Sharif University of TechnologyScientia Iranica1026-3098311320240801Minimum stiffness and optimal position of intermediate elastic support to maximize the fundamental frequency of a vibrating Timoshenko beam9679792323410.24200/sci.2023.59366.6196ENH.EbrahimiDepartment of Mechanical Engineering, Takestan Branch, Islamic Azad University, Takestan, IranF.KakavandDepartment of Mechanical Engineering, Takestan Branch, Islamic Azad University, Takestan, IranH.SeidiDepartment of Mechanical Engineering, Takestan Branch, Islamic Azad University, Takestan, IranJournal Article20211108The optimal position and minimum support stiffness of a vibrating Timoshenko beam are investigated to maximize the fundamental frequency. The Finite element method is employed. The intermediate support's ideal position and minimal stiffness for a wide variety of slenderness proportions were achieved after validating the finite element model with the Euler-Bernoulli and Timoshenko model's analytical solution. It was observed that the ideal position of intermediate support and its minimum stiffness are sensitive to the slenderness ratio. According to the maximum-minimum theorem of Courant, the optimum position is at the zero of the second mode shape function (ZSMS). Also, it was observed that for thick cantilever beams with intermediate support at the optimal location, the minimum support stiffness is less than 266.9, which was reported in the literature for the Euler-Bernoulli beam. The minimum stiffness of familiar end conditions of an optimally located beam is presented for a wide range of slenderness ratios. Since, in many practical applications, it is impossible to locate support at the optimal position, the minimum support stiffness for a beam in which its intermediate support is not located at the optimal position is obtained for various boundary conditions and slenderness ratios.https://scientiairanica.sharif.edu/article_23234_9efd77e74e7249e5157916a1ab9c662d.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801Modeling and multi-objective optimization of low-frequency vibration-assisted chemical machining using central composite design in response surface methodology9809922322210.24200/sci.2023.59618.6339ENJ.RahmaniMechanical Engineering Faculty, Department of Engineering, University of Zanjan, Zanjan, IranM. M.MohammadiMechanical Engineering Faculty, Department of Engineering, University of Zanjan, Zanjan, IranR.Khamedi- Mechanical Engineering Faculty, Department of Engineering, University of Zanjan, Zanjan, Iran
- Department of Mechanical Engineering, School of Engineering and Applied Science, Khazar University, Baku, AzerbaijanJournal Article20211225Increasing the etching rate is one of the main optimization targets in the chemical machining (CM). Traditionally, this target is fulfilled by some costly techniques like selecting stronger etchants and increasing the etchant concentration. Also, other methods like increasing the etchant temperature and stirring the etchants by agitators are employed for increasing the etching rate. One of the advantages of these methods is reduction of the consumption of acidic etchants which results in the cost reduction and making an eco-friendley process. In this article, a systematic experimental study is performed on vibration-assisted CM of copper. In this technique, the workpiece vibrates in the etchant during the CM. For evaluating the performance of machining, effects of amplitude and frequency of vibrations, along with the temperature and concentration of acidic etchant, on material removal rate, surface roughness and machining undercut are studied experimentally. The experiments are designed by Central Composite Design (CCD) in Response Surface Methodology (RSM). Also, multi-objective optimization is performed by defining a desirability function. The optimal vibro-assisted process parameters are temperature 60 ̊C, etchant concentration 600 g/l, vibration frequency 25 Hz, and vibration amplitude 1.5 mm, to get optimal outputs on the desired parameters.https://scientiairanica.sharif.edu/article_23222_48d1f82c9e5a9b404cc1f7f3c51023d4.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801Thermal Comfort and Energy Analysis in Ceramic Tile99310062323710.24200/sci.2023.60138.6747ENH. IbrahimKemaneciEczacibasi Building Products, Bozuyuk, Bilecik, TurkeyO. O.YolcanDepartment of Mechanical Engineering, Kutahya Dumlupunar University, Kutahya, TurkeyR.KoseDepartment of Mechanical Engineering, Kutahya Dumlupunar University, Kutahya, TurkeyJournal Article20220429In this study, the thermal touch comfort of ceramic tiles was investigated. For this purpose, energy analysis was made for the heat transfer during touch and the surface temperature during touch was calculated. It is explained how the thermal inertia phenomenon contributes to the calculation of the surface temperature. It has been revealed why ceramic tiles feel cold when touched. In order to examine the tactile comfort, the structure of the human skin and the mechanism of feeling the temperature are shown. In addition, for other coating materials at the same temperature as the ceramic tile, the surface temperatures during touch were calculated and compared. Previous studies to increase thermal comfort in ceramic tiles are discussed. It was calculated how much the thermal comfort increased as a result of coating the ceramic tile with a polymer material. The applicability of the coating option and how close it is to the goal of increasing thermal comfort are discussed. Thus, by calculating how much the coated ceramic tile improves the thermal comfort, a basic study has been put forward to evaluate the thermal comfort improvements to be made on many surfaces used as coating elements in buildings and touched by people.https://scientiairanica.sharif.edu/article_23237_c4bd0bd286c51eaa5cca5e8a87f19a1a.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801On the solutal and thermal Marangoni convection arising in the self-rewetting fluid flow under hydromagnetic consideration100710192326310.24200/sci.2023.60381.6774ENV. KumarChaurasiyaDepartment of Mathematics, National Institute of Technology, Jamshedpur-831014, Jharkhand, IndiaR.TripathiDepartment of Mathematics, National Institute of Technology, Jamshedpur-831014, Jharkhand, IndiaR.SinghDepartment of Mathematics, National Institute of Technology, Jamshedpur-831014, Jharkhand, IndiaJournal Article20220508In present research article, we address the magnetically controlled thermal and solutal Marangoni convection in the flow of self-rewetting power-law liquid over a disk, in the existence of space dependent heat source. The self re-wetting property of fluid is modelled by considering a quadratic dependence of surface tension on temperature and species concentration. The aforementioned problem is modelled by simplified Navier-Stokes equations. Identifying the appropriate transform variables is essential for developing ODEs (ordinary differential equations) from original PDEs (partial differential equations) that describe the flow conditions. The resulting ODEs are solved by using bvp4c routine of MATLAB and numerical solutions are presented via Graphs and tables, illustrating the impact of several factors on fluid velocity, temperature, concentration. Computation of the quantities of physical interest viz. Nusselt and Sherwood numbers are also done from those numerical solutions. One of the key finding of present research work is that the Marangoni convection works differently for pseudo--plastic fluid and dilatant fluid. On increasing thermal Marangoni convection the temperature of dilatant fluid reaches a peak value much closer to the disk than temperature of pseudo plastic fluid.https://scientiairanica.sharif.edu/article_23263_d52d78d77130d3d5c3e7baf0e3bb8cac.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801Improvement of Savonius wind turbine performance with using wind collector102010292322710.24200/sci.2023.60454.6809ENB.Deda AltanFaculty of Engineering, Department of Mechanical Engineering, Akdeniz University, Antalya, 07058, TurkeyA.GungorFaculty of Engineering, Department of Mechanical Engineering, Akdeniz University, Antalya, 07058, TurkeyJournal Article20220519In this study, the improvement of the turbine performance of Savonius, one of the vertical axis wind turbines, was carried out numerically. The numerical approach used in the improvement studies was supported by experimental results and was confirmed. Within the scope of this improvement, a wind collector was placed in the turbine front zone to decrease the negative moment on the counter-rotating blade of the Savonius turbine. To obtain the highest turbine performance, all of the changes in the design parameters of this wind collector, such as the wind inlet width, wind outlet width, collector length, and collector height, were examined, and ideal design parameters of the collector were specified. The geometric parameters of the investigated wind collector were taken depending on the circular dimension of the Savonius turbine used. Unsteady simulations for different geometric parameters using the sliding mesh approach were performed in the CFD program. According to the numerical analysis results, the power-coefficient of the conventional turbine was increased to 0.23 levels by using the wind collector with the ideal geometric parameters. Thus, with the use of a wind collector, the power coefficient of a conventional Savonius wind turbine was improved by about 54%.https://scientiairanica.sharif.edu/article_23227_d5390eba6dba313ba42cd47483f61b66.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801A novel method (a tube with successive increase and reduction in diameter) to increase nanofluid heat transfer in a tube103010422325310.24200/sci.2023.60676.6935ENAhmadBedramPh.D. Graduate of Sharif University of Technology (Supervisor: Prof Ali Moosavi),
Assistant Professor, Department of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, IranJournal Article20220628In this paper, a new geometry has been proposed to increase heat transfer in tubes. The fluid used was water-aluminum oxide (Al2O3) nanofluid. The results showed that the proposed geometry in this study (compared to a simple tube) in addition to increasing heat transfer, reduced the flow pressure drop, which is a great advantage over previous methods. Reynolds numbers of 2-300 and nanoparticle volume fraction of 0-3.5% have been investigated. Profile of temperature, velocity and pressure has been presented for different Reynolds numbers, nanofluid volume fractions and sections of geometry. In addition, variations of Nusselt number in different Reynolds numbers and volume fractions have been studied. For the Reynolds number 50, increasing the temperature of the fluid of the geometry proposed in this study was 52% higher than that of a simple tube under the same operating conditions. For the Reynolds number 50, the pressure drop of the geometry proposed in this study was 24% less than that of a simple tube under the same operating conditions. The results showed that the change in volume fraction of nanoparticles had a small effect on the Nusselt number. It was found that increasing the Reynolds number increased the Nusselt number.https://scientiairanica.sharif.edu/article_23253_17d658b862561231bb3e6509bfd19251.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801Cooling performance of turning M2 steel by using copper nano fluids104310552346110.24200/sci.2023.60857.7026ENK.GanesanDepartment of Mechanical Engineering, Jaya Engineering College, Chennai 602024, IndiaM.Naresh BabuDepartment of Mechanical Engineering, Easwari Engineering College, Ramapuram, Chennai 600089, IndiaP.GurusamyDepartment of Mechanical Engineering, Chennai Institute of Technology, Kundrathur, Chennai 600069, IndiaM.SanthanakumarDepartment of Mechanical Engineering, GRT Institute of Engineering and Technology, Tiruttani 631209, IndiaJournal Article20220728Minimum quantity Lubrication (MQL) is a technique used to reduce the utilization of cutting liquids in accomplishing a perfect and well-disposed condition. In this examination, the machinability of M2 steel which is hard-to-machine material utilized in key applications was researched under three separate cutting strategies such as dry environment, oil environment, and copper nanofluids with minimum quantity lubrication as environment. The turning tests were conducted utilizing carbide inserts on five separate cutting speed with constant feed and depth of cut. The maximum roughness value obtained with dry condition is 3.75 µm, for oil is 1.7 µm and nanofluid is 0.81 µm. The extreme flank wear values attained is 0.16 mm, 0.055 mm and 0.04 mm for dry, oil and nanofluid conditions. The reduced value of surface roughness (0.45 µm) and flank wear (0.04 mm) were obtained when the machining was performed under copper nanofluid as a coolant.https://scientiairanica.sharif.edu/article_23461_b1a54857c1424a383aaefa7e3fbe47d2.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801Effect of variable heat source and gravity variance on the convection in porous layer with temperature dependent viscosity105610622326410.24200/sci.2023.60864.7028ENY. H.GangadharaiahDepartment of Mathematics, RV Institute of Technology and Management, Bangalore-560076, IndiaN.ManjunathaDepartment of Mathematics, School of Applied Sciences, REVA University, Bangalore-560064, IndiaYellammaYellammaDepartment of Mathematics, School of Applied Sciences, REVA University, Bangalore-560064, IndiaF.Mebarek-OudinaDepartment of Physics, Faculty of Sciences, University of 20 Ao^ut 1955-Skikda, B.P. 26, 21000 Skikda, AlgeriaM.SankarFaculty of Mathematics, University of Technology and Applied Sciences, Ibri-516, Sultanate of OmanJournal Article20220729The joint influence of variable heat source pattern and temperature-reliant viscosity on the onset of convective motion in porous bed in the presence of gravity variance have been investigated. The linear analysis is performed using normal mode analysis and the Galerkin technique is applied to analyze the impact of variable heating and changeable gravity field on the behaviour of system stability. The exponential temperature dependent viscosity is considered. We examined three different types of heat source and gravity variance function combinations: Convection is accelerated by increases in viscosity and the gravity variance parameter, but decelerated by increases in the heat source strength. It has been shown that the configuration is more stable when the gravity variance and heat source functions are combined in instance (ii), but less stable when they are combined in case (iii).https://scientiairanica.sharif.edu/article_23264_ee194430f329e1fbe97cbe7b665ec2bd.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801Mechanical behavior and sliding wear assessment of Al2024/TiC metal matrix composite using Taguchi and spotted hyena optimization106310762351710.24200/sci.2024.57484.5261ENR.SureshDepartment of Mechanical and Manufacturing Engineering, MS Ramaiah University of Applied Sciences, Bangalore-560058,
IndiaA. G.JoshiDepartment of Mechanical Engineering, Canara Engineering College, Bantwal-574219, IndiaM.ManjaiahDepartment of Mechanical Engineering, National Institute of Technology, Warangal, 506004, IndiaS.KumarDepartment of Mechanical Engineering, Symbiosis Institute of Technology, Pune-412115, IndiaK. N.BharathDepartment of Mechanical Engineering, G.M. Institute of Technology, Davangere-577006, IndiaJournal Article20210106The microstructure, mechanical and tribological properties of titanium carbide particles reinforced Al2024 metal matrix composites (Al MMCs) were investigated. Fractography analysis of tensile test specimen revealed that debonding was prominent in 3% TiC reinforced Al MMCs, while clevage pattern failure was pronounced in 6% and 9% TiC reinforced MMCs. Tribological property was studied as sliding wear behaviour of MMCs. ANOVA analysis was employed to understand the effect of parameters, interaction effects was studied through response surface plots. Further, regression model was developed to correlate process parameters and wear. The worn surface analysis shown the formation of ridges and parallel furrows on surface in sliding direction. Al/TiC composites exhibited better mechanical properties and wear resistance compared to Al2024 alloy. The optimization of wear for its minimum value was achieved through spotted hyena optimization algorithm. The wear loss at optimized parameter was validated through experimental value and compared with Taguchi’s technique.https://scientiairanica.sharif.edu/article_23517_c3db19e6bb7e01dbfcbcf8a71bc91e61.pdfSharif University of TechnologyScientia Iranica1026-3098311320240801Investigation on flow characteristics of generic car body with different boundary conditions107710892329510.24200/sci.2023.59961.6523ENS.KeiyinciFaculty of Engineering, Cukurova University Automotive Engineering, Adana, 01380, TurkeyO.BasFaculty of Engineering, Amasya University, Mechanical Engineering, Amasya, 05000, Turkey0000-0003-2301-2306M.Atakan AkarFaculty of Engineering, Cukurova University Automotive Engineering, Adana, 01380, Turkey0000-0002-0192-0605Journal Article20220214In research automotive aerodynamics, it is not common to focus on a specific vehicle due to restricted access to the CAD geometries, their short life span, and limited validation data. For this reason, researchers prefer generic bodies that look like automobiles such as Ahmed Body in their investigations. However, the absence of moving ground and rotating wheels makes these generic bodies unrealistic for aerodynamic studies. In this context, including wheels in CFD simulations, varying ground and wheel boundary conditions, and comparing their qualitative and quantitative flow parameters with the original Ahmed Body experiment is the main objective of this paper. Results have shown that changing stationary ground and wheel boundaries into moving and rotating boundaries do have minor effects on wake characteristics and drag coefficients. However, just the presence of wheels on the model increases force coefficients significantly (increment in drag and lift coefficients by 27.32% and 188.5 counts, respectively.) even though these boundaries are stationary. As a result, the absence of moving ground and rotating wheels can be tolerated to some extent (especially for experimental studies in which inclusion of moving and rotating boundaries may have difficulties). However, a study cannot be evaluated exactly with a model without wheels.https://scientiairanica.sharif.edu/article_23295_b2b60f0727896eaf9584015df0b45ff7.pdf