Editorial
text
article
2011
per
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
http://mme.modares.ac.ir/article_1439_dd8d1a0fa46120f9e359a954109d8677.pdf
BE and analytical model of sound transmission
through an automotive muffler shell
روح الله
طالبی توتی
استادیار/دانشگاه علم و صنعت ایران
author
محمد حسن
شجاعی فرد
استاد/ دانشگاه علم و صنعت ایران
author
عارف
یداللهی
محقق/ دانشگاه علم و صنعت ایران
author
text
article
2011
per
In this study, TL characteristics of muffler shells are simulated using analytical and numerical model. Noise generated by engines, is radiated out into the atmosphere at the radiation end of the muffler and also from the shell of the muffler. So, accurate prediction of sound radiation characteristics from muffler shells is of significant importance in automotive exhaust system design. In analytical method, an exact solution is obtained by solving the vibration equation of the shell and acoustic wave equations simultaneously. Then, in numerical model, with the aid of SYSNOISE, commonly used commercial boundary element software, the coupled structural FEMBEM model is applied to predict the TL of muffler shell. The predicted results agreed reasonably well with the experimental results. The effects of important design parameters likes thickness and geometrical shape are studied to provide design guidelines.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
1
11
http://mme.modares.ac.ir/article_1421_1c6b4b985a2853322e1449f7583d2e29.pdf
Comparison of numerical methods in perpendicular and inclined bird strike events
reza
Hedayati
Isfahan University of Technology
author
Saeed
Ziaee Rad
استاد دانشگاه صنعتی اصفهان
author
text
article
2011
per
Collisions between a bird and an aircraft, known as “bird strike event” is a common and dangerous phenomenon in aviation industry. In this study, three numerical methods namely Lagrange, Smoothed Particles Hydrodynamics (SPH) and Arbitrary Lagrangian Eulerian (ALE) have been implemented in order to investigate bird strike incident. The results have been compared with each other and also with exeperimental data. In order to compare the results obtained from three methods, pressures at the center of impact and also deformation of bird models have been compared. Results indicate that all the three methods are able to predict the pressure at the center of impact almost accurately in both perpendicular and inclined impacts. In addition to that all the methods are able to predict same deformation of bird at particular time intervals. Shorter solution time, not having much parameters to deal with and low probability of numerical errors make the SPH method as a good candidate to analyze bird strike problems.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
13
25
http://mme.modares.ac.ir/article_1422_508b824db9adc4baee518e1b4efb3bee.pdf
ThreeDimensional Simulation of Entrance Region effect for Viscoelastic flows in a Rectangular Duct
Ali
Jalali
Shahrood university of technologh
author
Mohammad Hassan
Kayhani
shahrood university of technologh
author
mahmood
norouzi
shahrood university of thechnology
author
text
article
2011
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In this paper, numerical 3D simulation of viscoelastic developing flow in a rectangular duct with the nonlinear constitutive equation was considered.
So far, researchers have focused on the fully developed zone. In these cases, the effects of entrance region of flow and changes in important quantities of developing flow were neglected. Therefore threedimensional modeling of the entrance region is an innovation of this work. For modeling the stress term,PTT constitutive equation which is one of the most perfect models was used. It should be noted that, the Oldroyd conditions was ingratiated and secondary flow has been simulated.
Considering threedimensionality of the solution domain as well as the dependency and nonlinearity of equations, artificial compressibility explicit method and staggered grid for solving the equations is purposed.
The result is in good agreement with the others reported in the fully developed region.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
27
37
http://mme.modares.ac.ir/article_1423_e1bcb7112b3634f46d5c004d8b223027.pdf
Analytical and Experimental Investigation of the Effects of Spot Weld Diameter, Gap Distance and Electrode Force on the Mixed Mode of Resistance Spot WeldedJoints
سوران
حسنی فرد
author
text
article
2011
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The effects of mixed mode fracture and fatigue crack path have been investigated in tensileshear spot weld specimens having different gaps between their sheets. Nonlinear analysis has been performed to obtain the stress distributions along the line perpendicular to the fatigue crack path. The amounts of effective stress and notch strength reduction factors have been obtained using the volumetric method. Fatigue crack growth approach has been applied to obtain stress intensity factors in mode I and mode II of fracture and to estimate fatigue crack propagation of spot welds. The results obtained from numerical predictions such as the volumetric method and the fatigue crack growth approach have been compared with the available fatigue test data. The results obtained from the fatigue crack growth approach show that spot weld specimens with bigger nugget diameter have the smaller values of stress intensity factors compared with those spot welds with smaller nugget diameters. However, with due attention to the fact that fatigue cracks propagate in the mixed mode condition, the ratio of mode I stress intensity factor to the mode II become more important parameter while predicting the fatigue life of specimens.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
39
48
http://mme.modares.ac.ir/article_1424_c48c05a81d71cff611e29a707524c0c3.pdf
Finite element analysis and experimental investigation on gas forming of hot aluminum alloy sheet
maedeh
zoei
پژوهشگر ارشد
author
mahmoud
farzin
دانشیاردانشکده مهندسی مکانیکدانشگاه صنعتی اصفهانکدپستی84156
author
amirhosein
mohammadi
پژوهشگر ارشد
author
text
article
2011
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Aluminum alloys are desirable in industry due to their excellent highstrength to weight ratio, corrosion resistance, and weldability. However, at room temperature, the formability and the surface quality of the final product of these alloys are low. So in recent decade, new process, hot metal gas forming, has been introduced. This paper investigated new method of hot aluminum alloys forming using gas. Experimental test for bulge forming was designed and made. In addition to experimental test, finite element analysis of process was done. Results showed that hot metal gas forming provides highest forming temperature for aluminum alloy blank and with increasing blank temperature up to optimum temperature of hot forming, there is reduced pressure forming and significant improvement of formability. Results of experimental test and finite element analysis including determination of optimum temperature for forming of special aluminum alloy, maximum formability in this process, required forming pressure, minimum thickness, thickness and temperature distribution were conformed.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
49
56
http://mme.modares.ac.ir/article_1425_92ce8e0c0f322fafb0bc806c39f65119.pdf
Design and Manufacturing Magnetic Damper and Active Control of Beam Vibrations using Eddy current
ALI
MADDAH
بورسیه دکتری دانشگاه سمنان
author
y
hojat
دانشگاه تربیت مدرس
author
text
article
2011
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Abstact There exist many methods of adding damping to a vibrating structure; however, very few can
function without ever coming into contact with the structure. One such method is eddy current damping. This magnetic damping scheme functions through the eddy currents that are generated in a nonmagnetic conductive material when it is subjected to a time changing magnetic field. in this research work a variable eddy current damper is applied for controlling the vibrations of a cantilever beam. An displacement sensor is attached to the setup for measuring the feedback response for controlling system. A PID control algorithm is developed for the controlling system as the eddy current damper is a noncontacting system. Using this system, experiments are performed on a cantilever beam showing the system can effectively suppress each of the first three modes of vibration by upwards of 10 dB, demonstrating the actuator has an increased bandwidth over previously used eddy current methods.
Keywors: Eddy Currents, Magnetic Dampers, FFT
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
57
66
http://mme.modares.ac.ir/article_1426_ee9805715395db5cc94716b94f775906.pdf
Investigation on Aluminum Closed Cell Foams through Accumulative Roll Bonding with TiH2 as Blowing Agent
h
f
s
author
Esmaeil
Emadoddin
دانشگاه سمنان
author
Ali
• Habibolahzadeh
دانشگاه سمنان
author
text
article
2011
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 In this study, Aluminum closedcell foam was produced through accumulative roll bonding using TiH2 as blowing agent. Then, the effect of the number of rolling passes, foaming temperature, foaming time and heating rate on percent of porosity was investigated. The results indicate that foaming process improves with increasing temperature. The TiH2 powder was uniformly dispersed into the matrix with increasing the number of roll passes and caused an increase of the percent of porosity. Finally, 41% of porosity at foaming temperature of 680°C, foaming time of 5 min and heating rate of 10(°C)/s was produced.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
67
75
http://mme.modares.ac.ir/article_1417_f18ff6a4cf03108afa70e7d481421f76.pdf
Generation of Typical Meteorological Year for Tehran
عبدالسلام
ابراهیم پور
عضو هیئت علمی
author
مهدی
معرفت
دانشکده مهندسی مکانیک، دانشگاه تربیت مدرس ، عضو هیئت علمی(دانشیار)
author
text
article
2011
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Abstract The correct selection of typical meteorological year is an important factor for accurate building energy simulation. In this study, the Sandia method has been applied to analyze the measured weather data of a 14year period (1992–2005) in Tehran and to select the proper data for the typical meteorological year. Also, typical meteorological year has been generated by using the Meteonorm and Weathergenrator softwares. Then the results of the Sandia method and the two mentioned softwares have been compared with long term average measured data for main parameters in the weather data file. It was found that, the results of the Sandia method has good agreement with the long term average measured data but the created TMY data by the Weathergenrator and Meteonorm softwares have not good agreement with the long term average measured data.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
77
91
http://mme.modares.ac.ir/article_1419_f4847584b9c2b8b6f65488c0de7893f8.pdf
Analysis of Free Vibrations of Moderately Thick Cylindrical Shells Made of Functionally Graded Materials Using Differential Quadrature Method
komeil
khorami
دانشجوی کارشناسی ارشد مهندسی مکانیکدانشگاه علم و صنعت ایران
author
sh
h
t
author
text
article
2011
per
 In this paper vibration frequency characteristics of functionally graded cylindrical (FGM) shells are investigated using the differential quadrature method (DQM). The essence of the differential quadrature method is that the partial derivative of a smooth function with respect to a variable is approximated by a weighted sum of function values at all discrete points in that direction. Its weighting coefficients are not related to any special problem and only depend on the grid points and the derivative order. The material properties are graded in the thickness direction of the shell according to the volume fraction power law distribution. The fast convergence behavior of the method is demonstrated and its accuracy is verified by comparing the results with those of other shell theories obtained using conventional methods and also with those of ABAQUS software. Effects of the exponential volume fraction law on the natural frequencies of FGM cylindrical shells for classical boundary conditions (all possible combinations of clamped (C) and simply supported (S) boundary conditions) are studied against circumferential wave number, length to radius ratio and thickness to radius ratio for different values of power law exponents
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
93
106
http://mme.modares.ac.ir/article_1418_3c4f2d83542a0b97c1b0c4118bb74b5c.pdf
Hydrodynamic Instability Criterion of TwoPhase Flow Using PFM Model
behzad
faramarzi
piroozi .st. 3rd nirooye havayi. 3.22. no33
author
mohamadreza
ansari

author
text
article
2011
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Abstract: Applications of twophase flow in nuclear power plants, transmission lines, oil and gas have been considered in recent decades. Different models have been introduced that can contribute to the current twophase flow approach to numerical analysis. Twofluid model is the most widely used and most accurate model for predicting twophase flow in channels during different regimes of unstable flow. This study addressed the PFM model Hyperbolicity. Hyperbolicity of this model is the most important for the wellposed condition; otherwise the model is in illposed condition and the results are unstable numerically. Hydrodynamic instability of twophase gasliquid by using the PFM model is calculated and discussed.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
107
118
http://mme.modares.ac.ir/article_1427_b95347e1bdb5a7b5d3782dc7783edb31.pdf
Natural Convection in a Square Cavity with a Heated Obstacle Using Lattice Boltzmann Method
Mohsen
Nazari
Assistant Prof. of Mechanical Eng.
Shahrood Univ. of Technology
author
سپیده
رمضانی
دانشگاه صنعتی شاهرود
author
text
article
2011
per
 Natural convection heat transfer in a square cavity induced by heated plate is investigated using the lattice Boltzmann method. A suitable forcing term is represented in the Boltzmann equation. With the representation, the NavierStokes equation can be derived from the lattice Boltzmann equation through the ChapmanEnskog expansion. Top and bottom of the cavity are adiabatic; the two vertical walls of the cavity have constant temperatures lower than the plate’s temperature. The flow is assumed to be twodimensional. Air is chosen as a working fluid (Pr=0.71). The study is performed for different values of Grashof number ranging from 103 to 105 for different aspect ratios and position of heated plate. The effect of the position and aspect ratio of heated plate on heat transfer are discussed. With increase of the Grashof number, heat transfer rate is increased in both vertical and horizontal position of the plate. The obtained results of the lattice Boltzmann method are validated with those presented in the literature.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
119
133
http://mme.modares.ac.ir/article_1430_46ff0dada34af7a7448929172d905340.pdf
Investigating the Effects of Tool Materials on the Properties of Electrical Discharge Machining of γ–TiAl Intermetallic
Behzad
Jabbaripour
Tarbiat Modares University
author
m
sadeghi
tmu
author
محمدرضا
شبگرد
عضو هیت علمیدانشگاه تبریز
author
شاهرخ
فریدوند
دانشگاه تربیت مدرس
author
text
article
2011
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Due to outstanding properties of γ–TiAl intermetallic such as high resistance against fatigue, oxidation, corrosion, creep, dynamic vibration, high working temperature and also its application in aerospace and automotive industry, turbojet engines and blade manufacturing; in this paper, electrical discharge machining (EDM) of γ–TiAl intermetallic by means of three kinds of tool electrodes including copper, graphite and aluminum is investigated, to compare the output characteristics of the machining process such as material removal rate, tool wear ratio, surface roughness and topography and EDS elemental analysis of machined surfaces. The results indicate that major elements in chemical composition of γ–TiAl machined surfaces are including titanium, aluminum, carbon and oxygen. The variation of tool material has not significant effect on formation of different chemical compounds and phases or in other words surface modification of machined surface. While it mainly affects other aspects of output characteristics such as material removal rate, tool wear ratio and surface roughness.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
135
146
http://mme.modares.ac.ir/article_1429_30694aa1bf1a720ea05e75ea0d1cb12e.pdf
Investigation of Greenhouse’s Thermal Performance in Residential Buildings of Cold Climate Case Study: City of Ardebil
Sara
Gilani
PhD Student in Architecture, Faculty of Architecture, College of Fine Arts, University of Tehran
author
Behrouz
Mohammad Kari
Assistant Professor in Building Physics, Building and Housing Research Center
author
text
article
2011
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Solar energy can be utilized through different types of passive and active solar systems. One of the passive systems is the Greenhouse that provides different functions. In this research, heating performance of Greenhouse in cold climate is simulated, investigated, and analyzed by means of computer software.
The results of this research showed that Greenhouse, in comparison with Direct Gain glazing system, decreases building heating load, despite the diminution of the direct radiation gains. In Ardebil, the optimal building orientation, in order to get the maximum solar gain and the minimum load in the heating period, is obtained in south west and west direction of the facade. The maximum heat loss and minimum solar gain occur through the north side of the building, which is considered as the most inappropriate facade direction for the Greenhouse system.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
147
157
http://mme.modares.ac.ir/article_1420_e25c035582e8d15f8dc70e209a5f5ee7.pdf
Path Planning for a Planar HyperRedundant Manipulator with Lockable Joints Using Particle Swarm Optimization
علی
طاهری فر
دانشگاه شریف
author
Hassan
Salarieh
استادیار/ دانشگاه شریف، دانشکده مکانیک
author
آریا
الستی
استاد/ دانشگاه شریف
author
مهرداد
بروشکی
استادیار/ دانشگاه شریف
author
text
article
2011
per
In this paper, the problem of path planning for a special hyperredundant manipulator with lockable joints is solved using particle swarm optimization. Two strategies have been used. In the first strategy, the pathplanning problem is solved in two stages; first, the inverse kinematics of manipulator is solved with continuous PSO and then the sequence of switching is optimized by modified discrete PSO. The results of discrete PSO are compared to discrete GA to show the effectiveness of the discrete PSO. In order to implement multiobjective optimization in inverse kinematics calculation, linear fitness function and Vector Evaluated PSO (VEPSO) are used. In the second strategy, a novel approach in particle swarm optimization is proposed. In this approach, the integer and continuous value numbers are joined together in a single particle to form a hybrid particle. The results of two strategies were compared to show the convergence speed and performance of the second strategy which was proposed here.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
11
v.
2
no.
2011
159
175
http://mme.modares.ac.ir/article_1428_72aa38cf283b441397ed75c6f6812d1f.pdf