Search Results (618)

This study aimed to evaluate, through finite element analysis (FEA), the biomechanical behavior of edentulous maxillary overdentures supported on 2, 3, and 4 implants with conometric connections, and to determine the minimum implant number that maintains stresses within physiological limits. A 3D finite element model of a resorbed edentulous maxilla was generated from CT images and processed in ANSYS v19.0. Subsequently, six models were simulated according to implant number (2, 3, or 4) and cortical bone thickness (0.5 mm or 1 mm). Conical connection implants and cobalt–chromium-reinforced overdentures with Equator attachments were modeled. Bilateral axial loads were applied and Von Mises equivalent stresses were calculated for implants and abutments, while maximum and minimum principal stresses were analyzed in bone. Results showed that the highest deformation and stress concentrations were observed in the two-implant models, with trabecular stresses ranging from 6.5 to 8.4 MPa, exceeding the 5 MPa safety threshold. In contrast, both three- and four-implant models maintained trabecular stresses below 3 MPa, while keeping cortical bone stresses within physiological limits. The three-implant tripod configuration demonstrated a comparable stress distribution to the four-implant models. From a biomechanical perspective, overdentures supported on four implants with 1 mm cortical thickness showed the most favorable performance. Nevertheless, the three-implant model represented a biomechanically acceptable and potentially cost-effective alternative, suggesting its viability as a simplified clinical option that warrants further investigation. Full article

While incorporating constructional columns into masonry walls enhances structural integrity, their seismic bearing capacity remains relatively low. In contrast, composite structures formed through the integration of large-section concrete columns with masonry walls can significantly improve seismic performance. This study employed an integrated approach of model testing and numerical analysis to investigate the seismic behavior of composite structures consisting of large-section reinforced concrete columns and brick masonry walls. Specifically, three scaled model tests were carried out, and finite element analysis (FEA) was performed on six full-scale models, with the aim of elucidating the failure mechanism and mechanical properties of such composite structures. The results show that concrete columns effectively inhibit crack propagation in the walls, and the bearing capacity and ductility of the composite structures are significantly enhanced. Furthermore, a formula for the calculation of the horizontal bearing capacity of the composite structures was proposed based on the failure modes observed in the tests. The bearing capacity of four types of composite structures is calculated, and the differences between the calculated results and the FEA results do not exceed 10%, which provides a reference for the calculation of the lateral bearing capacity of composite structures. Full article

In this paper, the effect of eddy-current losses of permanent magnets (PMs) is studied by conducting analyses and experiments. PM segmentation is used to reduce eddy-current losses. Nowadays, many researchers are focusing on improving the efficiency and torque of permanent magnet synchronous motors (PMSMs), particularly in electric vehicle applications. This study evaluates PM eddy-current losses of an in-wheel-type PMSM designed for light electric vehicle (LEV) propulsion. Improving output torque and efficiency is essential in this type of direct-drive application. The eddy-current losses of PMs can be reduced by forming PMs as electrically isolated magnet segments. PM segmentation leads to shorter paths and reduces the values of eddy-currents, creating reduced magnetic losses. The improvement in torque production capability also implies an improvement in efficiency. To investigate the validity of PM segmentation, a three-dimensional (3D) finite element analysis (FEA) software is used for non-segmented (monolithic) and segmented cases. The experimental study is conducted using monolithic PM and segmented PM rotor assemblies. This study demonstrates the contribution of PM segmentation to torque production. Full article

In spoke-type permanent magnet synchronous motors (PMSMs), an asymmetric rib structure has been investigated as a method to reduce cogging torque. However, such rotor asymmetry tends to an increase in the axial force, which limits its applicability in precision and low-vibration systems. To overcome this limitation, this study proposes a new motor design method that introduces a skew factor as an additional design variable. The skew factor, defined as the ratio of the skewed region to the total stack length, enables simultaneous control of cogging torque and axial force by adjusting the degree of asymmetry along the rotor stack. Using parametric modeling and finite element analysis (FEA), the combined effects of the asymmetric rib and skew factor were investigated, and an optimized motor structure achieving balanced cogging torque and axial force characteristics was derived. The proposed design approach provides an effective method for simultaneously considering cogging torque and axial force in spoke-type PMSMs. Full article

Sinkholes caused by historical underground mining operations are significant geotechnical and safety hazards for new residential developments. This paper presents a case study concerning the assessment of the condition of the foundations of a planned multi-family residential building located within a former mining operations area in southern Poland, which is exposed to the risk of discontinuous ground deformation. This study aimed to identify potential voids within the rock mass and develop safe structural solutions for building foundations. To this end, a comprehensive site investigation was conducted, including two-dimensional electrical resistivity profiling to detect zones of high-resistivity anomalies. High-resistivity anomalies were identified beneath several building segments, suggesting the presence of voids or loose soil resulting from shallow coalmining operations. Based on these findings, a finite element analysis (FEA) of the reinforced concrete foundation slab was performed to simulate the presence of subsurface cavities. The results indicated local tensile stress in the slab of up to 0.34 MPa, which necessitated subsequent design adjustments. Consequently, the use of additional bottom reinforcement and continuous reinforced concrete ribs was proposed to enhance structural safety. This study highlights the necessity of detailed geotechnical and geophysical analyses of planned development zones located in former mining operation areas to address the risks related to sinkholes and ensure the long-term safety of new buildings. Full article

This study investigates the elastic properties of bio-epoxy composites reinforced with natural fibres (flax, hemp) and synthetic fibres (S-glass), with particular focus on the effect of the fibre volume fraction (VF) ranging from 10% to 70%. Three-dimensional representative volume element (RVE) models were developed for single-fibre, hybrid, and multi-fibre systems. The mean-field homogenisation (MF) approach, based on the Mori–Tanaka scheme, and finite element analysis (FEA) with periodic boundary conditions were employed to predict the effective elastic properties, including longitudinal, transverse, and shear moduli, as well as Poisson’s ratio. These numerical predictions were validated against analytical models, including the rule of mixtures, Chamis, and composite cylinder assemblage (CCA) methods. The results demonstrate that increasing the VF enhances longitudinal, transverse, and shear moduli while reducing Poisson’s ratio in natural fibre composites. The good agreement between numerical, semi-analytical, and analytical methods validates the 3D RVE models as useful tools for predicting the properties of multi-hybrid natural fibre composites, supporting their design for lightweight structural applications. Full article

Narrow-diameter implants (≤3.5 mm) have garnered significant attention due to their widespread application in areas with insufficient bone volume. However, their mechanical performance is limited. The cervical region, serving as a pivotal stress concentration zone, exhibits a thread form that directly modulates stress distribution and determines the long-term stability of the implant–bone interface. This study was designed to investigate the influence of varying thread forms and face angles on microstrain and stress distribution patterns in narrow-diameter implants (NDIs) and their adjacent cortical bone structures. Through systematic modification of implant thread forms and face angle parameters, finite element analysis (FEA) was employed to develop nine distinct implant models featuring varied geometric characteristics. Each model was implanted into Type III bone tissue, followed by the application of a 100 N occlusal force, including a vertical load and an oblique load deviated 30 degrees lingually from the long axis of the implants. Subsequent biomechanical evaluation quantified peak von Mises stress concentrations at the bone–implant interface, maximum equivalent elastic strain distributions in peri-implant bone tissue, and abutment stress profile characteristics. The results indicated that in the RB thread group, the optimal thread face angle parameter was 60 degrees; in the B thread group, this optimal thread face angle parameter was 45 degrees, whereas in the V thread group, the optimal thread face angle parameter was 30 degrees. Full article

This study reveals the Vierendeel mechanism of hybrid high-strength steel composite cellular beams (HHS-CCBs) through experimental investigation and finite element analysis (FEA). The forces acting on the openings of composite cellular beams (CCBs) are further analyzed. A calculation method is developed to evaluate the load-carrying capacity of HHS-CCBs under the combined action of bending moment and shear force, which takes into account the shear contributions of the concrete slab and beam flange at circular openings. The accuracy of the proposed formula and the influence of key parameters on load-carrying capacity are thoroughly examined through FEA. The results indicate that within the range of D = 0.6h_s − 0.7h_s and L = 0.7h_s − 1.0h_s (D and L represent the hole diameter and edge distance, respectively; h_s is the height of the steel beam), stress concentration at the beam-end welds could be avoided, the formation of Vierendeel mechanism at the beam-end opening could be ensured, and excessive reduction in load-carrying capacity could be prevented. Furthermore, the high-strength steel (HSS) flange strength and location had a minimal effect on the failure mode of HHS-CCBs. As the flange strength increased, full plasticity was not achieved in the cross-section, and the load-carrying capacity increased nonlinearly. Asymmetric specimens with HSS in the lower flange only and symmetric specimens with HSS in both the upper and lower flanges exhibited comparable load-carrying capacities. The load-carrying capacity calculation formula is applicable to HHS-CCBs with different section types, provided that circular holes are present in the beam web and Vierendeel mechanism damage occurs. However, the flange width–thickness ratio must not significantly exceed the specified limit. Full article

The central purpose of this study is to develop and validate an advanced numerical model capable of simulating the vibrational behavior of the operator’s seat in a tractor-type agricultural vehicle designed for operation in protected horticultural environments, such as vegetable greenhouses. The three-dimensional (3D) model of the seat was created using SolidWorks 2023, while its dynamic response was investigated through Finite Element Analysis (FEA) in Altair SimSolid, enabling a detailed evaluation of the natural vibration modes within the 0–80 Hz frequency range. Within this interval, eight significant natural frequencies were identified and correlated with the real structural behavior of the seat assembly. For experimental validation, direct time-domain measurements were performed at a constant speed of 5 km/h on an uneven, grass-covered dirt track within the research infrastructure of INMA Bucharest, using the TE-0 self-propelled electric tractor prototype. At the operator’s seat level, vibration data were collected considering the average anthropometric characteristics of a homogeneous group of subjects representative of typical tractor operators. The sample of participating operators, consisting exclusively of males aged between 27 and 50 years, was selected to ensure representative anthropometric characteristics and ergonomic consistency for typical agricultural tractor operators. Triaxial accelerometer sensors (NexGen Ergonomics, Pointe-Claire, Canada, and Biometrics Ltd., Gwent, UK) were strategically positioned on the seat cushion and backrest to record accelerations along the X, Y, and Z spatial axes. The recorded acceleration data were processed and converted into the frequency domain using Fast Fourier Transform (FFT), allowing the assessment of vibration transmissibility and resonance amplification between the floor and seat. The combined numerical–experimental approach provided high-fidelity validation of the seat’s dynamic model, confirming the structural modes most responsible for vibration transmission in the 4–8 Hz range—a critical sensitivity band for human comfort and health as established in previous studies on whole-body vibration exposure. Beyond validating the model, this integrated methodology offers a predictive framework for assessing different seat suspension configurations under controlled conditions, reducing experimental costs and enabling optimization of ergonomic design before physical prototyping. The correlation between FEA-based modal results and field measurements allows a deeper understanding of vibration propagation mechanisms within the operator–seat system, supporting efforts to mitigate whole-body vibration exposure and improve long-term operator safety in horticultural mechanization. Full article

This study presents a finite element analysis (FEA)-based numerical homogenization method for evaluating the effective thermo-mechanical properties of a large-area additively manufactured particulate-filled composite using realistic periodic representative volume elements (RVEs) generated from reconstructed X-ray µ-CT image scans of a 3D-printed bead. The numerical results of the predicted effective properties, including the elastic stiffness, coefficient of thermal expansion (CTE) and thermal conductivity, were benchmarked with the Mori–Tanaka–Benveniste analytical estimates, which were found to be comparable. Initial sensitivity analysis using a single region of interest (ROI) extracted from the bead’s volume was performed to determine a suitable RVE size. The impact of inherent micro-porosities on the resulting composite material’s behavior was also quantified in the current investigation and was shown to reduce the composite’s effective properties. Using a suitable RVE size, the effect of anisotropy due to spatial variation in the microstructure across the bead specimen on the computed composite’s effective properties was also assessed. The results show that the regions closer to the exposed surface of the print bead with highly aligned and densely packed fiber particulates have superior properties as compared to inner regions with a more randomly oriented and less densely packed fibrous microstructure. Full article

FEA of orthodontic miniscrews has predominantly assumed isotropic, homogeneous bone, neglecting directional variations in mechanical properties. This study investigated the biomechanical behavior of miniscrews under different insertion angles and loading directions using both isotropic and orthotropic mandibular bone models. The results indicated that isotropic modeling may underestimate miniscrew displacement and associated instability, whereas orthotropic material properties better reflect the true mechanical response of bone. Oblique insertion at 60° (U60°) led to higher strain and greater variability, which may compromise osseointegration; aligning the loading direction parallel to the insertion plane is therefore recommended when oblique placement is unavoidable. Screw thread design had minimal influence on displacement, von Mises stress, or bone strain during vertical insertion. Stress and strain distributions exhibited symmetry, suggesting that analyzing partial loading directions can predict the overall biomechanical response. All predicted values remained below bone and material strength limits, confirming the mechanical safety of the current miniscrew design under a 2 N load. Implant failure is likely attributable to poor osseointegration or inflammation rather than structural limitations. Full article

The mesh size significantly affects the accuracy and computational efficiency of finite-element analysis (FEA) simulations. This study investigates mesh regularization to mitigate mesh dependency, align numerical results with experimental data, and optimize the computational time for carbon/epoxy composites. Mesh regularization was implemented using the ^∗MAT_ADD_GENERALIZED_DAMAGE (MAGD) model in LS-DYNA, which incorporates a scaling factor based on the ply orientation and stress triaxiality to adjust the material failure criterion. To address the limitations of trial-and-error methods for determining scaling factors, four analytical models were developed to predict these factors as functions of element size. These predictions were validated against experimentally derived scaling factors for unidirectional carbon/epoxy composites across three ply orientations (0°, 45°, and 90°) and three stress triaxiality conditions (tension, compression, and shear) using mesh sizes ranging from 0.5 mm to 1.5 mm. The scaling factor effectively reduced the mesh dependency in the tested configurations. A clear relationship between ply orientation and mesh regularization was established; however, no definitive correlation was observed with stress triaxiality. Among the theoretical approaches, the stress degradation model yielded the most consistent predictions, although discrepancies with the experimental results indicate the need for further refinement. This study proposes integrating scaling factors into a material model as a practical approach to mesh regularization for orthotropic materials and evaluates existing theoretical models for predicting these factors. Full article

This study investigates the shear behavior of double-skin truss-reinforced composite shear walls through finite element analysis validated by published tests. Parametric studies reveal that the shear strength increases with the axial compression ratio up to a threshold of 0.6, beyond which it declines. However, increasing the aspect ratio significantly decreases the shear strength when the aspect ratio does not exceed 2.5. Additionally, increasing the spacing–thickness ratio reduces the shear strength, with a recommended limit of 60. Truss connector specifications are found to have a minor impact on the shear resistance. A new design formula for predicting the ultimate shear strength is established based on finite element analysis (FEA), which yields relatively conservative predictions with acceptable accuracy. Full article

High-speed solid rotor induction motors (HS-SRIMs) are favored for their robust structure but suffer from significant eddy current losses at high speeds, leading to efficiency reduction and thermal challenges. This study establishes a comprehensive multi-objective optimization framework to address this issue. The eddy current loss characteristics are first investigated using finite element analysis (FEA), focusing on the impact of key parameters like air gap length and rotor slotting. A sensitivity analysis quantifies their influence on motor performance. Subsequently, the Non-dominated Sorting Genetic Algorithm II (NSGA-II) is employed for multi-objective optimization, aiming to minimize eddy current loss while maximizing efficiency and electromagnetic torque. The optimization results demonstrate a significant improvement: a reduction in eddy current loss of 59.8%, an increase in efficiency of 17.2%, and a boost in output torque of 50.8%. Coupled electromagnetic–thermal simulations further validate a substantial decrease in operating temperatures. The proposed method provides an effective design approach for high-performance HS-SRIMs. Full article

Structural collapses are a major threat to urban safety and infrastructure resilience and as such there is growing research interest in understanding the causes and improving the prediction of risk to prevent human and material losses. Whether caused by fires, earthquakes or progressive failures due to overloads and displacements, these events have been the focus of investigation over the past 15 years. This systematic literature review looks at the use of formal risk analysis models in structural failures between 2010 and 2025 to map methodological trends, assess model effectiveness and identify future research pathways. From an initial database of 139 documented collapse incidents, only 42 were investigated using structured risk analysis frameworks. A systematic screening of 417 related publications yielded 101 peer-reviewed studies that met our inclusion criteria—specifically, the application of a formal analytical model. This discrepancy highlights a significant gap between the occurrence of structural failures and the use of rigorous, model-based investigation methods. The review shows a clear shift from single-method approaches (e.g., Fault Tree Analysis (FTA) or Finite Element Analysis (FEA)) to hybrid, integrated models that combine computational, qualitative and data-driven techniques. This reflects the growing recognition of structural failures as socio-technical phenomena that require multi-methodological analysis. A key contribution is the development of a strategic framework that classifies models by complexity, data requirements and cost based on patterns observed across the reviewed papers. This framework can be used as a practical decision support tool for researchers and practitioners to select the right model for the context and highlight the strengths and limitations of the existing approaches. The findings show that the future of structural safety is not about one single “best” model but about intelligent integration of complementary context-specific methods. This review will inform future practice by showing how different models can be combined to improve the depth, accuracy and applicability of structural failure investigations. Full article