Band 12, Heft 1

This article presents for the very first time a layerwise bending analytical solution for cross-ply laminated composite plates with clamped boundary conditions at all edges. The displacement field is implemented within the framework of the Carrera unified formulation at a layer level by employing Legendre polynomials. The governing equations are obtained by using the principle of virtual displacements statement. This work utilizes the boundary-discontinuous double Fourier series to provide analytical solutions. The high accuracy of the proposed solution is demonstrated by comparing the results with three-dimensional finite-element model (FEM) solutions of multilayered and sandwich plates for various side-to-thickness ratios. In conclusion, the highly accurate proposed solution might be used as a benchmark problem for new analytical or FEMs.

This study addresses the problem of thermoelastic interaction in functionally graded isotropic unbounded media owing to a timed pulse within the framework of generalized thermoelastic theory without energy dissipation (TEWOED). Functionally graded material (FGM, or material with spatially variable material characteristics) has its governing equations for the generalized thermoelastic model without energy dissipation (GNII) developed. These formulations are expressed in terms of Laplace transforms. The analytical solutions in the transform’s domain are obtained through the eigenvalues technique. The Laplace transforms are inversed using numerical methods. Finally, the acquired data are visually illustrated to illustrate how inhomogeneity, laser intensity, and laser pulse length affect displacement, temperature, and stress.

This article introduces a unique analytical solution with a layerwise approach for cross-ply laminated composite cylindrical and doubly curved panels with clamped boundary conditions at all four edges. Under a layerwise (LW) description, from lower- to higher-order models based on the Carrera unified formulation are built with Legendre polynomials. The strong-form governing equations are obtained by employing the principle of virtual displacements displacement-based statement. The boundary discontinuous Fourier-based method is employed to yield purely analytical solutions. The high accuracy and efficiency of our proposed methodology are evaluated by comparing the results against those from the 3D finite element method and the literature for various side-to-thickness and radius-to-depth ratios. As a conclusion, the numerical results presented can be used as a benchmark for future comparative analyses and finite elements.

A visual scripting approach for limit analysis of masonry walls subjected to out-of-plane loads is proposed. To this aim, within a visual scripting framework, an interactive CAD representation of the structure and of the acting loads, boundary conditions, and restraints is coupled with an optimization algorithm to calculate the collapse load multiplier and visualize the related predicted collapse mechanism. The proposed approach can be useful for practical purposes, indeed it allows us to quickly identify the key factors that influence the structural response and, through the tuning of some input data, can furnish some hints for design purposes. The effectiveness of the promoted tool is verified by application to eight well-known benchmark cases.

The transient response of thermoelastic materials subjected to a time-decaying thermal field is presented in this article using a nonlinear analysis. The basic equations provided are based on a generalized thermoelastic model under changing thermal conductivity, which is incorporated into the formulations. This problem is solved using the finite-element techniques instead of the Kirchhoff transforms since solving non-linear equations is quite difficult. Laplace transformation and the eigenvalue approaches are used to solve the problems in the linear context of the Kirchhoff transforms. The study investigates and compares the impact of varying thermal conductivity both with and without employing Kirchhoff’s transform. The numerical outputs are graphically shown to display the displacement, temperature, and stress variations.

The present study used analytical and numerical methods to conduction works in functional graded material fin that is exposed to progressive boundary cooling and heating. The fin length was chosen as a direction to vary thermal characteristic in functionally graded material, and the physical properties were ascertained by the linear model. In heat sink, two approximation analytical techniques are employed to evaluated the thermal performance: one based on a mean value problem and the other strategy based on principle of the equivalent qualities. ANSYS APD’s numerical solution was based on a stepwise modification of characteristics. The outcomes indicated that the thermal conductivity ratio significantly influences temperature levels, with the terminal temperature levels of the functionally graded fin varying exponentially in relation to the thermal conductivity ratio. The influence of material index begins with the length of functionally graded material-fin where the fin’s terminus experiences the largest effect. A 6.756% is the maximum absolute error between numerical and analytical findings, which indicating a strong concordance between the two analysis methods.

This study explores the relationship between the variable nonlocal parameter and material variations in functionally graded (FG) nanobeams incorporating the influence of unsteady aero thermal and magnetic load defined by the first-order Piston theory. The governing equations of FG Euler nanobeams are derived using Eringen’s nonlocal elasticity theory. These equations are then numerically tested using the Bernstein-based Rayleigh-Ritz method. A comparison with previously published results is conducted to validate the accuracy of the findings. Additionally, the study investigates the effects of nonlocal ceramic, nonlocal metal parameters, Mach number, and aerodynamic force on various physical parameters of FG nanobeam.

The aim of this work is to investigate gallium arsenide, a particular kind of semiconductor. The study employs a three-layer asymmetric slab waveguide structure, where a thin gallium arsenide (GaAs) film is deposited on a glass substrate, and above the film is a dielectric cladding, such as air. To enable complete internal reflection at the interfaces, the guiding slab’s index of refraction has to be greater than that of the cover material (cladding) or the substrate material. Further investigated are the effects of the thickness of GaAs on transverse electric/transverse magnetic (TE/TM) propagation modes typically. Every method was shown with specific settings. The thickness of GaAs affects the number of TE/TM modes. Cut-off wavenumber and attenuation decrease for a particular applied wavelength (0.6328 µm) due to decreasing propagation wavenumber. Simulation findings clearly reveal that the basic mode has the biggest incidence angle and lowest penetration depth; the highest mode has the incidence angle very near the critical angle and the best penetration depth. The design of integrated optical devices depends on optical waveguides, which calls for consistent and accurate findings for defining the waveguide’s properties prior to manufacturing.

The possibility of damage caused by explosive loading in above-ground tanks due to not being covered is much higher compared to buried and semi-buried concrete and steel tanks. In order to evaluate the real behavior of above-ground tanks, it is necessary to pay attention to fluid and structure interaction. Therefore, investigating the behavior of above-ground tanks under the blast load, taking into account the effects of fluid-structure interaction is the main goal of the study. For this purpose, the main variables are the amount of fluid in the tank (empty, half full, and full) and the distribution of fluid pressure on the tank (uniform and nonuniform pressure). Also, the investigated responses include maximum von Mises stress, maximum displacement created in the tank, kinetic energy, and failure index. The results show that considering the tank as empty of fluid, increased the responses of maximum stress, maximum displacement, kinetic energy, and failure index by 18.1, 31.2, 4.1, and 17%, respectively. Also, filling the tank with fluid has caused a decrease of 41, 90, 8.9, and 15.4% in the responses of maximum distributed stress, maximum displacement, kinetic energy, and failure index of the tank, respectively. Other results show that the nonuniform distribution of fluid pressure in the tank increases the maximum responses of stress and failure index in the tank by 35.6 and 2.5%, respectively. In this condition, the maximum responses of displacement and kinetic energy decrease by 84.3 and 4.3%, respectively.

Grounding is an accident on the ship that can hit the bottom ship, propeller, rudder, and other ship structure. Notch is a defect often appearing in ship structures, aircraft structures, bridges, welded joints, and even microstructures. The most formed notch shape is a notch with a V-like shape called a V-notch. The present study relies on the finite element approach to analyze the impact of the V-notch defect on the grounding penetration simulation on a stiffened bottom plate. This study models 28 distinct scenarios distinguished by the quantity, size, and distance between V-notches. Study outputs in reaction force, resistance, and plate deformation due to penetration, stress concentration, and penetration depth of grounding impact on the stiffened bottom plate are obtained using dynamic explicit simulation in the form of penetration. The outcomes of the numerical simulation demonstrate that the existence of V-notch defects causes stress concentration, reducing the plate structure’s resistance and allowable penetration. The plate with one V-notch defect can reduce the resistance to 29.7% of the resistance of the plate without defects. Besides that, the resistance of the plate with two defects drops by only 5.2%, while when there are three defects simultaneously on the stiffener plate, the plate resistance is reduced by 31.4%. This research shows that the number of V-notches does not determine resistance in a plate, but the position of the V-notch on the plate is close to the penetration area, which is about 100 mm from the center of the plate. V-notch defects with smaller opening angles reduce resistance by 34.38% compared to larger opening angles, which only reduce resistance by 29.77%. Therefore, reducing the strength of the ship in grounding will increase the possibility of losing ship buoyancy, cargo leaks, engine and electrical failure, and loss of propulsion.

This work presents an analytical derivation for the stress and deformation formulations under combined mechanical and thermal loading in rectangular functionally graded curved beams. The mechanical load consists of a double couple, while the thermal load corresponds to a steady-state temperature distribution. Using Timoshenko beam theory and thermo-elastic theory, the governing equations incorporate an exponential material gradient in the radial direction, assuming a constant Poisson’s ratio. The Mathematica software was utilized to evaluate the stress and deformation formulations for the thermo-mechanical analysis. Meanwhile, Matlab software was used to perform the results. The results of normalized stresses (including radial, tangential, and von Mises components) and deformations are presented at different variations of temperatures for two different materials that are plotted. The results for the two considered FGM materials, Aluminum/steel and Ti-6Al-4V/ZrO 2 are compared, demonstrating lower stresses for Ti-6Al-4V/ZrO 2 under identical conditions. The study highlights the influence of temperature and material gradients that affect stress and deformation, with strong agreement between analytical results and finite element analysis (ANSYS simulations), validated through MATLAB plots.

Electricity consumption is expected to increase significantly by 2050. It is essential to ensure that as the increase occurs, there is also a corresponding increase in the proportion of renewable energy sources in the electricity supply. Wind energy has great potential as a promising source of renewable energy. One alternative method for harvesting wind energy is the use of Savonius turbines, which can help expand the collaboration between renewable energy and conventional resources. The critical parts in deploying the Savonius are the consideration of the curved geometrical factor. Thus, this study aims to assess how the geometrical factors of the Savonius turbine affect its performance, and the findings from this research can offer valuable insights for designing an optimal Savonius rotor that aligns with specific requirements. As part of geometrical variations, three different shapes are being modeled and analyzed: one with a phase-shift angle (PSA) of 0°, another with 25°, and a third with 35°. To produce the calculation results, the research employed advanced three-dimensional modeling techniques and the computational fluid dynamics (CFD) method, considering steady conditions and the shear stress transport model. A factorial design analysis was then conducted based on the obtained CFD results to validate the significance of the data research results regarding the impact of these factors on performance. Based on the summarized result trends, the type-1 rotor, with a PSA of 25°, exhibits excellent CPmax performance, achieving a value of 0.32. The results of the factorial design approach analysis indicate that the blade shape, tip-speed ratio, and PSA factors have a significant influence on the performance of the Savonius Rotor.

Friction stir processing (FSP) has emerged as an effective technique for enhancing the mechanical and microstructural properties of metal matrix composites. This study investigates the influence of FSP parameters on the mechanical characteristics and microstructure of AZ31B magnesium alloy reinforced with silicon carbide particles of size APS < 80 nm. The method employed here is a hole method for reinforcement and designed with an L9 orthogonal array to analyze the effects of tool geometry, rotational speed, traverse speed, and hole diameter. The experimental findings indicate that a cylindrical threaded tool pin profile, a 0.8-mm hole diameter, a rotational speed of 765 revolutions per minute, and a traverse speed of 31.5 mm/min resulted in the most optimal combination of mechanical properties, including improved tensile strength, micro-hardness, and elongation. Microstructural analysis revealed a uniform distribution of SiC particles, leading to grain refinement and enhanced material performance. These results demonstrate that FSP is a sustainable approach for fabricating high-performance magnesium-based composites, making them suitable for applications in aerospace, automotive, and biomedical industries.

This comprehensive study meticulously analyzes the hydrodynamic performance of various patrol boat designs to enhance maritime security in the Arafura Sea, Indonesia. We evaluated three hull types – monohull, catamaran, and trimaran – based on resistance, stability, seakeeping, and passenger comfort. The study generated nine hull variations using regression analysis. The multi-attribute decision making method and sensitivity analysis were applied to determine the optimal design. The results, a testament to our thorough approach, showed that Catamaran Hull C had the best performance, with the lowest resistance, better stability, and improved seakeeping characteristics. This design is recommended for patrol operations in the Arafura Sea, supporting maritime security and the achievement of the Sustainable Development Goals.

In this work, an enhanced MITC3+ approach enriched by a constant in-plane strain correction is proposed in the analysis of functionally graded (FG) porous plates. The approach involves formulating the corrected in-plane strain field through the utilization of corrected nodal derivatives in the concept of discrete divergence consistency (DDC). The DDC for the in-plane strain field is obtained through the orthogonality condition derived from the three-field variational principle (Hu-Washizu), which arises from the difference between resultant in-plane stress and in-plane strain. In carefully examining the static analysis of the FG porous plate with different elements, our investigation delves into the influence of length-to-thickness ratios, power-law indices, and porosity distributions. This comprehensive examination aims to illuminate their combined influence on the numerical outcomes. The proposed approach demonstrates superior performance in addressing FG shell problems, outperforming the original MITC3+ method.

This study aims to examine the development of research on seaplanes and determine the innovations that have been achieved or researched. To better serve the demands of real aircraft designers, this research presented a new process for creating seaplane designs. Combining historical seaplane data with current ship and aircraft design data resulted in a new preliminary seaplane concept design. Another benefit of this design approach is transforming an existing landplane into a seaplane by adding a floating device that satisfies seaplane conversion standards. Enhancing hydrodynamic performance was the addition of a trimaran design. A retractable float device was employed to add drag reduction during flying. The trimaran idea provided superior hydrostatic stability and increased water speed, while the floats’ retractable design decreased aerodynamic drag for improved flying performance. A computational design framework is also created to assess the efficacy and performance of hydrofoils for amphibious aircraft, with a particular emphasis on water take-off performance. For validation, a comparison is made between the numerical simulations and the experiment results. The results of this study show that seaplane research over the past decade has produced several innovations, from general to detailed designs. Seaplane also has the potential to be developed in the coming years.

The propeller shaft inclination angle is one of the critical parameters influencing the speed of a fishing boat. This study assesses how the propeller shaft inclination angle impacts the speed of composite fishing boats through experimental and numerical analyses. The model used for testing is a scaled-down version of a 24.0 m × 6.5 m × 3.5 m fishing boat, constructed at a 1:12 scale using composite materials (polyester resin and fiberglass). The model allows for the propeller shaft angle adjustment from 0° to 15°. The model was tested at the design speed of 2.9 knots to measure the vessel’s speed corresponding to various inclination angles. Additional tests were conducted at lower (2.31 knots) and higher (3.46 knots) speeds to validate the results. The model was also simulated using computational fluid dynamics (CFD) software to compare and assess the reliability of the experimental results. Subsequently, the CFD software was employed to simulate the actual vessel and evaluate its performance. The results of the experiments and simulations demonstrate significant variations in vessel speed as the inclination angle increases from 0° to 15°. The maximum speed was achieved when the propeller shaft inclination angle ranged between 6° and 7° (reaching 3.05 knots). The vessel speed decreased substantially when the inclination angle increased from 9° to 15°. The speed variation patterns for the 2.31 knot and 2.9 knot cases were similar, whereas the 3.46 knot case exhibited notable differences. The optimal propeller shaft inclination angle range for achieving high speeds for the studied vessel lies between 3° and 8°.

Design optimization of a liquefied natural gas (LNG) ISO tank is essential to ensure structural integrity while minimizing weight. This approach enables the identification of efficient material distributions under critical loading conditions, enhancing safety, compliance with ISO 1496 standards, and overall transport efficiency without compromising strength. This study proposes a topology optimization for the Bakelite support structure of a 40 ft LNG ISO tank that balances structural strength and weight efficiency. The optimization process incorporates two main strategies: strain energy minimization and mass retain, defined as the objective function and constrained within a 90–50% mass retain range. To ensure structural integrity and regulatory compliance, the resulting designs are evaluated under the ISO 1496 standard loading scenarios, including lifting, stacking, and racking. Initial mesh convergence study of the proposed finite element analysis model shows optimum mesh selection with optimum computational time. The topology optimization results with mass retain ranging from 90 to 50% in all loading scenarios achieved a substantial weight reduction in the Bakelite support, between 4.81 and 81.41%, by eliminating the Bakelite application in the middle support of the pressure vessel. The optimized Bakelite support slightly increases stress and deformation in both the pressure vessel and the Bakelite support, remaining within the standard criteria limits. The proposed optimization is promising in maintaining structural strength compliance with ISO 1496 standards.