https://ajme.aut.ac.ir/ AUT Journal of Mechanical Engineering en daily 1 Wed, 01 Apr 2026 00:00:00 +0330 Wed, 01 Apr 2026 00:00:00 +0330 https://ajme.aut.ac.ir/article_5897.html Cutting tools are subjected to severe wear during machining operations, especially when processing hard-to-machine materials. This wear primarily results from the intense friction and heat generated at the tool–chip–workpiece interfaces. To mitigate these effects and extend tool life, numerous strategies have been developed to modify the rake and flank surfaces of cutting tools. These include surface texturing and advanced coating techniques aimed at enhancing tribological properties, chemical stability, and resistance to mechanical stresses. This review provides a comprehensive analysis of such surface modification methods, highlighting their role in reducing friction, minimizing tool wear, and improving cutting efficiency. A detailed classification of cutting tool materials, such as ceramics, carbides, and polycrystalline cubic boron nitride used in recent studies for machining hard materials is presented. The paper also identifies current challenges and research gaps, particularly in the context of superalloy machining. Finally, it outlines promising future directions, including the development of functional tool surfaces, integration of data-driven optimization approaches, and the exploration of novel tool materials and geometries. The overarching aim is to promote sustainable, cost-effective, and high-performance machining practices aligned with modern manufacturing demands. https://ajme.aut.ac.ir/article_5971.html This review presents a comprehensive and critical evaluation of carbon-based and graphene-based thermal interface materials (TIMs) for advanced thermal management in electronic systems. Conventional TIMs typically exhibit thermal conductivities in the range of 0.1–10 W/m·K, limiting their effectiveness in high-power and miniaturized devices. In contrast, carbon-based TIMs demonstrate significantly enhanced performance, with carbon nanotube (CNT) composites achieving 8–12 W/m·K and graphene-based composites reaching up to 23.2 W/m·K at 60 wt% loading. We provide a detailed comparative analysis of CNT and graphene architectures, emphasizing their exceptional intrinsic thermal conductivities (~3000 W/m·K for CNTs and ~5000 W/m·K for graphene) and addressing practical challenges such as interfacial resistance, dispersion uniformity, and large-scale integration. The review synthesizes fabrication strategies, performance trends, and application-specific considerations, while outlining future directions including hybrid architectures, eco-friendly formulations, and cost-effective, scalable manufacturing techniques. By integrating quantitative comparisons and identifying critical research gaps, this work offers a roadmap for next-generation TIM development aimed at a high-power electronics, telecommunications, and computing systems, where efficient thermal management is essential for reliability, energy efficiency, and long-term operational performance. https://ajme.aut.ac.ir/article_5857.html This study examines transient natural convection (NC) heat transfer (HT) and entropy generation (Egen) in a square enclosure containing thermally stratified water. The model considers uniform heating at the bottom wall, stratified vertical walls, and a cooled top boundary. Governing equations are addressed through the finite volume (FV) method, with simulations performed across a range of Rayleigh numbers (Ra) from 100 to 5 × 10⁶, a fixed Prandtl number (Pr) of 7.01, for water. Various physical quantities were analyzed across the spectrum of Ra to capture the complex dynamics of convective flow. This encompasses streamline and isotherm plots, the temporal evolution of temperature, phase-space representations via limit cycles and limit points, along with spectral analysis, including the average Nusselt number (Nu), local entropy generation (El), and local Bejan number (Bel). The results reveal successive bifurcations with increasing Ra: a pitchfork bifurcation (Ra = 8 × 10³–10⁴) leads to symmetry breaking, a Hopf bifurcation (Ra = 2 × 10⁵–3 × 10⁵) induces periodic oscillations, and chaotic flow emerges at Ra = 10⁶–2 × 10⁶. The average Nusselt number at the bottom wall increases from 5.84 for Ra = 2 × 105 to 15.87 for Ra = 2 × 106, corresponding to a 171.75% enhancement in the HT. The numerical framework was validated by comparing it with existing numerical literature, confirming the results’ reliability. https://ajme.aut.ac.ir/article_5898.html This paper presents a comprehensive parametric analysis concentrated to the design of a novel low temperature hydrogen porous micro-reactor. The main important of this work is optimizing the water production process by a complete parametric description. In the analytical solution of this problem, the velocity profile is first determined by solving the momentum equation, and this result is then used in the energy and mass concentration equations to obtain thermal and mass parameters. The solution is achieved through a non-asymptotic solution that concurrently incorporates both mathematical and physical aspects, taking into account the matching conditions . Maximum variation of Nusselt number in the width of microchannel is observed for the alumina porous medium, with values of 58.70% and 67.69% respectively with 95% and 90% porosities. The rate of hydrogen to water conversion in alumina media is approximately 41% faster than titanium oxide and 67% faster than silicon carbide. The maximum variation of Sherwood number in the width of microchannel is observed for the silicon carbide porous medium, with values of 58.33% and 50.13% respectively with 95% and 90% porosities. As the porosity coefficients increase from 85% to 95% the variation rates of fluid and solid phase temperature is decreased from 78.01% to 45.09% and 65.92% to 35.09%. the porosity coefficient, the rate of hydrogen to water conversion is increased from 43.01 to 75.05%. https://ajme.aut.ac.ir/article_5837.html This study investigates the flow physics of a high-wing regional jet aircraft under stall conditions. The main aim of this research is to study the effects of nacelle-pylon configuration and trailing edge control surfaces on flow characteristics, particularly the formation of stall cells, during the takeoff and landing phases of the flight envelope. Oil flow visualization techniques were employed to conduct experiments in a low-speed subsonic wind-tunnel at low Reynolds numbers, with angles of attack ranging from 0° to 20°. The study also explored the influence of forced transition achieved by using trip strips, flow physics at different angles of attack, and two slotted trailing edge flaps with deflection angles of 15° and 40° on flow separation. Results from multiple wind-tunnel tests revealed the existence of mushroom-shaped structures, knowns as stall cells, on the wing surfaces of the typical jet aircraft. The size and strength of these structures increased by increment of the angles of attack. Additionally, the slotted flap effectively mitigated stall cell formation by injecting high-pressure flow through the slot and modifying the wing’s effective camber line. https://ajme.aut.ac.ir/article_5939.html The growing demand for sustainable energy highlights the need for efficient small-scale wind turbines, especially in urban areas with low wind speeds and limited space. This study experimentally examines aerodynamic augmentation effects on turbine performance using shrouds and tailored flanges. Four turbine configurations—a bare turbine, a turbine with a simple shroud, a shroud with a vertical flange, and a shroud with an improved curved flange—were 3D printed and tested in a controlled wind tunnel under realistic low- to moderate-speed urban wind conditions. Airflow velocity at the shroud throat and corresponding power output were measured across various wind speeds. Results show that both flange curvature and height significantly affect aerodynamic performance. The curved-flange design consistently increased throat velocity and turbine output, achieving up to a 32.3-fold power gain over the bare turbine at 5 m/s. At higher wind speeds, differences among augmented configurations decreased, yet the improved curved flange still delivered approximately 4.3 times the output of the bare turbine at 16.35 m/s. These findings emphasize the importance of outlet geometry in lowering startup thresholds, sustaining airflow acceleration, and maximizing energy capture. Overall, this study provides robust experimental evidence that shrouds with improved curved flanges significantly enhance small-scale urban wind turbine efficiency, offering a practical solution for low-wind energy harvesting and guiding future designs for improved performance across diverse wind regimes. https://ajme.aut.ac.ir/article_5798.html Thermal stresses in solid oxide fuel cells, caused by differential expansion during thermal cycling and coefficient of thermal expansion mismatches, lead to material degradation, cracking, voltage instability, and reduced reliability, hindering commercial viability. This study introduces a novel six-channel active cooling system for solid oxide fuel cells, aimed at lowering peak temperatures, improving thermal uniformity, and stabilizing voltage output. Using three dimensional numerical simulations with hydrogen/water vapor and oxygen/nitrogen as reactants, it systematically examines how cooling parameters such as flow rate, temperature, and flow configuration affect electrochemical performance. Key results demonstrate that co-current cooling (600 K, 1×10⁻⁶ kg/s) reduces peak temperature by 9% (to 1387 K) but at the cost of a 133% increase in temperature non-uniformity and a 55% voltage drop due to elevated overpotentials. Conversely, counter-current cooling (1000 K, same flow rate) achieves a more balanced performance, lowering peak temperature by 6% (to 1389.11 K) while reducing non-uniformity by 21.5% and increasing output voltage by 5.5% (0.2933 V). A critical finding is that excessive cooling (1×10⁻⁵ kg/s) leads to premature voltage collapse, with co-current flows failing at lower current densities (e.g., 9800 A/m² at 600 K) compared to counter-current configurations. This study pioneers an active cooling optimization framework for solid oxide fuel cells, demonstrating how precisely adjusted cooling parameters balance thermal control with electrochemical efficiency. https://ajme.aut.ac.ir/article_5940.html Polylactic acid (PLA), a biodegradable thermoplastic derived from renewable resources, has emerged as one of the most widely utilized materials in fused deposition modeling (FDM) due to its printability, cost-effectiveness, and environmental sustainability. Despite its popularity, PLA parts fabricated by FDM often suffer from reduced mechanical reliability as a result of anisotropy and processing variability. This study presents a comprehensive experimental and numerical investigation into the strain-rate-dependent mechanical behavior of FDM-printed PLA components, with particular emphasis on the influence of build orientation, raster angle, and infill pattern on tensile performance. ASTM D638 Type-V dog-bone specimens were fabricated using Ender 3 Pro and Xplorer 3D printers and tested at strain rates of 2 mm/s, 5 mm/s, and 10 mm/s on a Universal Testing Machine. Results revealed that tensile strength increases significantly with higher strain rates, showing improvements of up to 115%, though at the expense of ductility. Among orientations, on-edge samples exhibited the highest strength of 32.3 MPa, while raster angles aligned with the loading axis enhanced stress transfer and stiffness. Infill geometry further influenced energy absorption, with concentric patterns outperforming hexagonal arrangements. Numerical simulations conducted in Ansys and Abaqus correlated well with experimental findings, validating stress–strain responses and failure trends. The combined insights demonstrate the critical role of process parameters in tailoring the mechanical properties of FDM-printed PLA parts. https://ajme.aut.ac.ir/article_5869.html Solar air heaters offer a low-cost way to convert solar energy into usable heat, but their efficiency is limited by the inherently low heat transfer coefficient of air. To address this limitation, artificial roughness elements such as V-shaped ribs are commonly added to the absorber plate to boost turbulent mixing and improve thermal performance. This study numerically investigates the thermo-hydraulic characteristics of a solar air heater duct equipped with V-shaped ribs by analyzing the combined effects of angle of attack and relative rib width using computational fluid dynamics. The results demonstrate that both thermal performance and flow characteristics are influenced by rib geometry. The Nusselt number reaches its maximum enhancement of 2.8 times that of a smooth duct when using a single V-rib with a relative width of 1 and a 30° angle of attack. However, reducing the relative width results in progressively diminished heat transfer effectiveness. The thermo-hydraulic performance parameter peaks at 1.63 for the optimal relative width of 1 at a 30° angle of attack, indicating the most favorable ratio of Nusselt number enhancement to friction factor increase. These results offer essential guidance for optimizing roughened solar air heater designs, suggesting that a single, properly oriented V-rib offers the most favorable compromise between thermal enhancement and energy efficiency. https://ajme.aut.ac.ir/article_5941.html This research investigates the effective input parameters of the Elliptical Cross-Section Spiral Equal-Channel Angular Extrusion (ECSEE) method and selects the optimal performance. The influential parameters in the ECSEE method are considered as input factors in the experimental design, which are expressed in three parameters: punch speed, sample annealing, and the number of extrusion passes. Subsequently, a Taguchi design of experiments (DOE) table was created for each input parameter according to its variation range. After designing the experiments, the output results of forming force and plastic strain for each level were obtained using experimental tests. The optimization of the input values was investigated based on the S/N ratio criterion ("the smaller the better" for forming force and "the larger the better" for plastic strain). The obtained results indicated that the optimal test level in the ECSEE method for achieving the minimum forming force is using a punch speed of 6 or 9 mm/min, sample annealing at 300°C for 120 minutes, and 2 extrusion passes. Furthermore, to achieve the maximum plastic strain, the optimal parameters are a punch speed of 9 mm/min, sample annealing at 200°C for 120 minutes, and 6 extrusion passes. https://ajme.aut.ac.ir/article_5874.html This paper provides a hybrid control strategy for the aim of nullifying the vibration of flexible appendages in satellite structures. These vibrations often occur during the deployment of satellite panels. To maintain performance and ensure attitude stability, a robust control framework is essential. To achieve this, piezoelectric actuators are incorporated into the panels to actively suppress structural vibrations. Lyapunov Nonlinear Model Predictive Control (LNMPC) is introduced in order to guarantee satellite stability and robustness. This algorithm is similar to the Piece-Wise Affine (PWA) method, but the nonlinear dynamics of the system is used instead of linearization. Additionally, Anti-Unwinding Sliding Mode Control is employed into this algorithm and combined with LNMPC to neutralize the vibration actively, furthermore this composite controller assists to control both kinematics and dynamics properly also steering the reaction wheels to zero after every maneuver to save energy in the presence of uncertainty, external disturbance and actuators dynamics considered into the algorithm. Furthermore, close loop stability analysis is provided by utilizing a candidate Lyapunov function. https://ajme.aut.ac.ir/article_5974.html This research aims to enhance the hardening behavior of a non-rotating 2D tri-axial braided composite (2DTBC) fan blade, through investigating the backbone curve characteristics. This enhancement raises the blade’s natural frequencies at large oscillation amplitudes, thereby delaying the onset of resonance. A combination of different methods has been employed, including an Artificial Neural Network (ANN), an analytical method, the finite element method (FEM), and a single-objective genetic algorithm (GA). The ANN was used to establish the relationship between the braiding machine parameters and the structural characteristics of the braided fabric. Micromechanical modeling was utilized to determine the mechanical properties of the braided composite. Based on the first-order shear deformation theory (FSDT), the nonlinear free vibration partial differential equations of the composite blade shell were derived using Hamilton's principle. The FEM was employed to solve the differential equations and obtain the corresponding backbone curves. Finally, a single-objective genetic algorithm was deployed to optimize the braided composite structure in order to increase the hardening behavior of the blade. The obtained results demonstrate the viability of the proposed approach. The results indicate that the hardening behavior has increased by a factor of 6.8 compared to the non-optimized case. https://ajme.aut.ac.ir/article_5892.html Athletes’ balance control ability is essential in different sports. Effective analysis of athletes' balance control ability is an effective way for coaches and sports teams to identify subjects' skills. In the last few years, with the rapid growth of technology in sports, the necessity of using intelligent methods has increased. This study compares different artificial intelligence approaches to evaluate balance control ability by processing time-series data from the center of pressure. A recording pad collects center of pressure data from four types of subjects, ranging from professional skiers to non-athletes. Several experimental feature-extraction techniques were applied to the data, and the resulting features were used as input for artificial intelligence methods. This paper utilizes a multi-layer perceptron to classify subjects’ skill levels. Compared with other methods, the multi-layer perceptron achieves more than 92% accuracy in classifying subjects' proficiency, yielding the best performance. Other methods, including k-nearest neighbors and support vector machines, achieved 72% and 69% accuracy, respectively. Analysis of center of pressure data can help identify promising individuals for real-world applications. https://ajme.aut.ac.ir/article_5979.html Conformal cooling channels have been proposed as a promising alternative to traditional cooling channels. The objective of this paper is to introduce a novel method of producing milled groove conformal cooling channels (MGCCC) for injection molding using hard tooling. An experimental investigation was carried out by comparing the conventional cooling channel approach with CCC to optimize the cooling time. The study focuses on a specific case study of an "enclosure part" from a medium-scale industry(Mold Craft Engineers Pvt. Ltd. in Pune). The injection mold tools for this part used straight drilled cooling channels, which resulted in uneven cooling and longer cooling times. The milled groove CCC was designed to improve the cooling time and reduce cycle time, to conform to the shape of the cavity. The fabrication of the mold with CCC was performed using CNC machining. Milled grooves were sealed with a fitted plate and O-rings to prevent leakage. Temperature measurements were recorded using RTDs embedded near the cavity surface under controlled molding conditions. The experimental analysis, which involved temperature measurement of the molded part during the injection molding process, revealed that the mold with milled groove CCC exhibited shorter cooling times than the mold with straight cooling channels. Cooling time was reduced by 73.33% compared to the conventional cooling system. https://ajme.aut.ac.ir/article_5930.html Due to their suitable properties, iron aluminides have found numerous applications in various industries such as in the production of gas turbines, automotive combustion systems, corrosion-resistant coatings, heat exchanges, electrical and magnetic devices, and energy storage technologies. The aim of this research is to investigate the effect of copper content on the phase formation path and microstructure of products resulting from reactions that can be carried out in the Fe-Al-Cu powder system. For this purpose, samples with different copper contents (0, 0.2, 0.32 and 0.4 atom percent) and equimolar Fe and Al were prepared from elemental powders. The powders were compressed into disk shapes after mixing. Then, they were sintered at 950°C for 24 hours. The type of phases produced was determined using X-ray diffraction (XRD) analysis and the microstructure of the samples was determined using a scanning electron microscope (SEM) equipped with (EDX). The results showed that the type of phases produced changed depending on the amount of copper. The sample without copper only led to the formation of the FeAl phase. The addition of 0.2% copper also resulted in the formation of the CuAl₂ phase alongside the iron aluminide. Further increase to 0.32% copper led to the formation of the ω phase and at 0.4% copper, the I phase. Also, the amount of copper affected the amount of porosity produced in the samples. https://ajme.aut.ac.ir/article_5993.html This research investigates the nonlinear free oscillation analysis of imperfect, functionally graded, porous, stiffened, open conical panels resting on an elastic foundation under thermal conditions. To establish the governing nonlinear dynamic equations, the classical shell theory, the nonlinear von Kármán assumptions, and Hamilton’s principle are employed. Due to the use of the multiple scales method (MSM), the equations of motion must be rewritten in dimensionless form; therefore, the dimensionless parameters are introduced. The Galerkin approach is utilized to discretize the dimensionless partial differential equations (PDEs). By neglecting in-plane inertias and solving the resulting algebraic relations, the discretized system reduces to a nonlinear ordinary differential equation. Based on this final nonlinear ODE, the linear frequencies are extracted, and the numerical results are validated with previous studies for different geometries. Furthermore, the MSM is employed to determine the nonlinear frequency relationship. Finally, the effects of geometrical variations, material properties, imperfections, and foundation effects are investigated. The reported outcomes highlight the importance of imperfect FG-porous stiffened conical panels to multiple parameters, providing valuable insights into their vibration behavior under simply supported conditions.