https://maj.ihu.ac.ir/ Aerospace Mechanics en daily 1 Fri, 22 May 2026 00:00:00 +0330 Fri, 22 May 2026 00:00:00 +0330 https://maj.ihu.ac.ir/article_210734.html Vibration energy harvesting is one of the methods that is used as energy supply for electronic devices that have low power consumption (such as sensors). With the advent of piezoelectrics and due to the properties of piezoelectric materials, they were quickly introduced as one of the most common materials for energy harvesting. Currently, vibration energy harvesting with piezoelectric material can produce more than 300 microwatts per square centimeter of power. Piezopolymers are one of the types of piezoelectric materials. In this work, with the help of EAPap piezopolymer materials, which are a thin film of cellulose, energy-harvesting beams have been made. By changing the location of the piezoelectric along the length of the cantilever beam, the changes in voltage, current and output power have been investigated. It can be seen that by changing the position of the piezoelectric on the beam and getting closer to the end of the beam, the output power, current and voltage have also increased due to the increase in the amount of strain. https://maj.ihu.ac.ir/article_210736.html In the present study, the increase in the accuracy of numerical simulation of two-phase combustion in the combustion chamber of a ducted rocket engine has been investigated. The present problem includes two fuel flows with gas and solid phases. For the numerical simulation of two-phase combustion in a ducted rocket engine, ANSYS Fluent software has been used. For the modeling of turbulence, the two-equation model of k-ε RNG has been intended. Also, for the modeling of combustion and solid carbon particles, the non-premixed combustion model and the DPM model have been used, respectively. Using an unorganized grid cell, examining the sensitivity of the numerical solution results to the number of grid cells, the value of the flammability limit of the solid fuel flow, and using the turbulent dispersion model and its sub-parts in discrete phase modeling are the applied differences in the present CFD research. In fact, the use of the turbulent dispersion model and its sub-parts has had a major impact on improving the numerical simulations performed. The difference between the two-phase combustion efficiencies obtained from CFD in the present work and the two-phase combustion efficiencies obtained from the experimental work in configurations 1, 2, 3, 4, and 5 has decreased by 22%, 6%, 0.4%, 4% and 5%, respectively, which means an increase in the accuracy of the numerical simulation of two-phase combustion in the present work. https://maj.ihu.ac.ir/article_210978.html In this paper, the sizing method and reference battery state of charge (SOC) trajectory for a hybrid aircraft under failure conditions are presented. With this aim, first, the types of hybrid-electric propulsion system (HEPS) structures along with their components are introduced. Then, the failure modes of HEPS main components and their impact on the aircraft performance are investigated. Next, the sizing of parallel HEPS under all-turbine and battery pack failures is formulated. Then, the reference SOC trajectory is presented by simulating the HEPS during a real flight mission, to ensure the safe landing of the aircraft in the event of all-turbine failure. So that the battery SOC in the cruise and descent phases should be about 35-45% and 65%, respectively. Finally, using the results of the parallel hybrid aircraft simulation under emergency failure modes, the correctness of the proposed sizing procedure has been proven. In addition, by presenting the simulation results of the healthy hybrid aircraft, the satisfaction of the performance constraints of the parallel HEPS has been validated. https://maj.ihu.ac.ir/article_210669.html In this paper, dynamic analysis of a composite wing of a typical airplane with Piezoelectric sensor and actuator patches has been performed using ABAQUS finite element package. The modal analysis for a 3-D model of a specified wing made up of three different composite material including basalt-epoxy, kevlar-epoxy and carbon epoxy has been done to determine and compare modal shapes of the composite wing and its corresponding natural frequencies. Then, based on structural analysis, 3-D distributions of stress, strains and displacements components are obtained. Moreover, using a written code in MATLAB/Simulink applying the PID controller to the model, the vibration control of the composite wing has been investigated. To do this, the responses of both open and closed loop control models of the system with PID controller under external disturbance forces in the form of unit step, ramped and sinousuidal input functions are extracted. It was shown from the obtained results that the composite wing made up of carbon-epoxy material has modal natural frequencies higher than that of aluminum wing. Also, considering the closed loop PID controller for the composite wing with Piezoelectric actuators revealed that a very good performance of the system against applied disturbances in which the active PID controller reduced the wing tip displacement under disturbances in the form of unit step, ramped and sinousuidal functions by 96.5%, 98% and 99%, respectively. https://maj.ihu.ac.ir/article_210979.html Composite lattice shells are widely employed across various industries due to their exceptional strength-to-weight ratio and ability to sustain significant loads while remaining lightweight. Buckling analysis and the accurate prediction of the critical buckling load are among the most essential design considerations for these structures. In this study, the influence of incorporating carbon nanoparticles (1, 1.5, 3, 4, and 5 wt%) on the elastic properties of the resin was investigated using the Modified Halpin–Tsai model. The effective properties of the composite material in the conical lattice structure were then estimated through the rule of mixtures. Based on these properties, finite element models were developed in Abaqus to predict the buckling load, and the numerical results were validated against experimental data. Furthermore, to enable neural network–based prediction of the critical buckling load, 75 parametric models were generated in Abaqus with varying nanoparticle concentrations and aspect ratios (0.5, 1, and 1.5) for the cross-sections of helical and circumferential ribs. The corresponding critical buckling loads were calculated and used to train neural networks. Networks with different neuron counts and training epochs were systematically evaluated, and the optimal architecture for accurate prediction of the critical buckling load was identified. https://maj.ihu.ac.ir/article_210735.html In this study, the aerodynamic behavior of a moderately cambered NACA 4412 airfoil was investigated over a wide range of angles of attack and Reynolds numbers. Computational fluid dynamics (CFD) simulations were performed using ANSYS Fluent with the Spalart–Allmaras turbulence model. The mesh was designed to be uniform with high refinement in critical regions, including the leading edge and the flow separation area. Validation of the CFD results against experimental wind tunnel data showed that the lift and drag coefficients were accurately predicted both before and after stall. Flow field analysis revealed that stall occurrence was caused by early boundary layer separation in the suction region and the formation of a large recirculation zone behind the leading edge, resulting in a sudden drop in lift coefficient and a sharp increase in drag coefficient. Increasing the Reynolds number delayed stall onset and increased the maximum lift. To enable rapid prediction of aerodynamic coefficients, a multilayer neural network was developed with angle of attack and Reynolds number as inputs, and lift and drag coefficients as outputs. The proposed model was able to predict the stall angle with over 90% accuracy. These results demonstrate that the combination of CFD and neural networks provides an efficient and cost-effective approach for predicting airfoil aerodynamic behavior, and can be applied in airfoil optimization, blade performance enhancement, and the development of active stall control systems. https://maj.ihu.ac.ir/article_210980.html Seamless API 5L X52 steel pipes are widely used in oil and gas transmission systems, but under harsh operating conditions including corrosive and abrasive environments, they have relatively limited corrosion and wear resistance, which can lead to reduced service life and increased maintenance costs. In this study, with an industrial-oriented approach and with the aim of simultaneously improving mechanical properties and corrosion behavior, a coating of nickel-based alloy Inconel 625 was applied to the surface of API 5L X52 steel pipes by metal cladding method. As a common industrial welding process, this method has the practical implementation capability on an industrial scale. After the coating operation, the chemical composition of the coating was determined by emission spectrometry and the mechanical properties including hardness, tensile, bending and impact were evaluated at a temperature of -30 ℃. Also, the corrosion behavior was investigated by performing pitting corrosion tests and susceptibility to intergranular corrosion by immersing the samples in a boiling solution containing 25 g of ferric sulfate and 236 ml of sulfuric acid for 120 hours. The results showed that the Inconel 625 coating had a stable and uniform chemical composition at different surface and thicknesses and resulted in a 51% increase in the hardness of the steel substrate. Also, the corrosion rates were 0.000193 g/cm² and 1.278 (mm/year) in the pitting and intergranular corrosion tests, respectively, indicating a significant improvement in corrosion resistance along with an increase in mechanical properties of API 5L X52 steel after applying the Inconel 625 coating.