Amirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Development of Theoretical Model to calculate Steam Hammer Force on Shock Absorber in Multi Series Pipeline315330478610.22060/ajme.2022.20897.6023ENHosseinNouriDepartment of Mechanical Engineering, Sanandaj Branch, Islamic Azad University, Sanandaj, Iran0000-0002-5247-1520Journal Article20211218This research work allocates to physical models in order to simulate real world results of the steam hammer at turbine multi-series pipeline in power plants. The aim of this study is to investigate the effect of a steam hammer on a steam turbine line and calculation the force on the shock absorber at the end of the main pipeline. For this purpose, the new theoretical model based on thermodynamic relationships and accurate calculation of wave speed propagation was developed and implemented into the physical model. The main achievement of this research is to present a simple and accurate theoretical model that can provide a bridge between hydro-mechanical data and estimates the impact force of the steam hammer on piping with less computational effort than finite element and a less costly setup than experimental models. The method of characteristics as a complement to the theoretical model was applied and compared. In this work, special attention is devoted to the study of the most relevant process parameters, with emphasis on their meaning, effects, and mutual interaction. The present paper organizes a theoretical model and numerical method of characteristics to predict steam hammer transients behavior in a multi-series pipeline. The initial results are promising and indicate the possibility of using the proposed simple yet, but efficient theoretical model than finite element models in terms of quality, cost, and time consumption of producing results.https://ajme.aut.ac.ir/article_4786_41346c0c2e0a44afe3acf3b9b08c0ec6.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Experimental Study on the Wear of Liner in Tumbling Mill under Dry and Wet Conditions331340481610.22060/ajme.2022.20778.6017ENMoslemMohammadi SoleymaniDepartment of Mechanical Engineering, Payame Noor University (PNU), Tehran, IranAliakbarMajidi JirandehiDepartment of Mechanical Engineering, Payame Noor University (PNU), Tehran, IranAlirezaArab SolgharDepartment of Mechanical Engineering, Vali-e-Asr University, Rafsanjan, IranJournal Article20211112Lifters/liners worn in tumbling mill and consequently their dimensions change during the course of operation. These changes in dimensions have a significant influence on the overall economic performance of the mills. In this project, the influences of slurry filling and slurry concentration on the wear of lifters were investigated using a pilot mill of 1m diameter and 0.5m length. Copper ore with a size smaller than one inch was used to prepare slurry at 40%, 50%, 60%, 70%, and 80% solids concentration of mass. The tests covered a range of slurry filling from 0.5 to 2.5 with ball filling at 20% and mill speeds at 75%. The mill grinding mechanism in this pilot mill is a combination of both impact and abrasion mechanisms. It was found that the lifters’ wear rises with the increase of feed filling in the mill under dry conditions. During the wet condition, when there is an increase in the slurry filling and slurry concentration, the wear decreases. In wet grinding, the relative velocity between the materials and the lifters is more than in the dry mode and the wear is 1.5–3 times greater than in the dry condition.https://ajme.aut.ac.ir/article_4816_2d54548653911cf427df89549aa87ff3.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Low Velocity Impact Response of Sandwich Beams with Composite Face-Sheets and Foam or Honeycomb Core: Analytical Modeling and Finite Element Simulation341362481710.22060/ajme.2022.20713.6014ENPooryaKarvanDepartment of Mechanical Engineering, Razi University, Kermanshah, IranSaeedFeliDepartment of Mechanical Engineering, Razi University, Kermanshah, IranJournal Article20211028In this paper, an analytical solution for the static indentation and low velocity impact response of composite sandwich beams with an orthotropic symmetric composite face-sheets and foam or honeycomb core is presented. The indentation force during impact loading consists of two regimes, one for small indentations of the top face-sheet due to bending moments and the other for larger deformation due to membrane forces. Also, the crushable core is considered a rigid-plastic foundation, and the elastic aspect is neglected. To obtain a more accurate approximation of the static indentation of the beam, both the local and global deformation of the sandwich beam are considered. The minimum potential energy method is applied for the extraction of governing equations. Furthermore, by developing a three dimensional finite element model through the ABAQUS code, the low velocity impact on composite sandwich beams with foam core is simulated. The contact force history, maximum contact force, and upper face-sheet displacement results computed by the analytical model are compared with experimental and ABAQUS simulations. A good agreement between the analytical model, finite element simulation, and experimental results, is observed. https://ajme.aut.ac.ir/article_4817_b3af9f129d8e78e9d3e320153f3315f5.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Design of Robust Proportional-(Proportional-Derivative) Controller for an Autonomous Underwater Vehicle Using Quantitative Feedback Theory in the Diving Plane363386482110.22060/ajme.2022.20964.6026ENFarhadSafariDepartment of Mechanical Engineering, Yazd University, Yazd, IranMansoorRafeeyanDepartment of Mechanical Engineering, Yazd University, Yazd, Iran0000-0002-1566-6687MohammadDaneshDepartment of Mechanical Engineering, Isfahan University of Technology, Isfahan, IranJournal Article20220108In this paper, a robust proportional-(proportional-derivative) controller is designed for an autonomous underwater vehicle using quantitative feedback theory in the presence of plant uncertainty and disturbances in diving plane motion. The controller is designed in cascade feedback in the presence of parametric uncertainty, ocean currents, sea waves, and fin error. The proportional-derivative controller controls the angle of the vehicle pitch and an outer proportional loop controller will control the vehicle depth. Since using classical methods to adjust proportional-derivative for the inner loop and proportional for the outer loop, despite the plant uncertainty and the presence of disturbances, is complex and time-consuming. therefore, the quantitative feedback theory technique, as a robust controller method, is used in this research. System stability is considered in the design process. All design steps are based on linearized equations of motion but the performance of the proportional-(proportional-derivative) controller designed by the robust quantitative feedback theory method is simulated numerically for nonlinear dynamic equations of motion. The simulation results show that the designed proportional-(proportional-derivative) controller using quantitative feedback theory offers robust stability, disturbance rejection, and proper reference tracking over a range of autonomous underwater vehicle parametric uncertainties.https://ajme.aut.ac.ir/article_4821_c82f037dcc2b9e54c9e8ed80df4858c1.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Polylactic Acid /High-Ratio Natural Kenaf Fiber Biocomposite Sheets Processed by Calendering Melt Mixing Technique387400471710.22060/ajme.2022.20621.6010ENMehdiKarevanDepartment of Mechanical Engineering, Isfahan University of Technology, Isfahan, Iran0000-0003-2584-4739Journal Article20211003Biodegradable polymers reinforced with cellulose-based natural fibers are of high strategic necessities toward the environment preservation acts. Numerous studies have reported the formulation of polylactic acid based bio-degradable micro-composites loaded with natural fibers. However, the use of high natural filler content has been shown to be an underlying challenge in terms of bio-based composites' processability. This study mainly aims at the processability of thermoplastic bio-degradable composites of polylactic acid/Kenaf using a two-roller calendering machine on the melt mixing manner assisted with high shear forces. The results indicated successful processing of the green composites containing 0-30 wt% of kenaf using the sheet forming process from direct mixing of kenaf and polylactic acid granules. It was shown that the tensile modulus increased by 130% and the density of the parts decreased by ~10% at the filler loading of 30 wt% with respect to the neat polylactic acid whilst the tensile strength decreased irrespective of the filler loading. The results further showed the melting temperature decreases supporting better processability by increasing the kenaf fraction. The crystallization against the decrease in the density was correlated to the decrease in the toughness of the parts. Moreover, the morphology and structural studies whilst supporting the changes in mechanical performance supported the effect of processing on the fillers orientation and the possible presence of agglomerated phase at higher filler loadings.https://ajme.aut.ac.ir/article_4717_25f5c00ffede767865bf111ba1d0bfa9.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Investigation of Laser Induced Plasma Assisted Ablation of Glass in Presence of Magnetic Field401414473110.22060/ajme.2022.21086.6027ENNaserAbbasiDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, IranMohammad RezaRazfarDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, IranS.mehdiRezaeiDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, IranKhosroMadanipourDepartment of Physics and Energy Engineering, Amirkabir University of Technology, Tehran, IranMohsenKhajehzadehDepartment of Mechanical Engineering, Amirkabir University of Technology, Tehran, IranJournal Article20220208The present paper is devoted to the study of glass ablation with laser-induced plasma and the effect of the magnetic field on this process. In the experiments, a nanosecond pulsed laser with a wavelength of 532 nm and copper with 2 mm thickness is used as the laser source and the metal substrate respectively. Two permanent neodymium magnets (4500-4800 G) are used to apply an external magnetic field to the drilling zone and to make ablation on the laboratory slide glass. The laser fluence is selected in 4 levels of 1, 1.5, 3, and 3.5 and the characteristics of the holes made with 50 pulse laser radiation are compared in terms of dimensions and morphology. It is observed that by applying a magnetic field, the removed material volume increases about 2 to 2.4 times in the lower fluences and 31 to 35 times in the higher fluences. In the magnetic field absence, for different levels of laser fluence, depth and diameter are changed from 1.6 to 32 and 10 to 100 microns. However, in its presence, they are changed from 3 to 76 and 11 to 380 microns respectively. The shape of deposited particles on glass is also different in the presence and absence of a magnetic field.https://ajme.aut.ac.ir/article_4731_fae978eba30fa332213cd69c8c0dc6a2.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Inverse Reconstruction of Absorption-Coefficient Distribution in a Two-Dimensional Radiative Medium from the Knowledge of Wall Heat Fluxes415426476310.22060/ajme.2022.20599.6008ENMahboubeTanzadeh PanahDepartment of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman, IranSeyed MasoudHoseini SarvariDepartment of Mechanical Engineering, Shahid Bahonar University of Kerman, Kerman, IranJournal Article20210929In this article, an inverse radiation analysis is presented to reconstruct the absorption coefficient distribution from the knowledge of wall heat fluxes for a two-dimensional, absorbing-emitting medium with black walls. The inverse approach aims to find the location of inclusion with a different absorption coefficient. For this purpose, the study is divided into two parts; the direct and the inverse problems. In the direct problem, the radiative transfer equation is solved by the discrete transfer method from the knowledge of the absorption coefficient distribution and we obtain heat fluxes over the walls. Then the measured data are simulated virtually by adding the random errors to heat fluxes. The conjugate gradient method is used to solve the inverse problem to estimate the absorption coefficient distribution. As the measured data are less than the estimated parameters, a multi-step procedure is adopted to restrict the search region. Results show that the absorption coefficient distribution is well recovered in the medium with a low absorption coefficient by a two steps procedure. The results show that the location of inclusion may be found even by noisy data with 1% and 3% measurement errors. However, as the absorption coefficient increases, the location of inclusion is reconstructed in a three steps procedure and the inverse estimation becomes less efficient and time-consuming.https://ajme.aut.ac.ir/article_4763_8a3b667290302e745ef237a26874310f.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Evaluation of Micropolar Fluid Transport through Penetrable Medium: Effect of Flow and Thermal Slip427442478210.22060/ajme.2022.20632.6012ENA. T.AkinshiloDepartment of Mechanical Engineering, University of Lagos, Akoka-Yaba, NigeriaM. G.SobamowoDepartment of Mechanical Engineering, University of Lagos, Akoka-Yaba, NigeriaA.AdingwupuDepartment of Mechanical Engineering, Igbinedion University, Edo, NigeriaJournal Article20211005In this study, the micropolar fluid flow through penetrable walls under slip flow and thermal jump condition is examined. The Micropolar fluid accounts for the hydrodynamic limit of the classical Navier Stokes model, it takes into consideration the micro-structure of the fluid, local structure, and micro rotation of fluid particles. Here the thermal exchange and mass transport of the micropolar fluid are studied considering transport conditions such as radiation, variable magnetism, and nanoparticle concentration. The micropolar fluid flows into the channel and exits under slip velocity and temperature jump condition. The channel walls are assumed porous, fluid is incompressible, Newtonian, and flowing steadily. The mechanics of the fluid is described by coupled, highly successive, nonlinear system of higher-order partial differential equations transformed using appropriate similarity transform to ordinary differentials. These are analyzed by adopting the Homotopy perturbation method of analysis. Results obtained from the analysis show a quantitative increase of nanoparticle concentration from enhanced thermal transfer, which effect is significant towards the lower plate. Similarly, radiation increase reveals higher heat transfer while the Reynolds parameter shows reducing heat transfer. Results obtained compared with similar literature are in good agreement. The study finds good application in tribology, ferrofluids, and arterial blood flow amongst other practical, yet relevant applications.https://ajme.aut.ac.ir/article_4782_8447cda330ec8edc812241f6a4897a2c.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901Triply Periodic Minimal Surfaces Scaffolds and Their Comparison with Cancellous Bone: Fluid Flow Point of View443466481910.22060/ajme.2022.20549.6005ENAliParandvashDepartment of Mechanical Engineering, University of Zanjan, Zanjan, Iran0000-0002-1249-2458MortezaRezaeiDepartment of Mechanical Engineering, University of Zanjan, Zanjan, IranEhsanKhavasiDepartment of Mechanical Engineering, University of Zanjan, Zanjan, IranJournal Article20210913The present study investigated bone growth characteristics, such as permeability, wall shear stress, and surface-to-volume ratio. Then by comparing them with the properties of Cancellous bone, the most desirable scaffolds for bone cell growth have been selected. Nine porous triply periodic minimal surfaces scaffolds in the exact unit cell sizes in four porosities have been designed. Because of the implantation of scaffolds in the body, non-Newtonian fluids can lead to more realistic results. Hence, the non-Newtonian model of the blood has also been examined for comparison with the Newtonian model. The results have shown that the permeability for Newtonian fluids was dependent only on the geometry of the scaffold, and it was intrinsic. Still, in non-Newtonian blood fluid, the permeability has been several times smaller than in the Newtonian model. Also, the average wall shear stress in the non-Newtonian model of blood has been almost twice as large as in the Newtonian model. Finally, by considering the permeability of Cancellous bones ( ), scaffolds which effectively mimicked the characteristics of this type of bone have been identified. The Fischer-Koch S scaffold has the highest permeability among these four scaffolds, and Schwartz Diamond 2 scaffold has the closest permeability to Cancellous bone. This proved that selecting the most desirable scaffold is complex and challenging and should be chosen according to its conditions and application.https://ajme.aut.ac.ir/article_4819_0ada2fcdb23ff30f636b5cd4c158487e.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29376320220901A Parametric Investigation of Melting Process within a Porous Medium under Local Thermal Non-Equilibrium Condition Using Lattice Boltzmann Method467488483310.22060/ajme.2022.20383.5997ENMohammadTaghilouDepartment of Engineering, University of Zanjan, Zanjan, IranSeyed AlirezaSafaviDepartment of Engineering, University of Zanjan, Zanjan, IranJournal Article20210807The use of a porous medium with a high conductivity improves the rate of heat transfer in latent energy storage systems. This paper investigates the melting of the phase change material inside a porous medium under the local thermal non-equilibrium condition with the lattice Boltzmann method. Results examine the effect of Rayleigh number, porosity ratio, pore size, and Sparrow number on the liquid fraction and position of the melting front. Results show that by increasing the pore diameter, the interface of the two phases tends to bend but the liquid fraction decreases. Also, it is found that the difference between the liquid fraction in the presence and absence of natural convection for <em>Ra</em><10<sup>6</sup>, is less than 5%. Nonetheless, by increasing the Rayleigh number to 10<sup>8</sup>, this difference at <em>Fo</em>=0.003 is more than 14% and at <em>Fo</em>=0.006 will reach more than 31%. Furthermore, in <em>Ra</em>=10<sup>8</sup> and for small Sparrow numbers, this difference is small and intensifies with increasing the Sparrow number. Also, by reducing the Darcy number, natural convection is weakened and it can be ignored for <em>Da</em><10<sup>-4</sup>. It is shown that in small Darcy numbers <em>Da</em>=10<sup>-4</sup>, the deviation from the pure conduction is always increased by Sparrow number, and for larger Darcy numbers <em>Da</em>=10<sup>-2</sup>, this deviation has a maximum value of 53% at <em>Fo</em>=0.003 and 84% at <em>Fo</em>=0.006.https://ajme.aut.ac.ir/article_4833_aef7b392fc15163377f2881b48baabb3.pdf