Search Results (79)

This study presents the design and fabrication of a glass fiber–poplar veneer composite plate, investigating how varying interlayer configurations of glass fiber (single- and double-layer) and the arrangement of poplar veneer layers (odd and even) impact the mechanical and thermal insulation characteristics of these composite plates. Compared to plywood made from natural wood, glass fiber significantly improved the properties of fast-growing poplar plywood. The highest impact strength increased by 3.62 times, while the flexural strength increased by 26.22% and the tensile strength by 29.66%. The thermal diffusion coefficient of the experimental group decreased by 40.74%, indicating better insulation. Interestingly, single-layer glass fiber is superior to a double-layer structure in terms of thermal insulation. An optimal interlayer structure was identified, comprising one veneer layer between two layers of glass fiber cloth, repeated three times. Abaqus 2019 was used for finite element analysis (FEA). The simulation results agree with the experimental data to within 5%. These findings confirm the importance of structural configuration in determining the properties of composite materials, providing a theoretical basis for the structural design of fiber–reinforced composite materials. Full article

During the sintering process of NdFeB bulks, temperature changes and significant temperature differences between the bulk interior and the surface region will produce high residual stress. Temperature field and stress field prediction during the sintering process is one of the key techniques for analyzing residual stress. Therefore, the sintering process simulation and residual stress prediction of NdFeB bulks under different sintering temperatures were conducted based on the modified Drucker–Prager cap (DPC) model in ABAQUS (ABAQUS 2024). The calculated field cloud charts were analyzed against the microstructure of the bulks observed by scanning electron microscope (SEM). The finite element analysis (FEA) results of the sintering process and the residual stress show good agreement with SEM morphologies, which validates the accuracy and predictability of the model. The results indicate that cracks predominantly formed in edge regions. As the sintering temperature increased, longitudinal compressive stress at the edge of the cross-section transitioned into tensile stress. These results indicate that the developed simulation framework effectively identifies crack-prone areas, enabling data-driven optimization to reduce experimental trial-and-error costs in engineering applications. Full article

The deterioration of aging masonry structures poses significant challenges to structural safety, particularly under seismic loading. In response to the growing need for effective retrofitting solutions, stiff-type polyurea (STPU) has emerged as a promising material due to its high tensile strength, durability, and rapid application characteristics. This study investigates the seismic performance of masonry walls retrofitted with STPU through both shaking table tests and finite element analysis (FEA). Three types of specimens (non-strengthened, STPU-strengthened, and STPU + GFRP-strengthened walls) were subjected to out-of-plane seismic loading with additional mass loading to simulate real-world conditions. Experimental results demonstrated that STPU significantly improved the ductility and seismic resistance of masonry walls, with the STPU + GFRP hybrid system showing the highest performance. A simplified micro-model using ABAQUS successfully captured the primary failure modes and load-bearing behavior observed in the experiments. Furthermore, a parametric study on STPU thickness identified 2 mm as the most efficient thickness considering both strengthening effect and material economy. These findings confirm the effectiveness of STPU as a retrofitting material and demonstrate the reliability of the proposed numerical modeling approach in predicting the seismic response of retrofitted masonry structures. Full article

Composite pressure vessels offer significant advantages over traditional metal-lined designs due to their high strength-to-weight ratio, corrosion resistance, and design flexibility. This study investigates the structural design, winding process, finite element analysis, and experimental validation of a glass fiber-reinforced composite low-pressure vessel. A high-density polyethylene (HDPE) liner was designed with a nominal thickness of 1.5 mm and manufactured via blow molding. The optimal blow-up ratio was determined as 2:1, yielding a wall thickness distribution between 1.39 mm and 2.00 mm under a forming pressure of 6 bar. The filament winding process was simulated using CADWIND software (version 10.2), resulting in a three-layer winding scheme consisting of two helical layers (19.38° winding angle) and one hoop layer (89.14°). The calculated thickness of the composite winding layer was 0.375 mm, and the coverage rate reached 107%. Finite element analysis, conducted using Abaqus, revealed that stress concentrations occurred at the knuckle region connecting the dome and the cylindrical body. The vessel was predicted to fail at an internal pressure of 5.00 MPa, primarily due to fiber breakage initiated at the polar transition. Experimental hydrostatic burst tests validated the simulation, with the vessel exhibiting failure at an average pressure of 5.06 MPa, resulting in an error margin of only 1.2%. Comparative tests on vessels without adhesive sealing at the head showed early failure at 2.46 MPa, highlighting the importance of head sealing on vessel integrity. Scanning electron microscopy (SEM) analysis confirmed strong fiber–matrix adhesion and ductile fracture characteristics. The close agreement between the simulation and experimental results demonstrates the reliability of the proposed design methodology and validates the use of CADWIND and FEA in predicting the structural performance of composite pressure vessels. Full article

Fiber-reinforced polymer (FRP) composites are widely utilized in aerospace and shipbuilding due to their outstanding mechanical properties and lightweight nature. During prolonged service, the mechanical performance of composite bolted joints has drawn increasing attention. This study integrates experimental, theoretical, and numerical methods to simulate compressive creep and clarify preload relaxation mechanisms in these joints. A non-stationary Burgers model is proposed to describe the compressive creep behavior of FRP composites and metals, implemented in ABAQUS, which improves fitting accuracy by approximately 10% in R² compared to the classical model. Two types of creep tests were conducted to examine the effects of initial load and material type on creep behavior, with model accuracy validated against experimental data. Finite element analysis (FEA) was further employed to assess the impact of localized loading and structural parameters on strain. The results demonstrate that the viscoelastic behavior of materials is the dominant factor contributing to preload relaxation in composite bolted joints. Under localized loading conditions, the maximum creep strain can be reduced by more than 60%, effectively mitigating preload loss. This study provides a robust framework for predicting preload relaxation, offering valuable insights for composite bolted joint design. Full article

This paper introduces an efficient and automated computational framework integrating Python scripting with Abaqus finite element analysis (FEA) to investigate the structural behavior of long free-spanning submarine pipelines equipped with buoyancy modules. A comprehensive parametric study was conducted, involving 1260 free-spanning submarine pipeline models, and was successfully performed with a wide range of parameters, including the length ($l_p=$ 100, 200, and 300 m), radius ($r_p=$ 0.3, 0.4, and 0.5 m), thickness, type of fluid, type of support, load ratio ($LR=$ 0.2, 0.4, 0.6, 0.8, and 1), and number of buoyancy modules ($n=$ 0, 1, 2, 3, 5, 7, and 9) with its length $(l_b=1/10·l_p)$. The study included a verification process, providing a verification of the presented framework. The results demonstrate excellent agreement with analytical and numerical solutions, validating the accuracy and robustness of the proposed framework. The analysis indicates that pipeline deformation and natural frequency are highly sensitive to variations in buoyancy arrangements, pipeline geometry, and load conditions, whereas the normalized mode shapes remain largely unaffected. Practical implications include the ability to rapidly optimize buoyancy module placements, reducing resonance risks from vortex-induced vibrations (VIVs), thus enhancing the preliminary design efficiency and pipeline safety. The developed approach advances existing methods by significantly reducing the computational complexity and enabling extensive parametric analyses, making it a valuable tool for designing stable, cost-effective offshore pipeline systems. Full article

Steel structures subjected to earthquakes or extreme cyclic loadings may undergo extensive damage and fractures due to ultra-low-cycle fatigue (ULCF). Although assessments of damage initiation and evolution parameters have been carried out for some steels exposed to low-cycle fatigue, so far, these parameters for structural steels exposed to ULCF have neither been sufficiently studied nor quantified. Accordingly, this paper provides the results of finite element analysis (FEA) concerning the ULCF behaviors of S355 and S690 steel specimens. Calibration of the damage parameters is performed in SIMULIA Abaqus 6.11 FEA software using a direct cyclic algorithm and available experimental data. Kliman’s model for the hysteresis energy of cyclic loading is used to analytically verify the damage parameters. In addition, available experimental data were obtained from cyclic axial strain tests on S355 and S690 steel specimens according to the ASTM International standard E606/E606M-21. Finally, the non-linear Chaboche–Lemaitre (C–L) combined isotropic–kinematic hardening model is used for the characterization of the ULCF behavior of S355 steel in a simple cylindrical bar. It is found that the two damage initiation parameters are 5.0 and −0.8, the first damage initiation parameter is dominant when modeling the number of cycles to failure, and the second damage initiation parameter is a material constant. Full article

Aim: Class II Division I malocclusion poses significant challenges in orthodontics. The combination of a Herbst appliance and miniscrew anchorage emerged as a practical solution to improve skeletal and dental outcomes. This study employed finite element analysis to evaluate the biomechanical effects of a miniscrew-supported Herbst appliance on mandibular advancement and dentition movement. Methods: High-definition CBCT scans captured the maxilla and mandible’s detailed dental anatomy. The scans were stored in DICOM format for seamless integration with Mimics software (Mimics Innovation Suite research version 21.0, Materialise NV, Leuven, Belgium) for 3D reconstruction and model refinement. The appliance, designed with a maxillary fixed palatal arch and mandibular acrylic splint connected by telescoping rods, incorporated titanium TADs and elastic chains. STL models were optimized in Geomagic x Design for finite element analysis in Abaqus, assigning validated mechanical properties for materials. Tetrahedral meshing and realistic boundary conditions simulated biomechanical interactions. Tetrahedral C3D4 elements were used for meshing, ensuring a balance between computational efficiency and detailed anatomical representation. Tetrahedral meshing and realistic boundary conditions simulated biomechanical interactions. Dynamic simulations in CATIA evaluated mandibular movement. FEA analyzed displacement across dentoalveolar structures along the X, Y, and Z axes to assess treatment efficacy and biomechanical stability. Results: The Z displacement analysis revealed that the incisal edges of the lower central, lateral, and canines shifted lingually by 0.41, 0.4, and 0.47 mm, respectively. Additionally, the apices of the lower central, lateral, and canines displaced backwards by 0.05 mm, 0.05 mm, and 0.07 mm, respectively. Conclusions: The appliance facilitated mandibular advancement, bodily retracted the lower incisors, well-controlled the upper ones, and mesial-tipped the upper posterior teeth. In contrast with traditional functional appliances, it caused the lower anterior teeth to move backwards, while skeletal anchorage overcame some shortcomings of nonsurgical treatments. This method might be a good treatment option for growing skeletal Class II patients. Full article

Reinforced Concrete (RC) barriers are used for different purposes in the highway inventory. An important purpose is the use of concrete barriers to act as railing that protects bridge piers against vehicular collision force (VCF). Therefore, these barriers are designed to absorb the collision energy and/or redirect the vehicle away from the parts being protected. Accurate estimation of the capacity of RC barriers during crash events is an important consideration in their design and placement. The American Association of State Highway and Transportation Officials (AASHTO) considers yield line analysis (YLA) with the V-shape failure pattern to predict the barrier capacity. AASHTO’s analysis method involves some assumptions that are intended to simplify the analysis process. Some of these assumptions have been shown to underestimate the actual barrier capacity and might disqualify many existing RC barriers from acting as intervening structures due to structural inadequacy. Many researchers have proposed alternative failure patterns and methodologies in an attempt to better predict the capacity of RC barriers. This research shows that AASHTO’s YLA, with the current V-shape failure pattern, can be improved and still predict the barrier capacity when some of the simplifying assumptions are eliminated. Also, the research presents an alternative innovative truss analogy model to predict the capacity of RC barriers. The results of the improved YLA and the proposed truss model are validated by finite element analysis (FEA) using Abaqus. The results of this research will help structural engineers in the highway industry to initially design new barriers for the intended capacity as well as estimate the capacity of existing ones. Full article

This study aims to evaluate the stress distribution of polyetheretherketone (PEEK) and high noble alloy materials in a detailed 3D model of a central incisor using finite element analysis (FEA). A comprehensive 3D model incorporated the crown, crown cement, post and core, post cement, central incisor root, periodontal ligament (PDL), and bone. The PEEK and high noble alloy material properties were input into the model, and the FEA was performed using ABAQUS software. The results showed that while the stresses on the bone, root, and crown increased slightly with the PEEK compared to the high noble alloy, the difference was minimal and attributed to the PEEK’s reduced stiffness. This led to a higher load transfer to surrounding regions around the post. The factor of safety decreased from 16 to 10 when using PEEK, but this reduction was still within acceptable limits and reduced stress-shielding effects. In conclusion, while there was no significant difference in stress magnitudes and distributions between the PEEK and high noble alloys, the PEEK exhibited superior stress-shielding properties, which may offer an advantage in preserving the underlying tooth structure in post and core restorations. Full article

This study investigates the bending performance of web-embedded double inverted T-shaped steel–concrete composite beams (WDTSCBs) through experimental testing and finite element analysis (FEA). A novel composite beam structure was developed, where double inverted T-shaped steel beams are interconnected by slotted web plates and embedded in concrete flanges, aiming to enhance load-bearing capacity and ductility. Four WDTSCB specimens, utilizing C40 concrete and Q345qB steel, were tested under static loading to analyze failure modes, load-deflection behavior, and crack development. The experimental results were validated by FEA in ABAQUS, achieving an error margin of less than 5%. The findings indicate that WDTSCBs exhibit superior flexural performance compared to traditional composite beams, with higher bending resistance and reduced steel consumption. These results provide valuable insights into the design and optimization of steel–concrete composite structures, promoting their application in civil engineering. Full article

The rapid development of AI (artificial intelligence), sensor technology, high-speed Internet, and cloud computing has demonstrated the potential of data-driven approaches in structural health monitoring (SHM) within the field of structural engineering. Algorithms based on machine learning (ML) models are capable of discerning intricate structural behavioral patterns from real-time data gathered by sensors, thereby offering solutions to engineering quandaries in structural mechanics and SHM. This study presents an innovative approach based on AI and a fiber-reinforced polymer (FRP) double-helix sensor system for the prediction of forces acting on steel tube members in offshore wind turbine support systems; this enables structural health monitoring of the support system. The steel tube as the transitional member and the FRP double helix-sensor system were initially modeled in three dimensions using ABAQUS finite element software. Subsequently, the data obtained from the finite element analysis (FEA) were inputted into a fully connected neural network (FCNN) model, with the objective of establishing a nonlinear mapping relationship between the inputs (strain) and the outputs (reaction force). In the FCNN model, the impact of the number of input variables on the model’s predictive performance is examined through cross-comparison of different combinations and positions of the six sets of input variables. And based on an evaluation of engineering costs and the number of strain sensors, a series of potential combinations of variables are identified for further optimization. Furthermore, the potential variable combinations were optimized using a convolutional neural network (CNN) model, resulting in optimal input variable combinations that achieved the accuracy level of more input variable combinations with fewer sensors. This not only improves the prediction performance of the model but also effectively controls the engineering cost. The model performance was evaluated using several metrics, including R², MSE, MAE, and SMAPE. The results demonstrated that the CNN model exhibited notable advantages in terms of fitting accuracy and computational efficiency when confronted with a limited data set. To provide further support for practical applications, an interactive graphical user interface (GUI)-based sensor-coupled mechanical prediction system for steel tubes was developed. This system enables engineers to predict the member forces of steel tubes in real time, thereby enhancing the efficiency and accuracy of SHM for offshore wind turbine support systems. Full article

Fibre-reinforced polymers based on natural fibers, such as flax fibers, exhibit pronounced nonlinear orthotropic material behavior. This presents a significant challenge in finite element analysis (FEA) simulations, as the nonlinear constitutive models available in commercial FEA tools are difficult to apply and fail to capture all the material’s specific characteristics. Relying on initial or reduced secant moduli in linear quasi-static analyses of deformations or stress states can result in inaccurate outcomes and overly optimistic strength predictions, particularly in compression-dominated cases. However, with appropriate modifications, classical laminate theory (CLT) can be adapted for nonlinear analysis. This involves iteratively updating the components of the stiffness matrix for the unidirectional (UD) ply during the calculation process based on the current strain state and stress interactions. This study presents and discusses a computational algorithm for the FEA software ABAQUS/CAE 2019, which incorporates material-related orthotropic nonlinearities and stress-dependent interactions within the CLT framework. The algorithm represents a single-scale material model at the meso level (UD ply) and is based on the concept of orthotropic elasto-damage within the framework of continuum damage mechanics (CDM) theory. Numerical implementation is achieved through a user-defined field (USDFLD) subroutine, accompanied by a pre-processing Python script for managing experimental data, computing data fields, and calculating parameters. As shown below, this type of implementation appears justified compared to a user material subroutine (UMAT) subroutine in terms of computational efficiency and practicality. Full article

This study investigated the optimal shape of glue-laminated timber beams using an analytical model of a slender beam, taking into account the anisotropy of its strength properties as well as boundary conditions at the oblique bottom face of the beam. A control theory problem was formulated in order to optimize the shape of the modeled beam. Two optimization tasks were considered: minimizing material usage ($V_{min}$) for a fixed load-carrying capacity (LCC) of the beam and maximizing load-bearing capacity ($Q_{max}$) for a given volume of the beam. The optimal solution was found using Pontryagin’s maximum principle (PMP). Optimal shapes were determined using Dircol v. 2.1 software and then adjusted according to a 3D finite element analysis (FEA) performed in Abaqus. The final shapes obtained through this procedure were used in the CNC-based production of three types of nine beams: three reference rectangular beams, three $V_{min}$ beams, and three $Q_{max}$ beams. All specimens were subjected to a four-point bending test. The experimental results were contrasted with theoretical assumptions. Optimization reduced material usage by ca. 12.9% while preserving approximately the same LCC. The maximization of LCC was found to be rather unsuccessful due to the significant dependence of the beams’ response on the highly variable mechanical properties of GLT. Full article

Purpose: The effectiveness of the customised solutions compared to the conventional ones and the emergence of advanced production technologies, such as Additive Manufacturing (AM) techniques, strengthened the trend towards an enhanced individualization of the clinical treatments. In the present research, the value of topological optimisation (TO) in the manufacturing process of tailor-made orthopaedic appliance (upper-limb orthosis) was analysed. Methodology: From the morphology of a patient’s arm, orthotic models were developed. Nonparametric optimization (Simulia Tosca) was performed, based on the Finite Element Analysis (FEA) program (Abaqus), and contributed to the development of TO orthotic models with diverse levels of volume reduction fraction. The modelling and manufacturing framework for customising orthotic solutions was evaluated with a discussion on the feasibility of lightweight and high-performance products, encompassing production time and cost. Pilot products were produced with a Material Extrusion (MEX) printer. Findings: TO proved to be a practical and valuable approach for the advanced customisation of orthopaedic devices, offering lightweight solutions able to withstand stresses also during patient rehabilitation and remission. From the rapid prototyping perspective, specific strategies must be adopted to prevent the escalation of production costs and time. Originality: The research delves into the overall benefit of implementing an advanced modelling technique within the context of manufacturing highly customised orthoses, analysing how TO activity impacts the rapid prototyping process. Beyond product evaluation, the analysis explores broader implications, including the assessment of feasibility and the development of strategies for integrating the approach into clinical workflows and hospital settings. Full article