys. Full article

This study presents numerical simulations of ice crystal accretion on aircraft surfaces under mixed-phase icing conditions, where ice crystals coexist with supercooled water droplets. The Finite Element Navier–Stokes Analysis Program (FENSAP-ICE) suite, incorporating the Discrete Roughness Optimization Program in 3D (DROP3D) and Ice Accretion Simulation in 3D (ICE3D) solvers, was applied to the Common Research Model with Natural Laminar Flow (CRM-NLF) to examine the effects of crystal size, aspect ratio, and concentration on ice growth. The results show that the presence of ice crystals produces smoother, more uniform, and substantially thicker ice compared with droplet-only cases, where distinct horns and roughness dominate. At peak growth locations, the predicted ice thickness increases by up to 75% under mixed-phase conditions. Quantitative analyses reveal that increasing crystal diameter from 50 μm to 200 μm raises ice growth by 25%–75%, increasing aspect ratios from 0.05 to 1 increases growth by 20%–75%, and raising concentrations from 0.25 to 2 kg/m³ enhances growth by nearly 450%. These findings demonstrate the critical role of ice crystals in promoting layered ice accumulation, clarify the mechanisms driving mixed-phase icing, and provide theoretical guidance for advancing anti-icing and de-icing technologies in aviation. Full article

While methods like cyclic triaxial testing and p-y model updating theory exist in geotechnical and offshore wind engineering, they have not been systematically applied to solve the specific deformation problems of offshore PV piles. This study investigates a specific offshore photovoltaic (PV) project in Qinhuangdao City, Hebei Province. Initially, field tests of horizontal static load on steel pipe pile foundations were conducted. A finite element model (FEM) of single piles was subsequently developed and validated. Further analysis examined the failure modes, initial stiffness, and ultimate resistance of offshore PV single piles in sandy soil foundations under varying pile diameters and embedment depths. The hyperbolic p-y curve model was modified by incorporating pile diameter size effects and embedment depth considerations. Key findings reveal the following: (1) The predominant failure mechanism of fixed offshore PV monopiles manifests as wedge-shaped failure in shallow soil layers. (2) Conventional API specifications and standard hyperbolic models demonstrate significant deviations in predicting p-y (horizontal soil resistance-pile displacement) curves, whereas the modified hyperbolic model shows good agreement with field measurements and numerical simulations. This research provides critical data support and methodological references for calculating the horizontal bearing capacity of offshore PV steel pipe pile foundations. Full article

Wall plate rupture in liquid storage structures (LSSs) induced by earthquakes is a prevalent issue. To mitigate the impacts of seismic hazards on plate–shell composite concrete liquid storage structures (CLSSs), in this study, we propose an investigation into X-type mild steel–Shape Memory Alloy (SMA) seismic mitigation control for plate–shell composite CLSSs with sand-layer seismic isolation. Via finite element parametric analysis, this study examines the effects of two key parameters—the sand-layer friction coefficient and the spring-damping ratio of X-type mild steel–SMA seismic mitigation elements—on the dynamic response of CLSSs. The results indicate the following: under unidirectional seismic excitation, the proposed mitigation method achieves a favorable control effect on the maximum principal stress of the structure; under bidirectional seismic excitation, the optimal control effect on the maximum principal stress is achieved when the spring-damping ratio of the mitigation elements is 0.3 and the friction coefficient of the seismic isolation sand layer is 0.4. Additionally, under both unidirectional and bidirectional seismic excitation, this method exhibits a noticeable control effect on the peak liquid sloshing height. Full article

As an emerging type of non-volatile memory, magneto-resistive random access memory (MRAM) stands out for its exceptional reliability and rapid read–write speeds, thereby garnering considerable attention within the industry. The memory cell architecture of MRAM is centered around the magnetic tunnel junction (MTJ), which, however, is prone to interference from external magnetic fields—a limitation that restricts its application in demanding environments. To address this challenge, we propose an innovative open magnetic shielding structure. This design demonstrates remarkable shielding efficacy against both in-plane and perpendicular magnetic fields, effectively catering to the magnetic shielding demands of both spin-transfer torque (STT) and spin–orbit torque (SOT) MRAM. Finite element magnetic simulations reveal that when subjected to an in-plane magnetic field of 40 mT, the magnetic field intensity at the chip level is reduced to nearly 1‰ of its original value. Similarly, under a perpendicular magnetic field of 40 mT, the magnetic field at the chip is reduced to 2‰ of its initial strength. Such reductions significantly enhance the anti-magnetic capabilities of MRAM. Moreover, the magnetic shielding performance remains unaffected by the height of the packaging structure, ensuring compatibility with various chip stack packaging requirements across different layers. The research presented in this paper holds immense significance for the realization of highly reliable magnetic shielding packaging solutions for MRAM. Full article

A critical aspect in the design of power electronics packages is the prediction of their mechanical response under severe thermomechanical loads and the consequent structural damage. For this purpose, finite element (FE) simulations are used to estimate the mechanical performance and reliability under operational conditions, typically alternate high voltages/currents resulting in thermal gradients. When simulations are performed, it is common practice to consider the as-received package to be in a stress-free state. Namely, residual stresses and plastic deformation induced by the manufacturing processes are neglected. In this study, an advanced FE modeling approach is proposed to assess the structural consequences of the encapsulating resin curing, typical in the production of silicon carbide (SiC)-based power electronics modules for electric vehicles. This work offers a general modeling framework that can be further employed to simulate the effects of thermal gradients induced by the production process on the effective shape and residual stresses of the as-received package for other manufacturing stages, such as metal brazing, soldering processes joining copper and SiC, and, to lower extents, the application of polyimide on top of passivation layers. The obtained results have been indirectly validated with experimental data from literature. Full article