
text
article
2012
per

Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
0
0
http://mme.modares.ac.ir/article_1531_540c6dee0f8c592617c0c5dbfe955f89.pdf
Interface Modeling of Nanotube Reinforced Nanocomposites by Using MultiScale Modeling Method
Mahnaz
Zakeri
هیات علمی/ دانشکده هوافضا، دانشگاه صنعتی خواجه نصیرالدین طوسی
author
مهدی
شایانمهر
دانشگاه صنعتی خواجه نصیرالدین طوسی
author
محمود مهرداد
شکریه
هیات علمی/دانشگاه علم و صنعت ایران
author
text
article
2012
per
Studying of connection between a carbon nanotube (CNT) and its surrounding matrix is an important issue in investigation of the behavior of nanocomposites reinforced with carbon nanotubes. In this paper, the carbon nanotube and its surrounding matrix is considered as a volume element and its mechanical behavior is analyzed using finite element method. Interface joints are modeled utilizing nonlinear spring elements; and effective force between CNT and matrix is determined based on LennardJones equation. The interface thickness is changed between 1.73.8Am, to study its effect on the volume element behavior. Tensile loading of volume element is applied in two ways to investigate the perfect connection between nanotube and matrix. Subsequently, tensile longitudinal elastic modulus of volume elements with different aspect ratios of nanotube and thickness of interface are calculated and compared with the results of rule of mixture theory in micro mechanics field. The results of this research indicate that for low aspect ratios, the amount of elastic modulus is near to individual resin or nanotube. But, increasing the aspect ratio causes the connections to be more efficient and results converge to rule of mixture
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
1
11
http://mme.modares.ac.ir/article_1517_5e8d4b906ec08bf72eaa945efa87f91f.pdf
Inverse dynamics of nonholonomic wheeled mobile robotic manipulators using recursive GibbsAppell formulation
Moharam
Habibnejad Korayem
Prof. of Mechanical Eng. of Iran University of Science and Technology
author
ali
shafei
PhD candidate / Iran University of Science and Technology
author
text
article
2012
per
The main purpose of this paper is to derive the inverse dynamic equation of motion of nrigid robotic manipulator that mounted on a mobile platform, systematically. To avoid the Lagrange multipliers associated with the nonholonomic constraints the approach of GibbsAppell formulation in recursive form is adopted. For modeling the system completely and precisely the dynamic interactions between the manipulator and the mobile platform as well as both nonholonomic constraints associated with the noslipping and the noskidding conditions are also included. In order to reduce the computational complexity, all the mathematical operations are done by only 3×3 and 3×1 matrices. Also, all dynamic characteristics of a link are expressed in the same link local coordinate system. Finally, a computational simulation for a manipulator with five revolute joints that mounted on a mobile platform is presented to show the ability of this algorithm in generating the equation of motion of mobile robotic manipulators with high degree of freedom.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
12
21
http://mme.modares.ac.ir/article_1518_e0618e44ca6d6977afeaeb87e350174f.pdf
Optimal Design of PlateFin Heat Exchangers by a Bees Algorithm
حسین
زارع
دانشگاه شهید چمران
author
سالم
بعنونی
دانشگاه شهید چمران
author
افشین
قنبرزاده
دانشگاه شهید چمران
author
text
article
2012
per
This study explores application of a bees algorithm (BA) for economic optimal design of platefin heat exchangers. Therefore in this study, the optimization is targeting two singleobjective functions separately. The first is the minimum heat transfer area which is mainly associated with the capital cost of the heat exchanger and the other is minimum total pressure drop that represents the operating cost for specific heat duty requirement under given space restrictions. Based on applications, heat exchanger length, fin frequency, numbers of fin layers, lance length of fin, fin height and fin thickness of the heat exchanger are considered for optimization. The constraints are handled by penalty function method. Also, the effectiveness and accuracy ofthe proposed algorithm is demonstrated through a case study. Comparing the results with the corresponding results using genetic algorithm (GA)and particle swarm optimization (PSO) algorithm reveals that the bees algorithm can converge to optimum solution with higher accuracy
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
22
29
http://mme.modares.ac.ir/article_1519_24ca7017fd445cb7a1c9e31107466f56.pdf
Experimental and Numerical Investigation of Unsteady Turbulent Flow in a Fluidic Oscillator Flow Meter with Derivation of Characteristic Diagram
Hamid
Madadkon
M.Sc. Student, Isfahan University of Technology
author
Alireza
Fadaei Tehrani
Associate Prof., Dept. of Mechanical Engineering, Isfahan Univ. of Tech.
author
Mahdi
Nili Ahmadabadi
Assistant Prof. ,Dept. of Mechanical Engineering, Isfahan Univ. of Tech.
author
text
article
2012
per
In this article, a special duct is introduced in which, inlet water jet initiates to oscillate after a short time and it causes the velocity and pressure to oscillate regularly. Considering that there is a linear relationship between the inlet jet velocity and its oscillations frequency, the flow rate can be calculated by measuring the pressure frequency. In order to study the flow field inside the current geometry of fluidic oscillator and also to find the optimum location for sensor to detect the pressure oscillation, the unsteady turbulent NavierStokes equations are solved by ANSYS CFX software. Having studied the grid independency, capability of Kε and SST turbulence models for numerical simulation of unsteady flow inside the fluidic oscillator is considered. Then, according to the peak to average ratio (PAR) criterion, the qualities of pressure signals are compared at some points, to distinguish an optimum pressure sensor position. Afterwards, a prototype of fluidic oscillator flow meter is manufactured for the first time in Iran. Using this prototype and inserting the pressure and Piezoelectric sensor at the optimum point, the numerical simulation results are validated by the experimental data. Comparison between the numerical and experimental results shows that the SST model is more suitable for this flow simulation. Finally, by performing experiments in different flows, acquiring and processing pressure signals, the flow meter characteristic diagram (inlet jet oscillations frequency inlet jet velocity) are extracted.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
30
42
http://mme.modares.ac.ir/article_1520_02409246be27b1eed2fcbac0d5a1d358.pdf
Analysis of reactant transport and pressure drop in a PEM fuel cell cathode with partially blocked flow channel
ابراهیم
افشاری
استادیار/دانشگاه اصفهان
author
Nasser
Baharloo Hooreh
دانشجوی کارشناسی ارشد/ دانشگاه اصفهان
author
text
article
2012
per
In this study, the geometrical changes at cathode electrode in proton exchange membrane (PEM) fuel cell has been considered by inserting baffle plates across the channel. The effects of the blockage with various gap ratios, shape, thickness and numbers of the baffle plates, and the porosity of the diffusion layer on the oxygen transport and the pressure drop across the channel length are explored. It is revealed that partially blocked oxygen channel with rectangular baffle has the most velocity and oxygen concentration in the gas diffusion layer/catalyst layer interface than that of the other shape of plates; however results in a penalty of high pressureloss. Increasing the porosity of gas diffusion layer (GDL), baffle plate thickness and baffle number and/or reducing the gap size in order to enhance the reactant gas transport result in pressure loss. Here, among the parameters considered, the porosity of GDL, gap ratio and plate number have the most remarkable impact on the oxygen transport to GDL and variation in pressure drop.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
43
58
http://mme.modares.ac.ir/article_1521_f52be9e73c5a7e5780cc0f9501c366bf.pdf
The Analysis of thermal buckling of circular plates of variable thickness from functionally graded materials
mehrdad
jabbarzadeh
مدیر گروه مکانیک دانشگاه آزاد اسلامی واحد مشهد
author
جعفر
اسکندری جم
هیئت علمی دانشگاه صنعتی مالک اشتر تهران
author
mahmood
khosravi
مدرس دانشگاه آزاد اسلامی واحد نیشابور
author
text
article
2012
per
In this paper, the thermal buckling behavior of circular plates with variable thicknesses made of bimorph functionally graded materials, under uniform thermal loading circumstances, considering the firstorder shear deformation plate theory and also assumptions of von Karman has been studied. The material characteristics are symmetric to the middle surface of the plate and, based on the power law, vary along with thickness; where the middle surface is intended pure metal, and the sides are pure ceramic. In order to determine the distribution of prebuckling force in the radial direction, the membrane equation is solved using the shooting method. And the stability equations are solved numerically, with the help of pseudospectral method by choosing Chebyshev functions as basic functions. The numerical results in clamped and simply supported boundary conditions and the linear and parabolic thickness variations are presented. And the influence of various parameters like volume fraction index, the thickness profile and side ratio on the buckling behavior of these plates has been evaluated.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
59
73
http://mme.modares.ac.ir/article_1522_d46f1eff3160bb313b6e9afa56f7c9b8.pdf
Investigating Output Characteristics in Powder Mixed Electrical Discharge Machining of γ–TiAl Intermetallic
Behzad
Jabbaripour
Tarbiat Modares University
author
محمد حسین
صادقی
دانشگاه تربیت مدرس
author
محمد رضا
شبگرد
دانشگاه تبریز
author
حسین
فرجی
دانشگاه تبریز
author
text
article
2012
per
γ–TiAl intermetallic has outstanding properties such as high resistance against fatigue, oxidation, corrosion, creep, dynamic vibration and high working temperature. These intermetallics are applied in aerospace and automotive industry, turbojet engines and blade manufacturing. In this paper, powder mixed electrical discharge machining (PMEDM) of γ–TiAl intermetallic by means of different kinds of powders including Al, SiC, Gr, Cr and Fe is investigated to compare the output characteristics of the process such as surface roughness, tool wear rate, material removal rate and surface topography with each other. This is an experimental investigation, by means of die sinking EDM machine and a special tank for machining. The results indicate that, aluminum powder as the most appropriate kind of powder in the optimum particle concentration of 2 g/l, improves the surface roughness about 32% comparing with conventional EDM, decreases the tool wear rate about 19%, but decreases the material removal rate about 7.5% and also the Al powder leads to improving the machined surface topography and decreasing the surface defects and micro cracks.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
74
86
http://mme.modares.ac.ir/article_1523_c7c51480d83bb87eaad2d8d79a767d29.pdf
Nonlinear Vibration Analysis of Functionally Graded Beam on WinklerPasternak Foundation under Mechanical and Thermal Loading Via Homotopy Analysis Method
حسین
رفیعی پور
دانشگاه صنعتی شیراز
author
امیر
لطف آور
هیات علمی دانشگاه صنعتی شیراز
author
صغری
حمزه شلمزاری
دانشگاه صنعتی شیراز
author
text
article
2012
per
In this paper, the homotopy analysis method is used to nonlinear free vibration analysis of a mechanical and thermal loaded functionally graded beam on nonlinear elastic foundation. At first, the governing partial differential equation of the problem has been derived based on the EulerBernoulli theory and the VonKarman straindisplacement relationship. Then, it was reduced to a nonlinear ordinary differential equation via the Galerkin method. The homotopy analysis method which has high accuracy was implemented in order to obtain a closed form solution and study the problem parametrically. The accuracy of the proposed method is verified by those available in literatures. The numerical results demonstrate that proposed method yields a very rapid convergence of the solution as well as low computational effort. Finally, the effects of different parameters such as amplitude, linear and nonlinear elastic foundation, thermal and mechanical loads and boundary conditions were investigated on the beam vibration and their results are presented for future work.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
87
101
http://mme.modares.ac.ir/article_1524_335f7c81743cf144d633721b4a8d82c7.pdf
Theoretical, Analytical and Experimental Analysis Of Torsional Vibration On the Vehicle Crankshaft
seyed jalal aldin
seyedalian
Azad university
author
said
mahjob moghadas
Assistant Professor Imam Hosein University
author
text
article
2012
per
Automotive crankshafts are subjected to fluctuating torques due to periodic strokes in the cylinder. The gasforces and inertialforces due to the reciprocating masses will contribute to the excitation forces on the crankshaft system. The forces cause alternative torque on the crankshaft and cause vibration on the motor which cause noise and shake in the vehicle. Therefore, it’s necessary that was determined crankshaft dynamic behaviour. Although most physical structures are continuous, their behaviour can usually be represented by a discrete parameter model. In this paper, torsional vibration was determined with theoretical, analytical and experimental analysis on the Peugeot and Renault vehicle. For Solution of theoretical analysis, was used of B.I.C.E.R.A formula [1] and natural frequency for analytical analysis obtained with ANSYS software. Then, theoretical and analytical procedure compared with the experimental model, to obtain optimization model and with the best model, influence of torsional vibration was determined on the engine speed.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
102
111
http://mme.modares.ac.ir/article_1525_2f0ed08e6b23eace783f941cdd334db1.pdf
Numerical Analysis of Mechanical and Thermal Stress in Thin Cylindrical Tube under Internal Gaseous Detonation
ehsan
sheibani
دانشگاه تربیت مدرس
author
Majid
Mirzaei
associated professor of Aerospace engineerng at Tarbiat Modares university
author
text
article
2012
per
Abstract Gaseous detonation in tubes produces moving pressurethermal waves. A gaseous detonation consists of a shock wave and a reaction zone that are tightly coupled. The speed, pressure, and temperature of the products of detonation depend on the type and amount of the initial mixture. The maximum pressure of mechanical wave caused by detonation can be as high as 2030 times the ambient pressure and temperature of gas in detonation may exceed 2000°C. The mechanical shock waves can cause oscillating strains in the tube wall, which can be several times higher than the equivalent static strains. On the other hand, the passage of the heat wave produces thermal stresses in the tube wall. In the current study the resulting mechanical and thermal stresses have been assessed using numerical simulations. In practice, the mechanical and thermal displacements have been computed separately. Finally, the combined effects of mechanical and thermal stresses caused by gaseous detonation have been simulated.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
112
121
http://mme.modares.ac.ir/article_1526_0a1518eba9f6acb334b3a2f96d1026e2.pdf
Numerical and Experimental Study on the Effects of Expansion Ratio, Corner Fillets and Strain Rate in Warm Hydroforming of Aluminum Tubes
S.M.H.
Seyedkashi
Tarbiat Modares University
author
حسن
مسلمی نایینی
دانشگاه تربیت مدرس
author
غلامحسین
لیاقت
استاد/دانشگاه تربیت مدرس
author
محمود
موسوی مشهدی
استاد/دانشگاه تهران
author
Young Hoon
Moon
Professor/Pusan National University
author
text
article
2012
per
Due to the strict emission standards and fuel consumption restrictions, automotive industry is greatly interested in warm tube hydroforming of aluminum and magnesium alloys. The main shortcoming of these alloys is their inferior formability at room temperature, which can be improved by forming at temperatures below the crystallization temperature. Because of the complex nature of forming at high temperatures, the proper determination and control of forming parameters are very important in fulfillment of the process. In this paper, the effects of tube geometry, bulge height, corner fillets and strain rate are investigated on optimal internal pressure and axial feeding loading paths, which are required for successful hydroforming of annealed AA6061 tubes at 300 °C. A new method based on simulated annealing algorithm is developed for optimization of pressure and feed loading paths. Numerical results are discussed, verified and validated by experiments. A good agreement is observed between numerical and experimental results.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
122
131
http://mme.modares.ac.ir/article_1527_9c394bf136c45ce7ebd0c392e6a46565.pdf
Experimental Investigation of Geometric and Electrical Characteristics by measurements of the induced flow velocity
seyyed arash
seyyed shams taleghani
پژوهشگاه هوافضاعضو هیئت علمی
author
عبداله
شادآرام
دانشیار دانشگاه صنعتی خواجه نصیر
author
مسعود
میرزایی
دانشیار دانشگاه صنعتی خواجه نصیر
author
text
article
2012
per
This paper deals with experimental measurements of the instantaneous ionic wind velocity induced by Dielectric barrier discharge (DBD) plasma actuator in quiescent air at atmospheric pressure. A parametric study has been performed in order to increase the velocity of the ionic wind induced by the DBD actuators. The electrical and mechanical characteristics of the plasma actuator have been studied under different conditions. The main objective of this work was to help to optimize the geometrical and electrical parameters to obtain more effective ionic wind for flow control. The time averaged velocity profiles of the ionic wind show that the position of the maximum velocity come near the surface by increasing the excitation frequency. Our results indicate that the DBD plasma actuators generate vortices at the same frequency of the excitation frequency of the applied high voltage. The power, of the vortices that are shed from the actuators, increases by increasing duty cycle percentage. Unlike other similar works in this field, this study has examined the behavior of unsteady plasma actuator.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
132
145
http://mme.modares.ac.ir/article_1528_2b801d5097b1d0210d94a6ca6b7a842b.pdf
Using perturbation method to obtain scaled numerical model for analyzing noise of supercavitation
نوروز
محمد نوری
هیئت علمی (دانشیار)/دانشگاه علم و صنعت ایران
author
محمد
ریاحی
هیئت علمی (دانشیار)/ دانشگاه علم وصنعت ایران
author
ali
valipour chahardah cherik
دانشجوی دکتری/دانشگاه علم وصنعت ایران
author
text
article
2012
per
Cavitation is changing liquid phase to gas phase due to decreasing local pressure of flow induced by increasing local velocity. In situation of maximum velocity, some bubbles that contain air and vapor are produced and traveled from point of high pressure to lower pressure, so bubbles are destroyed rapidly and produce acoustic noise. Providing sufficient numerical model for simulation of acoustic waves induced by cavitation or supercavitation is so important for monitoring and controlling of these phenomena. For analyzing propagation of acoustic waves in fluid, sound is part of fluid dynamics, so momentum, energy and mass conservation equations like fluid dynamics are basics equation for identification of supercavitation. In this paper, to provide a numerical model contains hydrodynamic and acoustic parts of fluid dynamics, first by using scaled analysis, non dimensional forms of conservation equations are generated. Then by using perturbation method and considering acoustic term as a term in lower order than hydrodynamic term, conservation equations can be separated to two group equations with different orders. Leading order is hydrodynamic equations and first order is acoustic form of conservation equations. Results in first order equation show coupling of acoustic terms with hydrodynamic terms of fluid flow.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
146
153
http://mme.modares.ac.ir/article_1529_97862170f754ce2f44f2623bd1f22d2b.pdf
Application of wavelet transform in damage identification in a thick steel beam based on ultrasonic guided wave propagation
Seyed Abdorahim
Atashipour
Graduate student, Department of mechanical engineering, Isfahan University Technology
author
Hamid Reza
Mirdamadi
Assistant professor, Department of mechanical engineering, Isfahan University of Technology
author
Rasoul
Amirfattahi
Assistant professor, Department of electrical and computer engineering, Isfahan University of Technology
author
Saeed
ZiaeiRad
Professor, Department of mechanical engineering, Isfahan University of Technology
author
text
article
2012
per
In this study, the structural health of a thick steel beam, made of ST52, is inspected by ultrasonic guided wave propagation method using piezoelectric wafer active sensors that is one of the most important techniques of online structural health monitoring. The key parameters of the diagnostic waveform such as excitation frequency and cycle number are determined in relation to beam dimensions as well as pulseecho configuration of PZT active sensors attached to the beam. Finite element simulations were conducted to characterize wave propagation in the beam, and the signals of wave propagation were experimentally measured. For signal processing and feature extraction, continuous wavelet transform and scaled average wavelet power technique are used. Using the extracted features, probable existing damage in the structure is detected, localized, and intensified. The acquired results are representing a higher precision of the implemented method for damage identification and characterization with respect to a previous study.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
12
v.
5
no.
2012
154
164
http://mme.modares.ac.ir/article_1530_e924ecc4cbf78a658289847d4a363b5c.pdf