The wind turbine tower is an important component of the system that collects wind energy. The tower is built as a series of tapered pipes with decreasing thickness upward, which makes the joint connections play a significant role in the global structural integrity of the tower. A tower failure may trigger a global failure, as it might be followed by the rotor’s collapse, resulting in significant losses in maintenance expenditure. This study investigates the collapse behavior of the wind turbine tower with and without a bolt joint. The tower response was analyzed using the Finite Element Method (FEM) implemented in ABAQUS. Initially, a benchmarking analysis was conducted to verify the simulation procedures. After verification, numerical simulations were performed for the selected case configurations to evaluate the tower’s behavior under combined axial compression, shear force, and bending moment. Numerical simulation results show that the torsional loading of Loading Case 2 (LC2) significantly reduces the Load Proportionality Factor (LPF), with Loading Case 1 (LC1) having an LPF of 2.89 and LC2 having an LPF of 1.39, resulting in a weakening effect of torque on stability. Meanwhile, Material Nonlinear Analysis (MNA) and Geometric and Material Nonlinear Analysis (GMNA), which account for material plasticity and geometric nonlinearity, provide more realistic predictions with LPFs of 1.89 and 1.24 for LC1 and 1.95 and 1.29 for LC2. In addition, bolt pretension improved stress redistribution and structural stability, resulting in a more uniform load transfer within the jointed system. Therefore, these results contribute to the design and optimization of tower structures, emphasizing the importance of considering both material and geometric nonlinearities, as well as bolt pretension, in structural analysis.
Excessive solar exposure can result in elevated temperatures on solar photovoltaic (PV) panels, therefore decreasing their efficiency. To address this issue, passive cooling techniques utilizing vortex generators (VGs) can be employed to maintain optimal thermal conditions for the solar panel. The current study presents a numerical analysis using computational fluid dynamics to analyze the impact of varying the aspect ratio of the delta winglet VGs on the cooling of a solar PV system as a preliminary study. The aspect ratio was modified by altering the base width of the delta winglet while maintaining fixed heights of 20 mm and 10 mm. The investigation focused on the Nusselt number, convective heat transfer coefficients, and flow visualization to evaluate the heat transfer characteristics. The proposed method has been validated against empirical correlation for the heat transfer coefficient and Nusselt number. The findings indicate that variations in aspect ratio significantly influence heat transfer performance. Notably, the highest increase in the Nusselt number was observed for an aspect ratio of 3.0, with a height of 20 mm and a width of 60 mm, yielding an enhancement of 58.57 %. Flow visualization revealed that the adjusted aspect ratio modifies the flow distribution, thereby generating vortices within the flow.
The article presents a novel analytical machine learning (ML)-based hybrid framework for studying vibration behavior of advanced composite cylindrical microshells based on butterfly-shaped auxetic cores and functionally graded triply periodic minimal surface (FG-TPMS) face layers reinforced using graphene platelet reinforcements (GPLRCs). The analytical framework combines first-order shear deformation theory (FSDT) with modified strain gradient theory (MSGT) to account for the effects of size that are present in microstructures. Hamilton’s concept is used to find dynamic governing equations, and Fourier series expansions are used to solve them analytically. The butterfly-shaped auxetic core signifies a notable improvement over traditional re-entrant auxetic designs, providing increased stiffness and greater structural stability while preserving negative Poisson’s ratio properties. The FG-TPMS face layers deliver optimal strength-to-weight ratios through mathematically engineered periodic structures, further enhanced by strategically positioned GPL reinforcements. An extreme gradient boosting (XGBoost) technique is designed and trained on a comprehensive dataset of 48,600 simulation points to enhance the analytical approach and facilitate swift design optimization. The collection includes essential design characteristics such as MSGT length scale parameters, TPMS pattern variations, butterfly-auxetic geometric ratios, GPL distribution patterns, porosity distributions, weight fractions, and porosity factors.
This research focuses on the size optimization of fuselage frame structures for Medium Altitude Long Endurance Unmanned Aerial Vehicle (MALE UAV), constructed from carbon fiber composites, to reduce mass while maintaining structural integrity. The optimization process utilizes finite element method (FEM) simulations and targets thickness and ply orientation angle variables. Constraints such as failure indices based on the Tsai-Hill criterion, displacement limits, and symmetry composite design requirements are strictly adhered to. The optimization process often results in the elimination of unnecessary layers, particularly middle laminates like layer 5, and adjusts fiber orientations, typically favoring 90° for outer layers and 0° or ±45° for middle layers, to improve stress distribution and load management. FEM simulations comparing the initial and final frame designs show mass reductions ranging from 10 to 11 % in certain frames. However, in some cases, mass remains unchanged, with only fiber orientations being modified to enhance performance. This size optimization not only reduces mass but also ensures that the structural performance meets strength and rigidity requirements under operational loads. The findings contribute to aerospace engineering by offering strategies that balance performance, reliability, and mass efficiency in composite material applications.
This study investigates the ultimate bending moment of box girders within ship structures, dissecting the impact of geometrical parameters, initial imperfections, and the direction of bending moment. Employing the Finite Element Method (FEM) analysis, this investigation navigates through the complex interplay among these variables to unravel profound insights into structural behavior. Initially, a comprehensive benchmarking analysis conducted to evaluate the accuracy of computational models against experimental data. The results demonstrated a high degree of precision, with discrepancies being limited to approximately 2 %. The examination of geometrical parameters unveils their significant role in shaping the structural integrity of box girders, shedding light on how variations in dimensions can influence the ultimate bending moment. Moreover, the study scrutinizes the effect of initial imperfections, recognizing their potential to trigger structural vulnerabilities and alter load-bearing capacities. The investigation reveals significant correlations between geometrical parameters and the ultimate bending moment. Increasing the span/bay ratio from 1 to 6 results in a 70 % decrease in the ultimate bending moment with a constant initial imperfection of 100 %. In contrast, raising the b/t ratio from 35 to 70 leads to a reduction of approximately 65 % in the ultimate bending moment at an imperfection of 250 %.
