@article { author = {}, title = {ANALYTICAL APPROXIMATE SOLUTION FOR NONLINEAR VIBRATION OF MICROELECTROMECHANICAL SYSTEM USING HE'S FREQUENCY AMPLITUDE FORMULATION}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {83-90}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1739}, abstract = {Abstract– In this paper, nonlinear free vibration of a micro-beam-based micro electro mechanicaloscillator system is studied using He’s frequency amplitude method. Firstly, by considering midplanestretching effects and distributed electrostatic forces and implementing Euler-Bernoullihypothesis, the governing equations are derived. Then, Galerkin method is used to convert theresulted partial differential equations into an ordinary differential one. At last this nonlinearordinary differential equation is solved by He's frequency Amplitude formulation. The proposedmethod offers an analytical closed form solution which is accurate and simple and in order tostudy the problem parametrically and in a more general manner the variables are defined innormalized form. A comparison between the obtained results and the one by an accurate numericalmethod shows the good accuracy of this method in solving this kind of problem. In addition, therelationship between the nonlinear principal frequency and non-dimensional amplitude, electroelasticand axial loads on the beams has been studied.}, keywords = {Nonlinear vibration,microelectromechanical system,Euler-Bernoulli beam,He's frequency amplitude formulation}, url = {https://ijstm.shirazu.ac.ir/article_1739.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1739_2cf97b910d66e5fa89deeba25c6dce16.pdf} } @article { author = {}, title = {VIBRATIONAL ANALYSIS OF DOUBLE-WALLED CARBON NANOTUBES BASED ON THE NONLOCAL DONNELL SHELL THEORY VIA A NEW NUMERICAL APPROACH}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {91-105}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1740}, abstract = {This article describes an investigation into the free vibration of double-walled carbonnanotubes (DWCNTs) using a nonlocal elastic shell model. Eringen’s nonlocal elasticity isimplemented to incorporate the scale effect into the Donnell shell model. Also, the van der Waalsinteraction between the inner and outer nanotubes is taken into account. A new numerical solutionmethod from incorporating the radial point interpolation approximation within the framework ofthe generalized differential quadrature (GDQ) method is developed to solve the problem.DWCNTs with arbitrary layerwise boundary conditions are considered in this paper. It is shownthat applying the local Donnell shell model leads to overestimated results and one must recourse tothe nonlocal version to reduce the relative error. Also, this work reveals that in contrast to thebeam model, the present nonlocal elastic shell model is capable of predicting some new noncoaxialinter-tube resonances in studying the vibrational response of DWCNTs.}, keywords = {Double-walled carbon nanotube,radial point interpolation method,differential quadrature method,layerwise boundary conditions}, url = {https://ijstm.shirazu.ac.ir/article_1740.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1740_18f3b0f5357b2b99229acb9e26c39a86.pdf} } @article { author = {}, title = {LATTICE BOLTZMANN SIMULATION OF NATURAL CONVECTION IN PARTIALLY HEATED CAVITIES UTILIZING KEROSENE/ COBALT FERROFLUID}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {107-118}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1741}, abstract = {In this paper, heat dissipation effect of a ferrofluid on natural convection flow in apartially heated cavity in the presence of an external magnetic field outside of the cavity has beenanalyzed with lattice Boltzmann method (LBM). The cavity is filled with kerosene as the carrierfluid and nanoscale ferromagnetic of cobalt. This study has been carried out for the pertinentparameters in the following ranges: the Rayleigh number of base fluid, Ra=103–105, the volumetricfraction of nanoscale ferromagnetic between 0 and 4%, the size of the nanoscale ferromagnetic isfixed at 45nm. As the size of the heater is equal to H/3, the center of the heater is investigated atYp= 0.25H, 0.5H and 0.75H. Results show that the heat transfer decreases by the increase of thenanoscale ferromagnetic volume fraction for various Rayleigh numbers. The external magneticfield influences the nanoscale ferromagnetic at Ra=104 more than other Raleigh numbers as theleast values are observed at Ra=103. While the heat transfer obtains the greatest value at Yp= 0.5Hfor multifarious Rayleigh numbers, the greatest effect of the nanoscale ferromagnetic for Ra=104and 105 is perceived at Yp= 0.75H.}, keywords = {natural convection,ferrofluid,external magnetic field,cavity,LBM}, url = {https://ijstm.shirazu.ac.ir/article_1741.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1741_8ddfc6b0661587645ce878eb034b2537.pdf} } @article { author = {}, title = {NUMERICAL SIMULATION OF THE MOTION OF DROPS ON AN INCLINED SURFACE}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {119-131}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1742}, abstract = {The flow of two-dimensional drops suspended in an inclined channel is studied bynumerical simulations at non-zero Reynolds numbers. The flow is driven by the acceleration dueto gravity, and there is no pressure gradient in the flow direction. The equilibrium position of adrop is studied as a function of the Reynolds number, the Capillary number, the inclination angleand the density ratio. It is found that the drop always lags the undisturbed flow. More deformabledrops reach a steady state equilibrium position that is farther away from the channel floor. Fordrops that are heavier than the ambient fluid, the equilibrium position moves away from thechannel floor as the Reynolds number is raised. The same trend is observed when the inclinationangle with respect to horizontal direction increases. The behavior agrees with computationalmodeling of chute flow of granular materials. A drop that is lighter than the ambient fluid reachesa steady state equilibrium position closer to the channel floor when the Reynolds number orinclination angle increases. Simulations of 40 drops in a relatively large channel, show that dropsmove away from the channel floor when the density ratio is larger than unity.}, keywords = {Reynolds number,capillary number,density ratio,inclination angle,bond number,equilibrium position}, url = {https://ijstm.shirazu.ac.ir/article_1742.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1742_4e9f92ec68fd5d62710227c298b8cf02.pdf} } @article { author = {}, title = {CANARD-WING INTERACTIONS IN SUBSONIC FLOW}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {133-147}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1743}, abstract = {Extensive subsonic wind tunnel tests were conducted on a coplanar wing-canardconfiguration at various angles of attack. In these experiments, a 60° swept canard was placedupstream of a 60° swept main delta wing. This paper deals with the distribution of mean andfluctuating pressure coefficients on the upper surfaces of both the canard and the wing immersedin a variety of angles of attack. According to the results, presence of canard postpones the vortexformation and growth on the wing to higher angles of attack compared to the canard-off case. Dueto the canard downwash field, the wing operates at lower effective angles of attack and therefore,its vortex breakdown is delayed. The spectral analysis of the unsteady pressure on both the canardand the wing show the existence of narrow, dominant frequency band containing the majority ofthe fluctuation energy. This frequency band is believed to be the natural frequency of the leadingedge vortex. The results show that the dominant frequency of the wing vortex is lower than that ofthe canard having the same sweep angle as the wing, which is an indication of the wing vortexattenuation due to canard downwash field.}, keywords = {Canard,delta wing,pressure power spectrum,leading edge vortex}, url = {https://ijstm.shirazu.ac.ir/article_1743.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1743_c4f1120580ffc384955a5c2fe2ab1b4c.pdf} } @article { author = {}, title = {WARPAGE PREDICTION IN PLASTIC INJECTION MOLDED PART USING ARTIFICIAL NEURAL NETWORK}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {149-160}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1744}, abstract = {The main objective of this paper is to predict the warpage of a circular injection moldedpart based on different processing parameters. The selected part is used as spacers in automotive,transmission, and industrial power generation industries. The second goal is facilitating the setupof injection molding machine without (any) need for trial and error and reducing the setup time. Tomeet these objectives, an artificial neural network (ANN) model was presented. This model iscapable of warpage prediction of injection molded plastic parts based on variable processparameters. Under different settings, the process was simulated by Moldflow and the warpage ofthe part was obtained. Initially, the effects of the melt temperature, holding pressure and the moldtemperature on warpage were numerically analyzed. In the second step, a group of data that hadbeen obtained from analysis results was used for training the ANN model. Also, another group ofdata was applied for testing the amount of ANN model prediction error. Finally, maximum error ofANN prediction was determined. The results show that the R-Squared value for data used fortraining of ANN is 0.997 and for the test data, is 0.995.}, keywords = {Plastic injection molding,warpage,Artificial Neural Network}, url = {https://ijstm.shirazu.ac.ir/article_1744.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1744_b7eb8ed50d88a80fe3a7ade4b30059fb.pdf} } @article { author = {}, title = {AN OPTIMIZED MULTI-STAGE SCHEME TO COORDINATE STEERING AND BRAKING}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {161-174}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1745}, abstract = {A novel Integrated Vehicle Dynamics Control (IVDC) scheme is presented tocoordinate active steering and braking subsystems. The multi-stage coordination scheme is basedon the phase-plane Method. The first stage includes the high-level controller which integrates threeindividual controllers according to vehicle states in the phase plane. In the next stage, an optimizedscheme is established to allocate the control objectives to individual braking and steering forces.To achieve this, an inequality-constrained optimization problem, including driver's brake demand,is solved analytically. Coefficients of the cost function are adapted based on the vehicle phaseplanetrajectory to realize a proper coordination of braking and steering subsystems. Simulationresults validate the effectiveness of the proposed method to enhance the vehicle dynamics control.}, keywords = {Coordinated,vehicle dynamics,active steering,wheel braking,optimal,tire force distribution,phaseplane method}, url = {https://ijstm.shirazu.ac.ir/article_1745.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1745_61e485c99137157777cd1b43b2ec80b4.pdf} } @article { author = {}, title = {MULTI OBJECTIVE OPTIMIZATION OF FLUX CORED ARC WELD PARAMETERS USING FUZZY BASED DESIRABILITY FUNCTION}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {175-187}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1746}, abstract = {In recent years much research has been conducted to study the variations in weldingparameters and consumables on the mechanical properties of steels to optimize weld integrity. Thequality of weld is a very important working aspect for the manufacturing and constructionindustries. In the present work, an attempt has been made to apply an efficient technique, fuzzybased desirability method to solve correlated multiple response optimization problems, in the fieldof flux cored arc welding. This approach converts the complex multiple objectives into a singlefuzzy reasoning grade. Based on fuzzy reasoning grade, optimum levels of parameters (Weldingcurrent, arc voltage and electrode stickout) were identified. Experiments were performed based onTaguchi method. Weld bead hardness and material deposition rate are selected as quality targets.Significant contributions of parameters are estimated using Analysis of Variance (ANOVA).Confirmation test is conducted and reported. It is found that the electrode stickout is the mostsignificant controlled factor for the process according to the weighted fuzzy reasoning grade of themaximum weld bead hardness and material deposition rate. The proposed technique allowsmanufacturers to develop intelligent manufacturing system to achieve the highest level ofautomation.}, keywords = {ANOVA,Deposition rate,Desirability,Flux cored arc welding,fuzzy,orthogonal array}, url = {https://ijstm.shirazu.ac.ir/article_1746.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1746_58f35f9461137bdead5b179d46580f48.pdf} } @article { author = {}, title = {OPTIMIZATION OF DIE PROFILE FOR COLD FORWARD EXTRUSION USING AN IMPROVED SLAB METHOD ANALYSIS}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {189-202}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1747}, abstract = {One of the most important design parameters in extrusion process is the shape of dieprofile. In the present research work, an optimum extrusion die profile has been obtained throughimplementation of slab analysis in a computational algorithm. Moreover, extrusion processthrough both optimum conical and curved die has been performed experimentally and also byfinite element method. It has been demonstrated that material work hardening characteristics andfriction condition have remarkable effects on the optimum streamlined die profile. Also, resultsprove that the streamlined die profile designed based on the developed approach, is superior to theconventional conical dies from both metallurgical and manufacturing perspectives. Consequently,the proposed method can be regarded as an efficient and reliable tool for designing streamlined dieprofiles. Hence, this technique can be used to produce desirable conditions in both process andproduct quality in terms of extrusion force, deformation homogeneity and die wear.}, keywords = {Extrusion,die profile,Finite Element Analysis,slab method,Strain distribution}, url = {https://ijstm.shirazu.ac.ir/article_1747.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1747_62f2c6646425f7f859a0b9e99a2d2343.pdf} } @article { author = {}, title = {OPTIMIZATION OF SPECIFIC DIE PROFILES IN THIN WALLED TUBE EXTRUSION}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {203-215}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1748}, abstract = {In the present work, three extrusion profiles have been investigated objectively, theseare a conical, a cosine which is proposed in this study and a profile designed to impose equal strainincrements over the equi-spaced sections. Each of them reduces a portion of the required power forextrusion. Conical profile provides the least frictional surface, cosine profile omits the surfaces ofvelocity discontinuity and the other profile reduces the power attributed to redundancy duringdeformation. However, the capability of these profiles in reducing the total power of the process isvery different. Results suggest that cosine profile is the best energy-wise, whereas the profilewhich imposes equal strain increments over the equi-spaced sections provides the best distributionof strain in the product. In addition, a simple exponential equation as a function of die geometry ispresented for the case of the profile which imposes equal strain increments over the equi-spacedsections.}, keywords = {Tube extrusion,upper-bound method,Finite element method,power optimization,die profile}, url = {https://ijstm.shirazu.ac.ir/article_1748.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1748_43b11dbad8c9226f3a9823c133566c92.pdf} } @article { author = {}, title = {ESTIMATION OF THE BREAKUP LENGTH FOR THE ANNULAR AND THE ROUND LIQUID JET USING LINEAR INSTABILITY ANALYSIS}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {217-232}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1749}, abstract = {A linear instability analysis of an inviscid annular liquid sheet emanating from anatomizer subjected to inner and outer swirling air streams and a non-swirl round liquid jet has beencarried out. The dimensionless dispersion equation that governs the instability was derived andwas solved by Numerical method to investigate the effects of the liquid-gas swirl orientation onthe maximum growth rate and its corresponding unstable wave number that produces the finestdroplets. To understand the effect of air swirl orientation with respect to liquid swirl direction, fourpossible combinations with both swirling air streams with respect to the liquid swirl direction havebeen considered. Results show that at low liquid swirl Weber number a combination of co-innerair stream and counter-outer air stream has the largest most unstable wave number and shortestbreakup length. The combination of inner and the outer air stream co-rotating with the liquid hasthe highest growth rate. Also, the results for round liquid jet and planar liquid sheet show that thelinear theory accurately predicts the variation in breakup length with jet velocity.}, keywords = {Annular sheet,round jet,atomization,linear analysis,instability,swirl}, url = {https://ijstm.shirazu.ac.ir/article_1749.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1749_a299c8dc853ae502f4bb79704c79dbc6.pdf} } @article { author = {}, title = {EXPERIMENTAL, NUMERICAL ANALYSIS AND OPTIMIZATION OF ELLIPTICAL ANNULAR FINS UNDER FREE CONVECTION}, journal = {Iranian Journal of Science and Technology Transactions of Mechanical Engineering}, volume = {37}, number = {2}, pages = {233-239}, year = {2013}, publisher = {Shiraz University}, issn = {2228-6187}, eissn = {}, doi = {10.22099/ijstm.2013.1750}, abstract = {This paper presents the total heat transfer rate by Elliptical Annular Fin (EAF) andCircular Annular Fin (CAF) by experimental set-up, validated CFD analysis and optimization ofEAF using Genetic Algorithm (GA). The experimental result of EAF shows that, the surfacetemperature of EAF goes on decreasing gradually along with the projected surface area in thedirection of the major axis. The STE decreases with the Biot number (Bi) and Shape factor (SF).The rate of reduction of STE with increasing Bi is higher for Bi < 0.013. The experimental resultsare validated with CFD result. The deviation is within acceptable range for surface temperature,STE and fin effectiveness are 5-8%. The GA developed is validated with the experimental result. Itis observed that, the fin effectiveness is higher when the minor axis touches the circumference ofthe CT, and for smaller values of SF and smaller values of the radius of the CT. This optimizationmethod is universal and may be used for optimization of EAF under specified volume.}, keywords = {Axis ratio,biot number,elliptical annular fin,fin effectiveness,heat transfer coefficient}, url = {https://ijstm.shirazu.ac.ir/article_1750.html}, eprint = {https://ijstm.shirazu.ac.ir/article_1750_6079798584e972a755467feee369e72c.pdf} }