دوره 13، شماره 15 فوق العاده، اسفند 1392
text
article
2014
per

Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
0
0
http://mme.modares.ac.ir/article_10763_de8d07b7f0c8dcb3b53512bcfaf0801f.pdf
An analytic solution of transversal vibrations and frequency response of quantic nonlinear beam
محمود
پورجمشیدیان
دانشجو
author
جواد
شیخی
دانشجو
author
سعید
محجوب مقدس
دانشیار دانشگاه جامع امام حسین (ع)
author
مصیب
نوروزی نیا
دانشجو
author
text
article
2014
per
Nonlinear vibrations analysis of beams has its own specific importance in industrial, building and civil engineering applications. To achieve a propr design, the understanding of transverse vibrations of double end jointed beams and their nature frequencies, are very useful. In this paper the transverse vibrations analysis of beams with influence of constant axial load are investigated.the effects of midplane stretching and nonlinear damping terms in two case of primary and secondary resonance are also addressed. Multiple time scales method is used to make this contribution. In order to verify the accuracy of this method, the results are compared with the results of four order RungeKutta numerical method, which has a good accuracy. Comparison of this method and the homotopy method shoes that the convergence of this method is faster than the homotopy method.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
1
9
http://mme.modares.ac.ir/article_10624_de61f82234a0ce3c5409fd5bed1ed44b.pdf
Numerical Investigation of Two Simultaneous Fires in a Tunnel and Evaluation of the Obstructive Influence of Vehicles by Large Eddy Simulation
Maryam
Mapar
دانشگاه تربیت مدرس
author
Ghassem
Heidarinejad
Tehran, Ale Ahmad Ave, Tarbiat Modares University, Department of Mechanical Engineering, Room 309
author
Hadi
Pasdarshahri
دانشگاه تربیت مدرس
author
text
article
2014
per
In this paper a simulation of two fires in a tunnel in which varied arrangements of different sized vehicles at the upstream of fires has been accomplished using FDS. The results reveal that the behavior of two fires is directly influenced by distance between them. The calculated critical velocity is not affected by the variations on the small vehicles arrangement and distance between the vehicles and fires. Interestingly, the presence of medium vehicles leads ventilation flow to strengthen inertial force rather than buoyant force of fire plume in tunnel. Accordingly, when there is a short distance between fires and obstructions, less air ventilation is needed to prevent smoke backlayering. Eventually, far distance between the vehicles and the fires results in vanishing obstruction effects. Consequently, the critical velocity is the same as the case in which there is no vehicle in the tunnel.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
10
22
http://mme.modares.ac.ir/article_10625_333c0f84448dfddb7eab99c1c9f93889.pdf
A robust method for remote control of industrial plants
بهروز
رحمانی
استادیار گروه مکانیک دانشگاه یاسوج
author
text
article
2014
per
A robust delayed plantinput mapping methodology is proposed to control of industrial plants through wireless communication networks. In this way, firstly a robust classic controller is designed for original continuoustime system according to a predefined uncertainty bound. Then compensation of the destabilizing effects of a constant delay is then concerned. For this purpose, a digital controller is designed using DK iteration method. Finally this algorithm is modified to overcome the wireless network effects, e.g. random network delay, packet loss and packet disordering. Simulation studies on two benchmark industrial problems demonstrate the effectiveness of the proposed method for uncertain plants.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
23
37
http://mme.modares.ac.ir/article_10626_c1948139528c7fac806c69400d2d153a.pdf
Fuel concentration impedance simulation of a planar Solid Oxide Fuel Cell
میلاد
فدایی
کارشناس ارشد خولجه نصیر
author
lمجید
قاسمی
هیات علمی دانشگاه خواجه نصیر
author
رفعت
محمدی
دانشجوی دکتری دانشگاه خواجه نصیر
author
text
article
2014
per
This paper presents a transient model for planar solid oxide fuel cells anode, which allows the simulation of steadystate performance characteristics, transient operation behavior, as well as electrochemical impedance spectra. The developed model couples the mass transport with electrochemical kinetics. The 1D NavierStokes conservation equations and species conservation equations are used for gas transport in the anode channel, and the linear kinetic is used for the anode electrochemistry. In order to model the electrochemical impedance, a sinusoidal excitation is imposed to system of transient equations and the obtained harmonic response is used as a base for electrochemical impedance spectra simulation. In order to solve the system of the nonlinear equations, a numerical code based on finite volume method is developed and utilized. Results show that the mass transfer in channel leads to a low frequency capacitive semicircle in the Nyquist plot. Moreover, the influence of parameters such as overvoltage, temperature, velocity and hydrogen inlet concentration on the electrochemical impedance has also been studied and the results are discussed. The simulation results are in good agreement with published data.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
38
49
http://mme.modares.ac.ir/article_10627_b88ea7957e69e7e9752e3580e95bacf7.pdf
Investigation of hardness and compression behavior of Al/Short glassf nanocomposite produced by ball milling and hot pressing
علی
شکوه فر
دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Amin
Azimi
دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Ashkan
Zolriasatein
دانشگاه صنعتی خواجه نصیرالدین طوسی
author
AliAsghar
jafari
دانشگاه صنعتی خواجه نصیر الدین طوسی
author
text
article
2014
per
Nanostructured (Al8wt%Zn3wt%Mg) alloy was synthesized by simultaneous fracture and cold welding mechanisms in mechanical alloying with initial elemental powders and subsequently, this alloy was applied as matrix to fabricate Al/Short glass fiber nanocomposite in 1, 3 and 5 percent of glass fibers. The resulting powders were consolidated under 400 MPa at 380 °C in cylindrical die to produce consolidated nanocomposites. Relative density of samples reduced with increasing the percentage of glass fibers and this trend was more intense from 3 to 5 percent. Also compressive strength and hardness were investigated for these samples in different percent of glass fiber. The results showed that strength and hardness were enhanced with increasing glass fiber but decrease of mechanical properties was observed in 5 percent due to reducing in relative density. Compressive strength was compared between nanocomposite with pure Al and Al alloy matrix, and results show more reinforcement in Al based sample.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
50
58
http://mme.modares.ac.ir/article_10628_728c2a0ef392400f0bb6ffa1d293c81f.pdf
Calculation of dynamic stress intensity factors in orthotropic media under thermal loading by XFEM
محمدباقر
نظری
دانشگاه شاهرود
author
محمد
جعفری
دانشگاه شاهرود
author
مجتبی
حاجی محمدی
دانشگاه شاهرود
author
text
article
2014
per
In this paper, the eXtended Finite Element Method is implemented to model the effect of the mechanical and thermal shocks on a cracked 2D orthotropic media. The uncoupled thermoelasticity equations are considered. Isoparametric fournode and eightnode rectangular elements are used to discrete governing equations. The dynamical stress intensity factors are computed by the interaction integral method. The Newmark and the Crank–Nicolson time integration schemes are used to numerical solve the spatialdiscretized elastodynamic and thermal equations, respectively. A MATLAB code is developed to carry out all stages of the calculations from mesh generation to postprocessing. Several elastic and thermoelastic numerical examples are implemented, to check the accuracy of the results and to investigate the effect of the orthotropic direction on the stress intensity factors.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
59
69
http://mme.modares.ac.ir/article_10629_e256ba17250c2177ae5f50bbb71f4f94.pdf
High velocity penetration analysis of eroding projectile into semiinfinite concrete target
ali
Alavi Nia
دانشگاه بوعلی سینا همدان
author
mogtaba
zolfaghari
اراک
author
hossein
khodarahmi
دانشیار دانشگاه امام حسین (ع)
author
mahmood
nili
دانشیار مهندسی عمران، دانشگاه بوعلی¬سینا، همدان
author
amir hossin
ghorbankhani
دانشجوی کارشناسی¬ارشد مهندسی سازه، دانشگاه بوعلی سینا، همدان
author
text
article
2014
per
In this paper, the behavior of concrete subjected to eroding penetration of projectiles is studied. Based on qualitative similarities of eroding penetration at metallic and concrete targets, plastic flow of the particles around the projectile tip in a concrete target is illustrated. Based on viscoplastic behavior of concrete, changes on the plastic field of the target at WalkerAnderson model is made in order to analyze eroding penetration into concrete. Since there is not any analytical model and standard tests for eroding long rod (9≤L/d≤11 and 11gr<m<9gr) penetration into the concrete, 52 high velocity penetration tests were designed and carried out. Furthermore, with solving the final equations of the Forrestal model, penetration depth of eroding projectiles is calculated. Comparison between the results of the improved WalkerAnderson model and the Forrestal model showed that although the Forrestal model is a comprehensive model in rigid penetration, using it for assessment of eroding penetration into concrete is completely wrong. Besides, the improved WalkerAnderson model can analyze this phenomenon satisfactorily.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
70
82
http://mme.modares.ac.ir/article_10630_cc22833a1bdadf27e10fbecd4fbba859.pdf
Simulation of parallel electroosmotic flows with lattice Boltzmann method
Omid
Mohammadipoor
PhD student  Ferdowsi University of Mashhad
author
حمید
نیازمند
دانشیار گروه مکانیک/ دانشگاه فردوسی مشهد
author
Seyed Ali
Mirbozorgi
استادیار دانشگاه بیرجند
author
text
article
2014
per
In the present work a new lattice Boltzmann (LB) framework has been developed to study the electroosmotic flows in a 2D flat microchannel. The governing equations are presented in the continuum model, while a set of equivalent equations in LB model is introduced and solved numerically. In particular, the Poisson and the Nernst–Planck (NP) equations are solved by two new lattice evolution methods. In the analysis of electroosmotic flows, when the convective effects are not negligible or the Electric Double Layers (EDLs) have overlap, the NP equations must be employed to determine the ionic distribution throughout the microchannel. The results of these new models have been validated by available analytical and numerical results. The new framework has also been used to examine the electroosmotic flows in single and parallel heterogeneous microchannels.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
83
97
http://mme.modares.ac.ir/article_10631_8a486d9c4758451a4a02d387baac3bca.pdf
Experimental Investigation of the Vortex Structure on a Submersible Model
Ali
Saeidi nezhad
PhD Student, Mech. Eng., Yazd Univ., Yazd, Iran
author
Ali Akbar
Dehghan
Assoc. Prof., Mech. Eng., Yazd Univ., Yazd, Iran
author
Mojtaba
Dehghan Manshadi
Assis. Prof., Mech. Eng., Malek Ashtar Univ., Esfahan, Iran.
author
Mohamad
Kazemi Esfeh
MSc. Mech. Eng., Yazd Univ., Yazd, Iran
author
text
article
2014
per
The flow field around the axisymmetric streamlined bodies which forms the main body of the airplanes and submarines has been the subject of several researches. The present study aimed to investigate the flow field around a standard submersible model in various angles of attack by employing two visualization methods. The vortex structures around the model are qualitatively studied at the 40degree angle of attack in a vertical wind tunnel. These structures are visualized by the laser sheet illumination of the smoke injected flow. The shear stress field lines on the model surface in the 0≤ α ≤35° angles of attack became visible by oil and pigments. Noteworthy and distinct aspect of the present study is the application of two empirical visualizing methods which made three dimensional vortical field more understandable. Formation and development of the primary and secondary vortex along the model length are qualitatively interpreted by the results of the smoke and laser light visualization technique. Moreover, the primary and secondary separation lines along model length for various angles of attack were deduced from the results of the oil flow visualization.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
98
109
http://mme.modares.ac.ir/article_10632_84c31cdce83ab464c49b9f4e4537830e.pdf
Effects of Evaporator’s Length on Pulsating Heat Pipes’ Thermal Performance
شهاب
حقایق
دانشجوی کارشناسی ارشد دانشکده مهندسی مکانیک دانشگاه صنعتی شریف
author
محمد حسن
سعیدی
معاون آموزشی دانشگاه صنعتی شریف
author
حسین
افشین
استادیار دانشکده مهندسی مکانیک دانشگاه صنعتی شریف
author
محمد بهشاد
شفیعی
دانشیار دانشکده مهندسی مکانیک دانشگاه صنعتی شریف
author
علی
ادیب نیا
دانشجوی کارشناسی دانشکده مهندسی مکانیک دانشگاه صنعتی شریف
author
text
article
2014
per
Developing the high performance electrical devices requires high capacity heat transfer manners, which could be the pulsating heat pipes (PHPs). PHPs have a better performance in compare with conventional heat pipes (HPs), besides, they can be used to improve cooling systems for electrical devices, in future. There are some other applications for PHPs in other industries as heat transfer converters, either. The effect of the evaporator’s length on the PHPs’ performance is investigated experimentally by hiring a five turns PHPs and ferrofluid as setup and working nanofluid, respectively. The results show that PHPs’ performance is enhanced by increasing the evaporator’s length.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
110
115
http://mme.modares.ac.ir/article_10633_e35904bc12fd488106435e4047a57ae8.pdf
Jump Phenomenon and Flutter Analysis of Nonlinear Airfoil with Stochastic Approach
Saeid
Irani
Faculty/ K.N. Toosi University of technology
author
Saeid
Sazesh
Khaje Nasir Toosi University of Technology
author
Mahdi
Shayanmehr
Khaje Nasir Toosi University of Technology
author
text
article
2014
per
In this study a new approach for investigating the flutter speed of nonlinear aeroelastic systems is proposed. In this approach, the compatibility of nonlinear random vibration analysis based on the statistical properties of response is used and extended to the nonlinear aeroelastic systems to analyze the instability of these systems with using neither time domain analysis nor limit cycle oscillations. To this aim a 2degree nonlinear airfoil with cubic torsional spring under quasi steady flow is considered as an aeroelastic system. At first, one random Gaussian white noise is added to the aerodynamic lift force then the statistical linearization and the random vibration analysis of the nonlinear systems are used to obtain a nonlinear map of responsevariance with flow velocity as the control parameter. This nonlinear map leads to a nonlinear algebraic equation which consists of two parameters as the flow velocity and variance of the response. By solving this nonlinear equation for various flow velocities, the flutter speed is considered as the maximum of responsevariance. Finally the jump phenomenon is also investigated where tangent bifurcation occurs.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
116
125
http://mme.modares.ac.ir/article_10634_139d528c3fe31f1472dafe6c6dc4454f.pdf
Effect of overlapping ratio and rapid cooling in friction stir process on the microstructure and mechanical properties of AZ31 alloy
ali
alavi nia
دانشیار مهندسی مکانیک، دانشگاه بوعلی سینا، همدان
author
hamid
omidvar
 استادیار دانشکده معدن و متالورژی، دانشگاه امیرکبیر، تهران
author
hassan
nourbakhsh
دانشجوی دکترای مهندسی مکانیک، دانشگاه بوعلی سینا، همدان
author
text
article
2014
per
Friction stir process is one of the severe plastic deformation techniques which causes microstructure refinement and hence change in mechanical properties of the specimen. Temperature, strain and strain rate which are the results of this process, causing dynamic recrystallization and followed by shift in mechanical properties. Magnesium is the lightest structural alloy which is used in a wide range, in the automobile and aerospace industries. In this research, the overlapping friction stir process is applied on the surface of AZ31 alloy. The overlapping is conducted in 50 and 0 percentages. In order to reduce the temperature which is generated in the process, rapid cooling was used. After friction stir processing in the 0 percent overlapping the grains refine from 18 micrometer in the base metal to 7 micrometer with a uniformer structure than the base metal, ultimate tensile strength and elongation increased 29.9% and 19.8%, respectively with respect to the base metal. The structural uniformity of 50 percent overlapping was less than that of 0 percent overlapping, ultimate tensile strength and elongation increased 19.98% and 3.9%, respectively with respect to the base metal.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
126
135
http://mme.modares.ac.ir/article_10635_551b34da2370cca09a6c2c2d808adfcd.pdf
Thermo physical Investigation of contact between water drop and liquid methane
ali
jahanggiri
دانشجوی دکترای مهندسی مکانیک، دانشگاه سمنان
author
mojtaba
biglari
استادیار مهندسی مکانیک، دانشگاه سمنان
author
text
article
2014
per
Marine transportation is the most conventional method for transportation of natural gas, mostly liquid form; namely, Liquefied Natural Gas (LNG) to international far market. Hereon provide safe transportation of natural gas is very important. In the event of exterior material contact to LNG, swift boiling and exploding anticipated. The paper, investigates thermo physical water contact (0oC as a fluid with higher temperature) with liquid methane (cause the similarity of thermo physical properties to LNG) at low temperature (162oC). The intensity of heat transfer between water particle and liquefied methane resulted to swift pressure increase in vapor film. It causes the generation and swift growth of methane vapor film which has been resulted from abrupt evaporation and results to liquid methane explosion. In this situation, the intense vapor explosion phenomena, endangers the safety of system. Mathematical model of these phenomena has been developed by assuming saturation condition on interface phase. Then, the effects of different thermo physical parameter changes on vapor film growth have been investigated. Based on the results, in some cases, the vapor pressure pulse created in the film has been more than 3 times the initial pressure, which can endanger the safety of system.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
136
146
http://mme.modares.ac.ir/article_10636_946d0b9840c6e33f1229383d3b4ca56f.pdf
Numerical and Experimental Study on Sensitivity of Static Force Sensor Using Giant Magnetostrictive Material
shahed
mirzamohammadi
دانشجوی دکترای مهندسی مکانیک، دانشگاه شهید رجایی، تهران
author
mojtaba
ghodsi
استادیار مهندسی مکانیک، دانشگاه تربیت مدرس
author
y
hojjat
دانشیار مهندسی مکانیک، دانشگاه تربیت مدرس
author
soheil
talebian
دانشجوی دکترای مهندسی مکانیک، دانشگاه تربیت مدرس
author
text
article
2014
per
In this article, the influences of different effective parameters on sensitivity of a magnetostrictive force sensor are investigated and then, a high sensitive magnetostrictive force sensor is designed and fabricated. Initially, the operational principles related to magnetostrictive force sensors are presented. Then, conceptual design of the sensor is illustrated and sensors geometry and applied materials are determined. In the next step, measurement of magnetic hysteresis and optimization of the magnetic properties through heat treatment are presented. To this end, magnetic hysteresis curves of notannealed low carbon iron and annealed low carbon iron under different currents and magnetic hysteresis curve of bulk TERFENOLD under different preloads and currents are obtained. Then, through numerical simulations using finite element method software, parameters affecting sensor sensitivity were identified and designed. Finally magnetostrictive force sensor is fabricated and its sensitivity and functional specifications are tested under different conditions. The magnetostrictive force sensor sensitivity and linearity error are found as 0.51mV/N and 2.8% FSO respectively, which is a higher value compared to similar magnetostrictive force sensors.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
147
158
http://mme.modares.ac.ir/article_10639_24a0e2d5f3531dcb5d02b0116de7f294.pdf
Two Objective Optimization of Heat Transfer Rate and Total Cost Decrement in ShellandTube Heat Exchangers
Mohsen
Amini
K. N. Toosi University of Technology
author
majid
bazargan
دانشگاه خواجه نصیر
author
text
article
2014
per
In this research, optimization of shellandtube heat exchangers with dual objectives of achieving upper heat transfer rate and lower total cost has been done by the Genetic algorithm. All geometrical constraints and standards, minimum and maximum velocity limits as well as maximum allowable pressure drops are considered in optimization process. Relations between the objective functions and optimization variables have many complexities so that the gradient approach employed by many optimization algorithms may not be adequate. Special care has been taken in employing Genetic algorithm to assure that the optimized values of variables are not trapped in local optimum domains. To evaluate the precision of computer code of current study, a comprehensive case study has been considered. The optimization has been accomplished by considering 11 variables. In a next attempt the mass flow of cooling fluid, which is the sea water in the case under study, has been added as the 12th variable. The obtained Pareto plots show that the optimized parameters suggested by this study provide upper heat transfer rate and simultaneous lower total cost relative to available results.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
159
168
http://mme.modares.ac.ir/article_10641_2971de28ac8e74b9ef22d24c572b632b.pdf
Study of Residual Tensile Strength in Drilled Composite Laminates by Acoustic Emission
Navid
Zarif Karimi
Amirkabir University of Technology
author
hossin
heidary
دانشگاه آزاد اسلامی واحد تهران شرق
author
mahdi
ahmadi najafabadi
دانشگاه صنعتی امیرکبیر
author
a
rahimi
دانشگاه صنعتی امیرکبیر
author
mehdi
farajpur
دانشگاه آزاد اسلامی واحد تهران شرق
author
text
article
2014
per
Drilling of composite materials is one of the major processes in the manufacturing and assembly of subcomponent. However, drilling of composite laminates can cause several damages such as degradation in residual tensile strength. In this study, effects of cutting speed, feed rate and drill angle on residual tensile strength of drilled laminates has been investigated. For this purpose, the Taguchi method was employed for three factors at three levels. Acoustic emission signals and wavelet analysis are used to monitor residual tensile strength. The experimental results indicated that the feed rate has the most significant effect. Based on timefrequency analysis of AE signals, it was found that AE signals with frequency ranges of (62.5125), (250312.5) and (312.5375) KHz were generated from matrix cracking, fiber slipping and fiber breakage respectively.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
169
183
http://mme.modares.ac.ir/article_10642_ee59f5c8e3c5ed3fd72d2dd13f1a1638.pdf
Experimental Investigation of Heat Transfer Enhancement using EHD in Internal Natural Convection
Pourya
Alamdari
فارغ از تحصیل
author
ali akbar
rajabi
هیت علمی دانشگاه صنعتی اصفهان
author
mojtaba
mirhosseini
دانشجو
author
text
article
2014
per
Electrohydrodynamic (EHD) is one of the techniques for heat transfer enhancement. In current study, the enhancement of natural convection heat transfer inside a vertical tube is experimentally investigated under applying a strong electrical field (EHD). For this purpose, a wire electrode with positive polarity is used along the pipe axis while the inner surface of tube is connected to the ground. EHD disturbs the thermal boundary layer by generating ionic wind which flows from wire electrode to inner side of tube and causes the heat transfer enhancement. In this study, the effects of wire electrode diameter and also electrical field on heat transfer enhancement are investigated. Obtained data are reported as local Nusselt number along the pipe axis and mean Nusselt number. The results show that decreasing the wire electrode diameter increases the heat transfer of tube. In addition, increasing of electrical current due to strong electrical field, increases the Nusselt number. At the lowest wire electrode diameter, the highest Nusselt number was observed which was 2.03 times more than the case that no electrical field was applied.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
184
195
http://mme.modares.ac.ir/article_10643_4c29711c0e3dd71094b35f2f3bd29a4c.pdf
Elastic wave propagation in composites with random distribution of spherical inclusions using Dynamic Generalized SelfConsistent Model
کامران
دانشجو
استاد/دانشکده مهندسی مکانیک/دانشگاه علم و صنعت ایران
author
محمد
رحیم زاده
دانشجوی دکتری/دانشکده مهندسی مکانیک/دانشگاه علم و صنعت ایران
author
text
article
2014
per
The work is dedicated to the elastic wave propagation in particulate composite with random distribution of soft and stiff inclusions. The multiple scattering theory of WatermanTruell in combination of static generalized selfconsistent model is used to formulate the Dynamic Generalized SelfConsistent Model which is used because of its precision in modeling of high volume fraction and high frequency waves. The model has been described and two different cases containing of soft and stiff inclusions are considered. The propagation behavior such as normalized wave propagation, normalized attenuation and the dynamic effective properties are studied. Investigation is carried on long and intermediate wavelength regime and different values of volume fraction for longitudinal (P) and shear (S) elastic waves. The results indicate that the propagation properties are strongly affected by aforementioned parameters.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
196
206
http://mme.modares.ac.ir/article_10644_e45b921d18e44f6a684bc5bee7bff0d2.pdf
Thermoeconomic modeling and analysis of a combined fuel cell and micro gas turbine power plant cycle
jamasb
pirkandi
عضو هیات علمیدانشگاه صنعتی مالک اشتر
author
majid
Ghassemi
Prof. of Mech. Eng., K.N. Toosi Univ. of Technology, Tehran, Iran
author
text
article
2014
per
The purpose of this study is thermoeconomic analysis of a combined fuel cell and micro gas turbine power plant cycle for using in small scale CHP systems. Since the fuel cell is the main source of power generation in hybrid systems, in this study, complete electrochemical, thermal and thermodynamic calculations are performed to obtain more accurate results; and unlike most studies, the cell temperature is not assumed constant. The performance analysis of the hybrid system shows that increasing the pressure and air to fuel ratio, causes to loss of electrical efficiency and increase in the electricity price because of reduction in cell and turbine inlet gas temperatures. The other results of this study show that considering the economic life of the system, making use of this type of hybrid systems is economical and generates less electricity price in comparison with micro gas turbine.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
207
222
http://mme.modares.ac.ir/article_10645_c96ac9628bcaf372e539932ee4bc6bb1.pdf
Nonlinear free vibration of a single layered nanoplate based on the nonlocal elasticity
علیرضا
شوشتری
استادیار دانشگاه بوعلی سینا همدان دانشکده مهندسی
author
داریوش
داستانی مبارکه
دانشگاه بوعلی سینا
author
text
article
2014
per
In this paper, nonlinear free vibration of a Nano plates rectangular has been investigated. For this purpose, first, the equations of motion for Nano plate which is considered as a continuous system have been derived using Hamilton principle based on classical plate theory. Then, by definition an stress function and using Galerkin method the equations converted to an ordinary nonlinear equation and a compatible equations. Using multiple time scale method this equation has been solved and analytical relations for first nonlinear natural frequency and nonlinear mode shaped have been derived. Then for example, these relations have been studied for Graphen sheet in Armchair and Zigzag structure and the effect of aspect ratio and nonlocal elasticity parameter on natural frequency have been investigated.
Modares Mechanical Engineering
Tarbiat Modares University
10275940
13
v.
شماره 15 فوق العاده
no.
2014
223
236
http://mme.modares.ac.ir/article_10646_b615fbfba1db4e458d214c44a4e7bac3.pdf