Search Results (1,587)

This research is based on the acoustic package design of new energy vehicles, investigating the application of the hybrid Finite Element–Statistical Energy Analysis (FE-SEA) model in predicting the high-frequency dynamic response of automotive structures, with a focus on the modeling and correction methods for hybrid point connections. New energy vehicles face unique acoustic challenges due to the special nature of their power systems and operating conditions, such as high-frequency noise from electric motors and electronic devices, wind noise, and road noise at low speeds, which directly affect the vehicle’s ride comfort. Therefore, optimizing the acoustic package design of new energy vehicles to reduce in-cabin noise and improve acoustic quality is an important issue in automotive engineering. In this context, this study proposes an improved point connection correction factor by optimizing the division range of the decision circle. The factor corrects the dynamic stiffness of point connections based on wave characteristics, aiming to improve the analysis accuracy of the hybrid FE-SEA model and enhance its ability to model boundary effects. Simulation results show that the proposed method can effectively improve the model’s analysis accuracy, reduce the degrees of freedom in analysis, and increase efficiency, providing important theoretical support and reference for the acoustic package design and NVH performance optimization of new energy vehicles. Full article

Objective: The material properties of craniofacial sutures significantly influence the outcomes of orthodontic treatment, particularly with newer appliances. This study specifically investigates how the Young’s modulus of craniofacial sutures impacts the anterosuperior protraction achieved using a recently developed extraoral appliance. Our goal is to identify the patterns by which suture properties affect skull deformation induced by this device. Materials and Methods: We conducted four finite element (FE) simulations to evaluate the Right Angle Maxillary Protraction Appliance (RAMPA) when integrated with an intraoral device (gHu-1). We tested Young’s moduli of 30 MPa, 50 MPa, and 80 MPa for the sutures, drawing on values reported in previous research. To isolate RAMPA’s effects on craniofacial deformation, we also performed an additional simulation with rigid sutures and a separate model that included only the intraoral device. Results: Simulations with flexible sutures showed consistent displacement and stress patterns. In contrast, the rigid suture model exhibited substantial deviations, ranging from 32% to 76%, especially in the maxillary palatine suture and orbital cavity. Both displacements and von Mises stresses were proportional to the Young’s modulus, with linear variations of approximately 15%. Conclusions: Our findings demonstrate that RAMPA effectively achieves anterosuperior protraction across a broad spectrum of suture material properties. This positions RAMPA as a promising treatment option for patients with long-face syndrome. Furthermore, the observed linear relationship (with a fixed slope) between craniofacial deformation and the Young’s modulus of sutures provides a crucial foundation for predicting treatment outcomes in various patients. Full article

Finite element (FE) models are widely used in structural health monitoring to represent real structures and assess their condition, but discrepancies often arise between numerical and actual structural behavior due to simplifying assumptions, uncertain parameters, and environmental influences. Temperature variation, in particular, significantly affects structural stiffness and modal properties, yet it is often treated as noise in traditional model updating methods. This study treats temperature changes as valuable information for model updating and structural damage quantification. The Bayesian model updating approach (BMUA) is a probabilistic approach that updates uncertain model parameters by combining prior knowledge with measured data to estimate their posterior probability distributions. However, traditional BMUA methods assume mass is known and only update stiffness. A novel BMUA framework is proposed that incorporates thermal buckling and temperature-dependent stiffness estimation and introduces an algorithm to eliminate the coupling effect between mass and stiffness by using temperature-induced stiffness changes. This enables the simultaneous updating of both parameters. The framework is validated through numerical simulations on a three-story aluminum shear frame under uniform and non-uniform temperature distributions. Under healthy and uniform temperature conditions, stiffness parameters were estimated with high accuracy, with errors below 0.5% and within uncertainty bounds, while mass parameters exhibited errors up to 13.8% that exceeded their extremely low standard deviations, indicating potential model bias. Under non-uniform temperature distributions, accuracy declined, particularly for localized damage cases, with significant deviations in both parameters. Full article

Precast prestressed hollow-core slabs (HCSs), primarily designed for uniformly distributed loads, frequently encounter concentrated loads, causing complex stress states. Load distribution occurs through longitudinal joints; however, the hollow cross-section and absence of transverse reinforcement increase susceptibility to shear, including punching. Existing guidelines offer limited guidance, often conflicting with experimental results. While limited previous studies have examined concentrated load effects on various HCS types, research on the Spancrete system—distinguished by unique core geometries—is lacking. This study presents a detailed numerical investigation of modified punching shear behavior in Spancrete HCS floors using a 3D finite element (FE) model developed in ABAQUS. The model, comprising three interconnected HCS units, was validated against experimental data from single-unit and full-scale floor tests exhibiting modified punching shear failure. Results show that modified punching shear in HCSs is driven initially by localized stress distribution in the top flange along one direction and secondarily by compression stresses in the loaded region, unlike the symmetric failure in solid slabs. While variations in loading area affected post-peak response, shifting the load closer to the longitudinal joints led to earlier joint debonding, reducing ultimate capacity. These insights challenge the adequacy of current design guidance and emphasize the necessity of refined HCS provisions. Full article

Prestressed concrete structures are facing serviceability challenges due to rising live loads, material degradation, and seismic demands. Retrofitting with carbon fiber-reinforced polymer (CFRP) offers a cost-effective alternative to full replacement. This study presents a finite element (FE) modeling framework to simulate the seismic performance of prestressed concrete T-beams retrofitted in the negative moment region using near-surface-mounted (NSM) CFRP rods and sheets. The model incorporates nonlinear material behavior and cohesive interaction at the CFRP–concrete interface and is validated against experimental benchmarks, with ultimate load prediction errors of 4.41% for RC T-beams, 0.49% for prestressed I-beams, and 1.30% for prestressed slabs. A parametric investigation was conducted to examine the influence of CFRP embedment depth and initial prestressing level under three seismic conditions. The results showed that fully embedded CFRP rods consistently improved the beams’ ultimate load capacity, with gains of up to 10.84%, 16.84%, and 14.91% under cyclic loading, near-fault ground motion, and far-field ground motion, respectively. Half-embedded CFRP rods also prove effective and offer comparable improvements where full-depth installation is impractical. The cyclic load–displacement histories, the time–load histories under near-fault and far-field excitations, stiffness degradation, and damage contour analysis further confirm that the synergy between full-depth CFRP retrofitting and optimized prestressing enhances structural resilience and energy dissipation under seismic excitation. Full article

Parametric optimization/inversion of Interferometric Synthetic Aperture Radar (InSAR) measurements enables the modeling of the volcanic deformation source by considering the approximation of the analytic formulations or by defining refined scenarios within a Finite Element (FE) framework. However, the geodetic data modeling can lead to ambiguous solutions when constraints are unavailable, turning out to be time-consuming. In this work, we use an integrated multiscale approach for retrieving the geometric parameters of volcanic deformation sources and then constraining a Monte Carlo optimization of FE parametric modeling. This approach allows for contemplating more physically complex scenarios and more robust statistical solutions, and significantly decreasing computing time. We propose the Campi Flegrei caldera (CFc) case study, considering the 2019–2022 uplift phenomenon observed using Sentinel-1 satellite images. The workflow firstly consists of applying the Multiridge and ScalFun methods, and Total Horizontal Derivative (THD) technique to determine the position and horizontal sizes of the deformation source. We then perform two independent cycles of parametric FE optimization by keeping (I) all the parameters unconstrained and (II) constraining the source geometric parameters. The results show that the innovative application of the integrated multiscale approach improves the performance of the FE parametric optimization in proposing a reliable interpretation of volcanic deformations, revealing that (II) yields statistically more reliable solutions than (I) in an extraordinary tenfold reduction in computing time. Finally, the retrieved solution at CFc is an oblate-like source at approximately 3 km b.s.l. embedded in a heterogeneous crust. Full article

This study investigated the tensile behaviors of 12.70 mm and 15.20 mm diameter anchor cable specimens with ultimate tensile strengths of 1860 MPa and their material specimens through experiments and finite element (FE) simulations. Material specimens and anchor cable specimen tensile samples were prepared, and the complete engineering stress–strain curves were obtained via uniaxial tensile tests. FE analysis was used to simulate the uniaxial tensile tests, and the applicability of different constitutive models for describing the true stress–strain relationships was evaluated by comparing the simulated and experimental engineering stress–strain curves. The results showed that the Ludwik, Hollomon, and Swift models, fitted using the pre-necking hardening stage, overestimated the post-necking true stress, while the Voce model underestimated it. In contrast, the Ling and Swift + Voce models provided accurate post-necking true stress predictions. Based on the Ling model and the Rice and Tracey fracture criterion, the load–displacement relationship and fracture behavior of the 12.7 mm anchor cable specimen were best described with W = −0.1 and a = 2, whereas W = −0.1 and a = 3 yielded optimal predictions for the 15.2 mm anchor cable specimen. Full article

While laser-assisted turning (LAT) improves the machinability of GH 4169 through heating-induced thermal softening, revealing the influence of the laser processing parameters on its thermal field and machining efficiency is crucial. In this study, the influence of different laser processing parameters on the thermal field during the preheating process of LAT is systematically investigated by combining finite element (FE) simulation and experimentation, from which the optimal processing parameters of the LAT of GH 4169 are obtained. Firstly, the experimental platform of LAT is established, and a 2D FE model of the LAT of GH 4169 is constructed. Secondly, the absorption coefficient of GH 4169 with a 1064 nm wavelength laser is calibrated through experimentation and FE simulation, which lay an accurate foundation for the subsequent thermal field analysis. Furthermore, the FE simulation of the preheating process of the LAT of GH 4169 is carried out, focusing on the influence of laser power, laser spot diameter, laser spot movement speed and laser spot–tool edge distance on the thermal field, in terms of the peak and final preheating temperatures. The results show that laser power, laser spot movement speed and laser spot diameter have a significant influence on both of the two temperatures, while laser spot–tool edge distance only affects the final preheating temperature. In addition, the regression equations of the peak and final preheating temperatures are obtained based on the FE simulation results, and the optimal processing parameters are determined by combining the boundary conditions (peak temperature of 650–950 °C and initial preheating temperature of ≤190 °C). Comparison experiments with conventional turning (CT) show that under the optimal processing parameters, LAT can effectively reduce the cutting force, surface roughness and tool flank wear, which indicates that a rational selection of laser processing parameters is crucial for improving the capability of LAT of GH 4169. Full article

For the flexible multi-point stretch-bending forming process, which involves complex forming procedures, finite element (FE) modeling can significantly reduce trial-and-error costs and provide a convenient means for determining process parameters in actual production. During the creation of FE models, simplifying the material model is crucial: insufficient simplification greatly increases computation time, while excessive simplification reduces model accuracy. This study establishes user material subroutines in the FE simulation software Abaqus to introduce anisotropic yield models, specifically Hill’s 48 and Yld2004-18p models. Multi-point stretch-bending experiments were repeated and compared with simulations using the traditional isotropic Von Mises yield model to analyze the impact of isotropic simplification on the accuracy of forming results. The applicability of isotropic simplification under different degrees of deformation is investigated, and the fundamental causes of errors are analyzed. Ultimately, the error response of the material simplified model is obtained. This provides an error reduction scheme for subsequent research using the isotropic simplified model. Full article

Reinforced concrete (RC) non-seismic frames in Middle Eastern multistory buildings often have beam–column connections with discontinuous bottom reinforcement, heightening the risk of progressive collapse if an outer column fails. This study aimed to reduce the potential for progressive collapse when a column is lost by investigating the use of bolted steel plates to enhance the beam–column joints of such frames. In this regard, high-fidelity finite element (FE) analysis was carried out on ten half-scale, two-span, two-story RC frames to simulate the removal of a center column. The numerical analysis accounted for the nonlinear rate-dependent response of steel and concrete, as well as the bond-slip model at steel bars/concrete interaction. The analysis matrix had three unstrengthened specimens that served as references for comparison, in addition to seven assemblies, which were strengthened using bolted steel plates. In the upgraded assemblies, the studied variables were the grade of steel plate (three grades were examined) and the upgrading scheme (three different schemes were investigated). The performance of the specimens was evaluated by comparing their failure patterns and the characteristics of load versus displacement of the middle column during both flexural and catenary action phases. Based on this comparison, the most efficient strengthening method was suggested. Full article

This study employed tensile test, hydrogen permeation measurements, and potentiodynamic polarization testing to investigate the mechanical properties, hydrogen diffusion coefficients, and electrochemical behavior of X80 steel. A multifield coupled finite element (FE) model was developed that incorporated the mechano-electrochemical (M-E) effect to analyze the stress–strain distribution, anodic equilibrium potential, cathodic exchange current density, and hydrogen distribution characteristics at pipeline corrosion defects under varying tensile strains. The results indicated that tensile strain significantly modulated the anodic equilibrium potential and cathodic exchange current density, leading to localized hydrogen accumulation at corrosion defects. The stress concentration and plastic deformation at the defect site intensified as the tensile strain increased, further promoting hydrogen enrichment. The study concluded that the M-E effect exacerbated hydrogen enrichment at the defect sites, increasing the risk of hydrogen-induced cracking. The simulation results showed that the hydrogen distribution state aligned with the stress–hydrogen diffusion coupling model when considering the M-E effect. However, the M-E effect slightly increased the hydrogen concentration at the defect. These findings provide critical insights for enhancing the safety and durability of hydrogen transmission pipelines. Full article

Silicon-based MEMS devices are essential in extreme radiation environments but suffer progressive reliability degradation from irradiation-induced defects. Here, the generation, aggregation, and clustering of defects in single-crystal silicon were systematically investigated through molecular dynamics (MD) simulations via employing a hybrid Tersoff–ZBL potential that was validated by nanoindentation and transmission electron microscopy. The influences of the primary knock-on atom energy, temperature, and pre-strain state on defect evolution were quantified in detail. Frenkel defects were found to cause a linear reduction in the Young’s modulus and a nonlinear decline in thermal conductivity via enhanced phonon scattering. To link atomic-scale damage with device-level performance, MD-predicted modulus degradation was incorporated into finite element (FE) models of a sensing diaphragm. The FE analysis revealed that modulus reductions result in nonlinear increases in deflection and stress concentration, potentially impairing sensing accuracy. This integrated MD–FE framework establishes a robust, physics-based approach for predicting and mitigating irradiation damage in silicon-based MEMS operating in extreme environments. Full article

This study aims to investigate the bond behavior at earthen mortar–brick interfaces in historic masonry structures. To that end, a series of combined compression–shear tests were conducted to systematically assess the influence of varying water–soil ratios and applied lateral compression on interfacial bond behavior. A fully decoupled microscopic finite element (FE) framework employing cohesive elements was developed to simulate the bond strength of earthen mortar–brick interfaces and validated using Spearman correlation analysis. The results indicate that increasing lateral compression markedly enhances both the peak displacement and shear strength, although it also reduces inter-specimen correlation by 18%. Notably, even under high lateral compression, the finite element predictions maintained a strong correlation with experimental data (R = 0.86), with a maximum deviation of less than 5%, demonstrating the model’s capability to accurately simulate the bond behavior of loess earthen mortar in masonry. These findings provide essential data and a robust computational framework for the preventive conservation of historic masonry structures. Full article

The development of underground space, as a critical strategy for enhancing urban land use efficiency, requires careful consideration of the effects that new construction may have on existing foundations and structures to prevent safety hazards such as foundation damage. This paper investigates the influence of shield tunnel construction on the pile foundations of adjacent bridges. Based on the shield tunnel project intersecting the Haiqin Bridge pile foundations along a segment of the Guangzhou–Zhuhai Intercity Railway as a case study, a finite element (FE) model was developed. The validity of the numerical method was confirmed through comparison with existing model test results. Building on this foundation, this paper analyzed the impact patterns of shield tunnel construction on existing bridge pile foundations. Additionally, the model was employed to assess how variables such as the relative spatial positioning between the pile foundations and the tunnel, as well as the stiffness coefficient of the pile foundations, affect the structural response of the piles. The findings reveal that shield tunnel construction crossing adjacent bridge pile foundations induces bending deformation of the piles toward the tunnel side. The maximum horizontal displacement and internal forces occur near the tunnel axis, whereas the peak vertical displacement is observed at the pile head. The zone most affected by tunnel excavation extends approximately one tunnel diameter (1D) before and after the pile foundation location. The vertical relative position between the tunnel and pile foundation governs the relative displacement behavior between the pile and surrounding soil during excavation. Specifically, when the pile toe moves downward relative to the tunnel, the excavation’s influence on the pile foundation shifts from being dominated by negative skin friction and settlement to positive skin friction and rebound, leading to substantial changes in the force distribution and displacement patterns within the pile. As the horizontal clearance between the tunnel and pile foundation increases, the internal forces and displacements within the pile foundation progressively diminish and eventually stabilize. Furthermore, an increase in pile stiffness coefficient decreases the maximum pile displacement and increases internal forces in the pile shaft. Pile diameter has a greater influence than Young’s modulus, which exhibits a relatively minor effect. Full article

CoCrFeNiMn high entropy alloy (HEA) fabricated via laser-based powder bed fusion (PBF-LB/M) exhibits exceptional mechanical properties, including high strength, better ductility than titanium alloy, and superior corrosion resistance. This study simulates the intergranular fracture behavior of PBF-LB/M CoCrFeNiMn HEA under tensile loading by embedding cohesive elements with damage mechanisms into polycrystalline representative volume elements based on the crystal plasticity finite element method. The simulation results show good agreement with reported experimental stress–strain curves, demonstrating that the crystal plastic constitutive model combined with the cohesive constitutive model can accurately describe both the macroscopic response behavior and fracture failure behavior of the CoCrFeNiMn HEA. Furthermore, this work investigates the mechanical properties of the HEA in different tensile directions, the improvement of anisotropy through columnar-to-equiaxed grain transition, and the effect of texture strength on crack initiation and propagation. The results show that the polycrystalline CoCrFeNiMn HEA exhibits anisotropic mechanical properties: simulated yield strengths (YSs) are 436.9 MPa (in the scanning direction) and 484.7 MPa (in the building direction), tensile strengths (TSs) reach 639 MPa and 702.5 MPa, and elongations (ELs) are 10.6% and 21.8%, respectively. After equiaxed grain formation, the EL in the scanning direction increased from 10.6% to 17.2%, while the EL in the building direction decreased from 21.8% to 20.3%. Concurrently, the anisotropy coefficients of YS, TS, and EL decreased by 1.8%, 2.2%, and 36.1%, respectively. The cracks initiate at stress concentrations and subsequently propagate along grain boundaries until final fracture. Variations in texture strength significantly influence the crack initiation location and propagation path in the CoCrFeNiMn HEA. Full article