Amirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Vibration Analysis of Open Spherical Sandwich Panels with Soft Core Rested on an Elastic Foundation Subjected to Various Impulse Loads603210.22060/ajme.2026.24389.6200ENSamanSadripourSchool of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, IranRaed HadiAl SaffahSchool of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, IranRamazan-AliJafari-TalookolaeiSchool of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, Iran0000-0003-4357-2597RezaAzadiSchool of Mechanical Engineering, Babol Noshirvani University of Technology, Babol, IranJournal Article20250723The study explores the behaviour of systems under both free and forced vibrations of spherical sandwich panels supported by an elastic foundation exposed to various impact load profiles. The panels consist of multilayer composite face sheets formulated based on the first-order shear deformation theory, and a soft core characterized by a higher-order theory employing third-order in-plane and second-order transverse displacement fields. By calculating the mechanical energy components, and introducing a higher-order element with nine nodes and 15 degrees of freedom for each node, the element stiffness and mass matrices were determined. Boundary conditions are simulated through distributed virtual springs. A free vibration problem is evaluated to extract the structure’s natural frequencies and mode shapes. Using the Newmark method, time response of displacement, velocity, acceleration, and phase planes are calculated for various impact profiles, specifically for half-sine pulses. This comprehensive analysis of sandwich panels' dynamic response under various impact loads reveals that the load profile critically determines structural behavior, essentially governing the boundary between safe operation and potential failure. For example, sudden loads like rectangular pulse emerged as the most critical case, causing extreme discontinuous responses across all dynamic parameters, and gradual loads (Gaussian/exponential) proved optimal for sensitive applications by generating smooth, controlled structural responses and providing ideal performance for stability-critical systems.https://ajme.aut.ac.ir/article_6032_fb3a30a2e3e8abdcbf63f0aaaadb06e4.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Analysis and Review of the Impact of Iran's Climatic Conditions on the Design of Nearly Zero Energy Buildings According to the Köppen-Geiger Method603610.22060/ajme.2026.24508.6209ENVahidRezaeeDepartment of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, IranMojtabaMasoumnezhadDepartment of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, Iran0000-0002-3395-8886Journal Article20250802This article proposes architectural strategies and comfort conditions for designing nearly zero-energy buildings (NZEBs) across different climatic regions of Iran, based on the Köppen-Geiger classification method and passive design techniques. According to the Köppen-Geiger climate classification, Iran's climate is divided into nine zones. The primary climatic zones considered in this study include Bwh, Bwk, Bsk, Bsh, Csa, Cfa, Csb, Dsa, and Dsb. The impact of climatic conditions on the design of nearly zero-energy buildings was analyzed using the Köppen-Geiger method. the selected cities within the mentioned climate zones were analyzed by the Climate Consultant software (CCS) in EPW format, utilizing the ASHRAE Standard 55 and also PMV (Predicted Mean Vote) comfort model. By inputting weather data from selected cities into CCS, output results including comfort conditions, natural ventilation, cooling, heating, and other parameters across the nine climatic zones were obtained. Additionally, during designing NZEBs, passive architectural parameters such as window shading, passive solar radiation, and internal heat generation in these nine climate zones were examined. The results showed that the BWh climate (Yazd) provides the highest thermal comfort at 19.7%, while the CFa climate (Anzali) provides the lowest thermal comfort at 3.6%. In the BWh climate, window shading, evaporative cooling, and internal heat gain have better conditions for comfort compared to other climates, with percentages of 16.8%, 25.8%, and 22.5%, respectively.https://ajme.aut.ac.ir/article_6036_567b8f5f423af15818a068235807edc0.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Aerodynamic Noise Sources Reduction of a Sedan Car via Surface Modifications using Wind Tunnel Experiments604610.22060/ajme.2026.25171.6254ENSadeghDavoodiDANA Research Laboratory, Department of Aerospace Engineering, Amirkabir University of Technology, Tehran, IranMostafaKazemiDepartment of Aerospace Engineering, Amirkabir University of Technology, Tehran, IranAkbarMahdavi ValaHead of CFD Department, Research and Development Center, Irankhodro Industrial Group, Tehran, IranMahmoudManiDepartment of Aerospace Engineering, Amirkabir University of Technology, Tehran, IranJournal Article20251124This research aims to investigate the external aerodynamics of the IKCO-DENA+ car, which leads to the annoying sound inside the cabin. In this research, the sources of aerodynamic noises were identified using wind tunnel tests on a 2/5 scaled model. Smoke flow visualization of the flow around the car for finding out aerodynamic characteristics and noise sources has been conducted. The results obtained from visualization showed that six different factors can be considered as a source of noises, including 1.the distance between the side mirror and the body, 2. the aerodynamic form of the side mirror, 3. the rear passenger quarter window, 4. the shark antenna, 5. car handles, and 6. indentation design feature on the rear door of the car. Then, within the next steps, the surface modification solutions regarding the identified noise sources were tested. In addition, Measurements using hot wire anemometry and pressure sensors were performed at different velocities of 18, 36, 54, 72, 90, 108 and 118.8 km/h. The results showed that surface modification related to quarter window led to a reduction of the flow disturbances and the aeronoise level on the car’s rear door glass significantly. Furthermore, modifying the side mirror of the car has considerably improved the aerodynamic behavior within the area of the front door glass. Consequently, these two modifications reduced pressure disturbances by 9% and 5%, respectively.https://ajme.aut.ac.ir/article_6046_73a427badebe0e32caa2e1fc7530b7f3.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Experimental investigation of CRDi diesel engine performance using neem biodiesel with a mixture of Al2O3 and ZnO nano fuel additives604810.22060/ajme.2026.24666.6219ENAshishkumar J.ModiDepartment of Mechanical Engineering, Government Engineering College, Bharuch – 392001, India0000-0002-2492-4967Vipul R.PatelDepartment of Mechanical Engineering, Government Engineering College, Bharuch – 392001, India0009-0006-3164-4193Bhupendra SPatilDepartment of Mechanical Engineering, Government Engineering College, Bharuch – 392001, India0009-0007-6687-7453Asfakahemad AShekhDepartment of Mechanical Engineering, Government Engineering College, Bharuch – 392001, India0009-0004-8423-2200Journal Article20250902For many years, biodiesel has been seen as an alternative fuel with the ability to eventually replace diesel. Products that are emitted when engines undergo a complete combustion reaction provide no direct health risks to humans. Due to certain fuel characteristics, biodiesel performs poorer during combustion process than diesel fuel. As a result, smoke emissions, complete combustion products like CO2, and incomplete combustion products including HCs, CO, and NOX are released into surrounding. An attempt has been made to enhance combustion and emission performance of CRDi-VCR type diesel engine using B20 neem biodiesel with a novel nanoparticle mixture of Al2O3 and ZnO as nano fuel additives for various dosing levels. B20 Neem biodiesel with nano additives was tested on a CRDi-VCR type diesel engine at a constant speed of 1500 rpm at various loads. Due to higher oxidation rate of hydrocarbon molecules, the nano additive reduced CO emissions in studies while improving the thermal conductivity, mass dissipation, and heat transfer of the tested nano fuels. Due to the improvement in the combustion reaction, CO2 emission increased with product of complete combustion. Brake specific fuel consumption was reduced at full load condition with the addition of 25 ppm NPs. Also, neem biodiesel fuel results in appreciably improved brake thermal efficiency, lower values of smoke opacity, and lower CO, NOX and HC emissions.https://ajme.aut.ac.ir/article_6048_6646b06b90bd13dabc11ddba01270d23.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Thermal-Dependent 2-D Magneto-Micropolar Fluid Flow over Stretching Surfaces in Porous Media: OHAM-Based Analysis with Viscous Dissipation and Radiation Effects605510.22060/ajme.2026.24746.6228ENHussainBashaDepartment of Mathematics, Government First Grade College, Zalaki-586204, Vijayapur, Karnataka, India0000-0003-4470-2074V.RamanjiniDepartment of Mathematics, Government First Grade College, Lingasuguru, Raichur –584 122, Karnataka, IndiaJournal Article20250915In this study, the convective transport of a temperature-dependent magneto-micropolar fluid over a stretching surface embedded in a porous medium is examined. The formulation accounts for viscous dissipation, internal heat generation or absorption, and radiative heat transfer modeled through the Rosseland diffusion approximation, which is appropriate for optically thick media. The governing equations, developed without the use of similarity transformations, are solved using the Optimal Homotopy Analysis Method (OHAM). The resulting velocity, microrotation, and temperature fields are illustrated through graphical and tabulated data across a broad range of physical parameters. Validation against existing literature demonstrates the reliability of the present approach. Quantitative analysis shows that the microrotation boundary layer decreases by approximately 18–25% with increasing micropolar parameter, while thermal boundary layer thickness increases by about 10–14% under stronger radiative effects. Moreover, micropolar fluids exhibit a thinner momentum boundary layer compared to Newtonian fluids under identical conditions. Specifically, the Newtonian case yields a thinner layer relative to the micropolar case . Overall, the results provide valuable insights into micropolar fluid behavior with practical implications in porous and radiative flow systems.https://ajme.aut.ac.ir/article_6055_5cd7edbe7a1a668fdc63c138002cc43a.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Experimental and Numerical Modal Analysis of Complete and Partial Bonding States of Single-Lap Adhesive Joints606610.22060/ajme.2026.24561.6212ENSetarehGarazhianDepartment of Mechanical Engineering, University of Tabriz, Tabriz, IranMiladShabani YousefabadDepartment of Mechanical Engineering, University of Tabriz, Tabriz, IranMorteza HomayounSadeghiDepartment of Mechanical Engineering, University of Tabriz, Tabriz, IranMir MohammadEttefaghDepartment of Mechanical Engineering, University of Tabriz, Tabriz, IranHasanBiglariDepartment of Mechanical Engineering, University of Tabriz, Tabriz, IranKarimShelesh-NezhadDepartment of Mechanical Engineering, University of Tabriz, Tabriz, IranJournal Article20250815This study evaluates the sensitivity of modal parameters to incomplete adhesion in single-lap adhesive joints by comparing the vibrational behavior of fully bonded joints and joints with a macroscopic partial bond (≈50% loss of bonded area in the overlap). Beyond prior studies on crack-like or delamination-type defects, often using intrusive or destructive inspections, the present work targets a practically relevant macroscopic manufacturing flaw within a fully non-destructive modal testing framework. An integrated experimental–numerical approach is employed: aluminum 7075-T6 beams bonded with epoxy 828 are tested using impact-hammer excitation and laser Doppler vibrometer, and responses are processed in MATLAB and MEscope to extract natural frequencies and damping ratios. A three-dimensional finite element model in Abaqus/CAE is refined via limited experimental calibration. Results show 3–15% reductions in the first eight bending natural frequencies of defective joints relative to intact ones, with stronger effects in higher modes due to dominant stiffness loss over minor mass reduction. The damping ratio increases about sevenfold (0.0032 to 0.0236) in the defective specimen, attributed to frictional dissipation at the unbonded interface and contact nonlinearities supported by mode-shape analysis. These quantified shifts in frequency and damping establish modal parameters as reliable, non-destructive indicators of incomplete adhesion in single-lap joints and provide a basis for vibration-based structural health monitoring and defect detection in adhesively bonded components in aerospace, automotive, and multi-material structures.https://ajme.aut.ac.ir/article_6066_2be5f9c2e3620eb73c2972d7552b6cb5.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Effect of Aluminum Oxide Nanoparticles on the Mechanical Properties of Natural Rubber/Styrene–Butadiene Rubber Blends Reinforced with Carbon Black and Titanium Dioxide Nanoparticles615610.22060/ajme.2026.24943.6236ENZaid Ghalib AbdulkadhimAl-JlaihawiDepartment of Mechanical Engineering, Faculty of Engineering, University of Kufa, Najaf, IraqSuadad NooriGhaniDepartment of Mechanical Engineering, Faculty of Engineering, University of Kufa, Najaf, IraqMuna HameedAlturaihiDepartment of Mechanical Engineering, Faculty of Engineering, University of Kufa, Najaf, IraqJournal Article20251020This study investigated the reinforcing effect of aluminum oxide and titanium dioxide nanoparticles, used individually and as hybrid fillers, on the mechanical performance of natural rubber/styrene–butadiene rubber vulcanizates reinforced with carbon black. The composites were fabricated by conventional compounding and compression molding following ASTM standards. Mechanical performance was evaluated through tensile strength, compression set, hardness, and scanning electron microscopy. A total of 100 specimens were prepared and classified into two groups according to nanoparticle loading. The results demonstrated that hybrid incorporation of aluminum oxide and titanium dioxide nanoparticles produced superior reinforcement compared with the use of titanium dioxide alone. The optimum formulation, containing 10 parts per hundred rubber of aluminum oxide and 8 parts per hundred rubber of titanium dioxide, achieved the highest tensile strength of 27.93 ± 0.71 MPa and the maximum hardness of 72 ± 5 International Rubber Hardness Degrees. The lowest compression set (19.65 ± 1.60%) was obtained with titanium dioxide alone, whereas the hybrid system maintained a low compression set (24.66 ± 1.30%) while simultaneously providing substantial improvements in tensile strength and hardness. Scanning electron microscopy revealed a uniform nanoparticle distribution with limited agglomeration and good interfacial adhesion, explaining the enhanced mechanical behavior. These findings demonstrate that hybrid aluminum oxide–titanium dioxide nanoparticles are effective reinforcing fillers for high-performance rubber composites.https://ajme.aut.ac.ir/article_6156_2eacc82231f2e62f9acb38bece54635e.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-293710420261001Additive Manufacturing of Biopolymers and Biocomposites: Recent Advances, Challenges, and Biomedical Applications604510.22060/ajme.2026.24691.6223ENToniOkviyantoDepartment of Mechanical Engineering, Politeknik Negeri Sriwijaya, Palembang, Indonesia0009-0009-8676-7205HendradinataHendradinataDepartment of Mechanical Engineering, Politeknik Negeri Sriwijaya, Palembang, IndonesiaTaufikurrahmanTaufikurrahmanDepartment of Mechanical Engineering, Politeknik Negeri Sriwijaya, Palembang, IndonesiaAlmadora AnwarSaniDepartment of Mechanical Engineering, Politeknik Negeri Sriwijaya, Palembang, IndonesiaEllaSundariDepartment of Mechanical Engineering, Politeknik Negeri Sriwijaya, Palembang, IndonesiaIndraGunawanDepartment of Mechanical Engineering, Politeknik Negeri Sriwijaya, Palembang, IndonesiaJournal Article20250906Additive manufacturing of biopolymer composites is rapidly advancing biomedical engineering. By combining synthetic polymers with natural biopolymers, inorganic ceramics, nanomaterials, and bioactive molecules, AM enables patient-specific constructs with high geometric precision and tunable biological performance. These materials support applications across hard and soft tissues, including bone regeneration, cartilage repair, wound healing, vascular grafts, and cancer modeling. Despite this progress, major barriers remain: mechanical-degradation mismatches, limited vascularization in thick constructs, photoinitiator-related cytotoxicity, and inter-laboratory variability that reduces reproducibility and slows clinical translation in real-world settings. Broader adoption is further constrained by the lack of standardized protocols and clear regulatory pathways. We compare AM modalities (extrusion, vat photopolymerization, and powder-bed processes) through a cost-benefit lens, outlining when each optimally balances resolution, throughput, sterility, and cell compatibility. To address these gaps, recent work (2020–2025) is shifting the field from static scaffolds toward adaptive, intelligent, and sustainable platforms, leveraging 4D printing, nanotechnology-enabled reinforcement and bioactivity, AI-driven design optimization, and greener feedstocks such as sustainable biopolymers. Notably, 2025 reports on multi-material bioprinting for neural tissues show improved print fidelity and bioactivity, enabling more realistic microvascular networks and neural interfaces. By synthesizing these advances and critically evaluating current limitations, this review proposes strategic directions for AM to mature into a clinically relevant, globally sustainable manufacturing approach. Biopolymer composites are not incremental upgrades; they are pivotal enablers of next-generation regenerative medicine.https://ajme.aut.ac.ir/article_6045_f449d27f42a9b2a25b247ac15989090f.pdf