2018-08-21T03:24:08+04:30
http://journals.modares.ac.ir/browse.php?mag_id=101&slc_lang=fa&sid=15
101-12304
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Editorial
2011
9
01
0
0
http://journals.modares.ac.ir/article-15-12304-en.pdf
101-8163
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
BE and analytical model of sound transmission
through an automotive muffler shell
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 FEM-BEM 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.
Muffler
Sound Transmission
Boundary Element Method (BEM)
SYSNOISE
2011
9
01
1
11
http://journals.modares.ac.ir/article-15-8163-en.pdf
101-3547
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Comparison of numerical methods in perpendicular and inclined bird strike events
reza
Hedayati
Saeed
Ziaee Rad
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.
Perpendicular and inclined bird impact
Lagrangian method
SPH method
ALE method
2011
9
01
13
25
http://journals.modares.ac.ir/article-15-3547-en.pdf
101-6547
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Three-Dimensional Simulation of Entrance Region effect for Viscoelastic flows in a Rectangular Duct
Ali
Jalali
Mohammad Hassan
Kayhani
mahmood
norouzi
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 three-dimensional 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 three-dimensionality 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.
developing flow
three-dimensional modeling
PTT constitutive equation
Viscoelasic fluid
2011
9
01
27
37
http://journals.modares.ac.ir/article-15-6547-en.pdf
101-3381
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Analytical and Experimental Investigation of the Effects of Spot Weld Diameter, Gap Distance and Electrode Force on the Mixed Mode of Resistance Spot Welded-Joints
The effects of mixed mode fracture and fatigue crack path have been investigated in tensile-shear spot weld specimens having different gaps between their sheets. Non-linear 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.
Fatigue Life
Spot welded joint
fatigue crack growth
Mixed mode fracture
Volumetric method
2011
9
01
39
48
http://journals.modares.ac.ir/article-15-3381-en.pdf
101-8574
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Finite element analysis and experimental investigation on gas forming of hot aluminum alloy sheet
maedeh
zoei
mahmoud
farzin
amirhosein
mohammadi
Aluminum alloys are desirable in industry due to their excellent high-strength 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.
Hot forming
Bulge forming
Aluminum alloy
Finite element analysis
2011
9
01
49
56
http://journals.modares.ac.ir/article-15-8574-en.pdf
101-3413
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Design and Manufacturing Magnetic Damper and Active Control of Beam Vibrations using Eddy current
ALI
MADDAH
y
hojat
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 non-contacting 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
Modal Analysis
Simulation
Eddy Current impact
FFT
2011
9
01
57
66
http://journals.modares.ac.ir/article-15-3413-en.pdf
101-5951
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Investigation on Aluminum Closed Cell Foams through Accumulative Roll Bonding with TiH2 as Blowing Agent
h
f
Esmaeil
Emadoddin
Ali
• Habibolahzadeh
- In this study, Aluminum closed-cell 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.
"closed-cell foam"
"titanium hydride"
"temperature of foaming"
"time of foaming"
2011
9
01
67
75
http://journals.modares.ac.ir/article-15-5951-en.pdf
101-3491
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Generation of Typical Meteorological Year for Tehran
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 14-year 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.
Simulation
Typical Meteorological Year
Building
energy consumption
2011
9
01
77
91
http://journals.modares.ac.ir/article-15-3491-en.pdf
101-5709
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Analysis of Free Vibrations of Moderately Thick Cylindrical Shells Made of Functionally Graded Materials Using Differential Quadrature Method
komeil
khorami
sh
h
- 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
Weighting Coefficients
Grid Points
Natural frequency
Volume Fraction
2011
9
01
93
106
http://journals.modares.ac.ir/article-15-5709-en.pdf
101-6257
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Hydrodynamic Instability Criterion of Two-Phase Flow Using PFM Model
behzad
faramarzi
mohamadreza
ansari
Abstract: Applications of two-phase 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 two-phase flow approach to numerical analysis. Two-fluid model is the most widely used and most accurate model for predicting two-phase 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 well-posed condition; otherwise the model is in ill-posed condition and the results are unstable numerically. Hydrodynamic instability of two-phase gas-liquid by using the PFM model is calculated and discussed.
Two phase flow
Illposed and Wellposed
Kelvin-Helmholtz
interface instability
2011
9
01
107
118
http://journals.modares.ac.ir/article-15-6257-en.pdf
101-9680
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Natural Convection in a Square Cavity with a Heated Obstacle Using Lattice Boltzmann Method
Mohsen
Nazari
- 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 Navier-Stokes equation can be derived from the lattice Boltzmann equation through the Chapman-Enskog 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 two-dimensional. 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.
Natural Convection Heat Transfer
Lattice Boltzmann Method
Obstacle
Cavity
2011
9
01
119
133
http://journals.modares.ac.ir/article-15-9680-en.pdf
101-6162
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Investigating the Effects of Tool Materials on the Properties of Electrical Discharge Machining of γ–TiAl Intermetallic
Behzad
Jabbaripour
m
sadeghi
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.
γ–TiAl Intermetallic
Material Removal Rate
Tool Wear Ratio
Surface Topography
Electrical Discharge Machining
2011
9
01
135
146
http://journals.modares.ac.ir/article-15-6162-en.pdf
101-1022
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Investigation of Greenhouse’s Thermal Performance in Residential Buildings of Cold Climate Case Study: City of Ardebil
Sara
Gilani
Behrouz
Mohammad Kari
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.
Building
Energy efficiency
Solar Systems
Passive
Greenhouse
2011
9
01
147
157
http://journals.modares.ac.ir/article-15-1022-en.pdf
101-223
2018-08-21
10.1002
Modares Mechanical Engineering
IQBQ
1027-5940
2476-6909
2011
11
2
Path Planning for a Planar Hyper-Redundant Manipulator with Lockable Joints Using Particle Swarm Optimization
Hassan
Salarieh
In this paper, the problem of path planning for a special hyper-redundant manipulator with lockable joints is solved using particle swarm optimization. Two strategies have been used. In the first strategy, the path-planning 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 multi-objective 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.
optimization
path planning
Redundant manipulators
Particle Swarm Optimization
2011
9
01
159
175
http://journals.modares.ac.ir/article-15-223-en.pdf