Cover
text
article
2015
per
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
http://mme.modares.ac.ir/article_12662_a2eb21ddbb164f8af9a5875af526f726.pdf
IFC
text
article
2015
per
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
0
0
http://mme.modares.ac.ir/article_12660_f9b28b6f944c790f5a747f10f9eac5af.pdf
Content
text
article
2015
per
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
0
0
http://mme.modares.ac.ir/article_12661_44557e85dfb57a5e8d82b4ff76331c43.pdf
Multi-objective robust active acoustic radiation control of a piezocomposite arbitrary thick rectangular panel
Hemad
Keshavarzpour
Iran University of Science and Technology
author
Seyyed Mohammad
Hasheminejad
دانشگاه علم و صنعت ایران
author
text
article
2015
per
Active structural acoustic radiation control of a piezolaminated arbitrary thick rectangular plate with a mixed-norm H_2/H_∞ robust controller is developed. The structure is made of a transversely isotropic host layer with a distributed piezoelectric sensor layer as well as a matched piezoelectric actuator layer, facing high frequency uncertainties and random external disturbances. The elasto-acoustic formulation, based on the exact linear 3D piezo-elasticity theory, is developed for problem of fully coupled structure and acoustic mediums. Identification of the fluid/structure interaction system with subspace algorithm is implemented on actuator/sensor data sets. A multi-objective controller with regional pole placement, formulated in LMI framework, is synthesized while unmodeled dynamics are treated as multiplicative uncertainties. Numerical simulations confirm effectiveness of the implemented multi-objective robust active control scheme for reduction of radiated acoustic power from a piezocomposite plate, without stimulating any instability. Also, better tracking performance and disturbance rejection of mixed-norm controller is observed in comparison to that of H_2 and H_∞ controllers. Finally, validity of the elasto-acoustic model is proved by results obtained from a finite element software, as well as with the data available in the literature.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
1
12
http://mme.modares.ac.ir/article_12240_a8db67a4cabb55f06be162a429dcf13e.pdf
Numerical Investigation of Emulsion Process in Microchannels, Using Index-Function Lattice Boltzmann Method
Morteza
Alizadeh
Student
author
Mohammad
Taeibi Rahni
Professor
author
Mohammad
Eftekhari Yazdi
استادیار دانشگاه
author
text
article
2015
per
Emulsion consists of drops of one liquid dispersed into another immiscible liquid, is a novel technique for producing monodisperse droplets. The aim of this research is using the Lattice Boltzmann Method (LBM) to simulate two-phase flows in micro-channels to access the emulsification process. To this approach, The Index-Function Model proposed by He, is used to simulate drop formation in emulsification process in a co-flowing micro-channel with a complex geometry and three inlets. The simulation is performed to investigate the mechanism of drop generation due to dripping and jetting modes and the mode between them. Index function model, which is a new reliable model to evaluate two-phase flows, is applied to track the motion and deformation of the interface between the two immiscible fluids. Accuracy of our results is examined by two well-known basic analytical models including Relaxation of a rectangular drop and coalescence of two static droplets. Our results indicate good agreements with analytical data. The dimensionless numbers such as Capillary and Velocity ratio were used. The Capillary number is one of the most important dimensionless numbers in determination of fluid flow characteristics in micro-channels. The simulations reproduce dripping, widening jetting and narrowing jetting simultaneously in a coflowing microchannel in agreement with the experimental ones. This indicates that index function LBM model has a good accuracy and high stability to simulate this kind of flow.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
13
22
http://mme.modares.ac.ir/article_12235_a4d88bb3f28479419efbc58378e10223.pdf
Optimization of angled-rib turbulator geometry in order to enhance the thermo-hydraulic behavior of the flow using Taguchi method
Alireza
Zamani Aghaie
دانشجوی دکترا / دانشگاه فردوسی مشهد
author
Asghar
Baradaran Rahimi
استاد دانشگاه فردوسی مشهد
author
Alireza
Akbarzadeh
استاد / دانشگاه فردوسی مشهد
author
text
article
2015
per
In this paper, thermo-hydraulic behavior of a solar heater is numerically investigated and optimum geometry for the angled-rib turbulator which produces the maximum thermal enhancement factor is determined by Taguchi method. A general innovative geometry is introduced for the rib, that changing in its geometrical parameters will lead to three convenient types of turbulators, namely triangular, rectangular and trapezoidal ribs, simultaneously. َApplying Taguchi method leads to the optimum geometry parameters. A L16 (44) orthogonal Taguchi array is used. The aim of the Taguchi analysis is maximizing the thermal enhancement factor. The factors employed for the analysis are rib relative pitch, height, tip width and percentage of upstream-side perpendicularity. The analysis has been carried out for a flow of Re=10000 and a constant rib width. Due to the twofold effect of turbulators on thermo-hydraulic behavior, thermal enhancement factor concept is employed which stands for both heat transfer rate and friction factor. Results show that rib pitch and height have the most effect on thermal enhancement factor, respectively. The optimum rib geometry is found to be a triangular rib which has P/H=2, e/H=0.2 and 100% perpendicularity.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
23
29
http://mme.modares.ac.ir/article_12236_e7cec0b289024e36cd12f101468c0893.pdf
Experimental and numerical study of friction in free bulging
304 stainless steel seamed tube using elastic pad
Hasan
Ghaforian Nosrati
دانشجوی کارشناسی ارشد/دانشکده مهندسی مکانیک دانشگاه شاهرود
author
Mahdi
Gerdooei
Shahrood University/Assistant Professor
author
text
article
2015
per
In recent years, rubber pad forming process have many advantages, such as high flexibility, good surface quality and lower manufacturing costs; RPF have been widely used in automotive, aerospace and military industries. In present research, numerical and experimental analysis of free bulging 304 stainless steel seamed tube, using a polyurethane elastic pad has been studied. Firstly, 3D simulation of seamed tube bulging using the finite element ABAQUS/Explicit 6.12 software by several frictional conditions has been performed. An incompressible hyperelastic pad has been modeled by Mooney-Rivlin constitutive equation and the elastic-plastic behavior as more as progressive ductile damage criterion FLD for steel tube were assumed. In the experimental activity, compression test of rubber was carried out according to ASTM D575-91 standard and compressive stress-strain curve and the Mooney-Rivlin constants were determined. Forming of meshed tubes by using elastic pad with different lubricating systems have been conducted up to onset of bursting in the seam weld and longitudinal, hoop and thickness strains were measured. Results showed that friction, especially between rubber and tube plays the main role in controlling wrinkles, increasing the bulge depth, reducing the forming load and friction dissipation energy of the process. Also observed that the intact parts without any wrinkles formed by using nylon lubricant between tube and rubber and drawing oil between tubes and die.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
30
40
http://mme.modares.ac.ir/article_12237_4f80bd5ed76578f8d031ca34af9214f3.pdf
Modeling elastohydrodynamic lubrication of cam and flat follower mechanism with grease via Multi-grid method
Amir
Torabi
دانشکده مهندسی مکانیک
دانشگاه صنعتی اصفهان
author
Saleh
Akbarzadeh
استادیار دانشگاه صنعتی اصفهان
author
Mohammadreza
Salimpour
دانشکده مهندسی مکانیک
دانشگاه صنعتی اصفهان
author
text
article
2015
per
One of the challenging problems of tribology is cam and follower elastohydrodynamic lubrication due to the simultaneous effect of various lubrication mechanisms. These mechanisms are transient, squeeze film, elastic deformation of contacting surfaces and variation of lubricant properties with pressure. In this paper, besides studying the mentioned factors, the effect of using a non-Newtonian lubricant such as grease is numerically investigated. The lubrication governing equations and Oswald’s grease behavior equation have been discretized using finite difference technique. The system of equation has been solved via Multi-Grid method which is an advanced iterative method in solving system of partial differential equations. The results are showed for Newtonian oil comparing to grease for different cam rotational speed. Also different grease behaviors are investigated. The results are verified by a comparison to the results obtained using the famous Newton-Raphson method. Finding shows that the minimum lubricant thickness as well as the maximum pressures is lower when using grease compared to the case that a Newtonian lubricant is used. In the case of Newtonian lubricant, increasing the speed results in an increase in the lubricant film thickness but it is shown that the speed does not affect the lubricant thickness in the case of non-Newtonian lubricant.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
41
50
http://mme.modares.ac.ir/article_12238_4d73bc59b71081cab44919bc1bc0cc9e.pdf
Experimental investigation on core shape effect on compressive properties of sandwich structures with composite skins, corrugated composite core and foam
Abbasali
Mohammadi Dehabadi
MSc/Tarbiat modares university
author
G. H.
Rahimi
Tarbiat Modarres Univ
author
Rahmatollah
Rahmani
MSc/Tarbiat modares univercity
author
text
article
2015
per
In this paper, the behavior of sandwich structures with composite skins and the core that consists of foam and a corrugated composite laminate under compressive load is investigated experimentally. Three geometrical shapes including square, trapezoid and triangle forms are considered for corrugated composite laminate and results are compared with reference specimen with simple core that is made of foam. Skins and corrugated composite laminate are made from woven glass and epoxy resin; and PVC foam is used in core. Corrugated composite laminate are built using the hand layup method and vacuum assisted resin transfer molding technique is used to join the skins to the core. In order to experimental accuracy of test; three same samples have been product for each type of core shapes and the average of data’s test have been used for comparing the results. The edgewise compressive test based on ASTM is used to perform the experimental test. The results show that set corrugated laminate composite in core improves the mechanical properties (such as compressive strength, axial stiffness, toughness) and the ratio of mechanical properties to weight of these structures to a large extent, Also by approaching to square shape the structure have more favorable properties. The results have shown that compressive strength is increased from 188.56% (triangle core) to 362.37% (square core) and the ratio of compressive strength to weight is increased from 92.36% (triangle core) to 141.4% (square core).
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
51
57
http://mme.modares.ac.ir/article_12239_6423370ba6da000788053df140488534.pdf
Robot-Borne PLC-Based Control System Used for Lower Limbs Rehabilitation
Mohammad Hosein
Kardan
Department of Mechatronics Engineering, Kashan Branch, Islamic Azad University, Kashan, Iran
author
Mohsen
Irani Rahaghi
Asisstant Professor, Department of Solid Mechanics, Faculty of Mechanical Engineering, University of Kashan, Kashan, Iran
author
text
article
2015
per
The purpose of this study, control and monitoring of a rehabilitation robot with two degrees of freedom (2-DOF) for rehabilitation of the lower limbs of patients with loss of ability for movement due to injury, disease, stroke or surgical operations. After determining the movements, that is included flexion-extension movements of the knee and hip joints, the performance of the mechanism was investigated using dynamic analysis and simulation. Then, a programmable logic controller (PLC) was employed to control the robot performance. Finally, the accuracy of PLC program was guaranteed by monitoring the robot. Passive, assistive and resistive exercises were considered in programming the controller. In assistive exercises, the forces needed by the patient to perform the movements were actually set automatically by using the feedback data provided by the patient's forces. In addition, to perform the resistive exercises rather than using actual weights, negative loads were employed. The results obtained represent considerable accuracy to perform the movements and create safe conditions for the patient. Also, high flexibility in programming has provided the possibility to perform a wide range of rehabilitation exercises.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
58
66
http://mme.modares.ac.ir/article_12241_93af1e62dec24db4883d8a804449e8dc.pdf
Modeling Gas Liquid Cylindrical Cyclone Separator and Optimizing Effective Geometry Parameters
Amirhosein
Ghasemi
K.N.Toosi University of Technology
author
Mehrzad
Shams
دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Mohammad mahdi
Heyhat
K.N.Toosi University of Technology
author
text
article
2015
per
In this study, performance of gas liquid cylindrical cyclone separators and the effect of changing geometrical parameters of cyclone separators entrance is investigated. The cyclone is simulated with computational fluid dynamic methods. After choosing a suitable mesh grid for the cyclone and checking grid independency, the effect of changing entrance geometry on gas carry under and liquid carry over is investigated. Geometrical parameters, especially inlet geometrical parameters have great effect on optimizing cyclone separators performance. RSM model is used for turbulence simulation of the flow and two phase flow is simulated using Eulerian- Eulerian approach. In this simulation, inlet cross section, inlet angle and inlet height relative to the cyclone bottom part are optimized. Results show that GCU decreases with decreasing nozzle’s inlet angle. An optimum point for GCU was given with changing inlet altitude relative to the bottom of the cyclone and inlet nozzle’s width. An optimum point for LCO was obtained with changing inlet altitude and inlet nozzle width. Increasing inlet angle causes a decrease in LCO. In optimum model, gas carry under decreases significantly and liquid carry over is eliminated.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
67
75
http://mme.modares.ac.ir/article_12242_9301916855fce4c81d9e29a60706b83f.pdf
Analysis of Fracture Modes in Cortical bone Using Optimized Arkan’s Device
Behroz
Sepehri
عضو هیات علمی/ دانشگاه ازاد اسلامی مشهد
author
Ali
Asadi
دبیر آموزش و پرورش
author
text
article
2015
per
Human bones experience different modes of loading including tension, compression, bending, and torsion. The modes of loading depend on the activities done by the body. Regarding the crack shape and loading modes, by the time only the first mode of fracture has been studied in order to analyze the fracture toughness. However, it is necessary to analyze different modes of fracture in order to find more reliable results. In this research, finite element analysis and calculations for geometric coefficients were done to obtain the toughness of bone. Hence, first, second, and combined modes of fracture in cortical samples having cracks were studied numerically and experimentally. To this end, bovine tibia was used to make standard tensile samples for implementation in Arkan’s device. Some optimizations were made on the Arcan’s device. These were included of bone fixation in the device and ability of performing tests in different angels. Stress intensity factor (Kc) was obtained for different fracture modes. Results showed a decrease in KIc respect to change in loading angle while KIIc acted vice versa. Performing some extra optimizations, the device can be used for tortional fracture mode in a torsional test device.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
76
80
http://mme.modares.ac.ir/article_12248_e0bdb65556a310b83af284b3fd3d1bc7.pdf
Work Hardening of FCC Crystals in Crystal Plasticity Theory
Kurosh
Hasanpour
استادیار دانشگاه اصفهان
author
Ali
Shafiei
دانشجوی کارشناسی ارشد/دانشگاه اصفهان-دانشکده فنی مهندسی-گروه مهندسی مکانیک
author
text
article
2015
per
Increasing usage of metals in engineering structures has made the metal forming process become superior in the solid mechanic researches. Meanwhile, the physical theories are of high significance due to the individual features. The crystal plasticity theory is one of these theories. This theory predicts the texture evolution and deformation of these materials by modeling the plastic deformation mechanisms of crystal material’s micro-structure (such as metals). Connecting with micro-structure enables this theory to predict the anisotropy of single crystals, and also the prediction of some phenomena in polycrystals which are aggregate of single crystals, is possible. Presenting a suitable work hardening model which contains the anisotropy behaviors of single-crystals is very important. In this paper, at first, the principles of crystal plasticity are explained, and then by evaluating several experimental results and the most commonly used work hardening models, a new work hardening model will be presented. This model adapts better with experimental results, compared to the previous models. The scope of this research is specifically for crystal materials with FCC structure, nevertheless, some part of this research is applicable to the other structures.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
81
92
http://mme.modares.ac.ir/article_12247_70f6e6e87f18e40761631a6079db5a70.pdf
Experimental Investigation of Instability of a Supersonic Mixed Compression Air Intake
Mohammad Reza
Soltani
استاد دانشگاه شریف
author
Mahdi
Abedi
کارشناسی ارشد مهندسی هوافضا دانشگاه صنعتی شریف
author
Javad
Sepahi Younsi
دانشجوی دکترای تخصصی مهندسی هوافضا دانشگاه صنعتی شریف
author
text
article
2015
per
An extensive experimental study has been conducted to investigate the performance and stability of a supersonic axisymmetric mixed compression air intake. The intake has been designed for a free stream Mach number of 2.0. However, tests were conducted for free stream Mach numbers of 1.8, 2.0, and 2.2. This investigation is aimed to study effects of Mach number and back pressure on the intake flow stability during the buzz phenomenon. Further, the effect of acoustic resonance on the Buzz frequency has been investigated. Buzz phenomenon is defined as the shock oscillation ahead of the intake that may occur when the intake mass flow ratio reduces. Results show that the stability margin reduces when the free stream Mach number increases. In addition, reducing the free stream Mach number and increasing the back pressure cause the oscillation frequency to increase. The main cause of instability start is flow separation on the compression ramp and two ranges of frequency of buzz oscillations are obtained, range of 100 Hz for flow instability for Mach numbers of 1.8, 2.0 and 2.2, and range off 475 Hz for flow instability in Mach number of 1.8. For both cases, the spatial domain of buzz oscillations covers the entire intake length. Further, this low and high frequency ranges have significant conformity with the zeroth-order and first-order of the acoustic resonance frequency, respectively, that increase the probability of existence of acoustic resonance driving the buzz oscillation.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
93
100
http://mme.modares.ac.ir/article_12249_a7619378cb8396ed71d3068ed7c33039.pdf
Size-dependent pull-in instability analysis of FGM nano-beam under molecular force by differential quadrature method
Hossein
Ataei
دانشجوی کارشناسی ارشد، دانشکده فنی و مهندسی دانشگاه شهرکرد، شهرکرد
author
Yaghoub
Tadi Bani
استادیار دانشکده فنی و مهندسی دانشگاه شهرکرد
author
text
article
2015
per
In this paper, pull-in instability of a cantilever beam type nanoactuator made of the functionally graded material (FGM) based on higher order modified strain gradient theory investigated. It is assumed that the functionally graded beam, made of germanium and silicon, follows the volume fraction definition and law of mixtures, and its properties change as a power function through its thickness. By changing the germanium constituent volume fraction percent of the nano-beam, five different types of the nano-beams are investigated. The influences of the volume fraction index, length scale parameter and the intermolecular forces, on the pull-in instability are examined. Principle of minimum total potential energy used to derive the nonlinear governing differential equation and consistent boundary conditions which is then solved using the differential quadrature method (DQM). The present analysis is validated through direct comparisons with published other research methods and experimental results and after comparison excellent agreement has been achieved between new solution method and other experimental and numerical solution results. Besides, the results demonstrate that size effect and amount of volume fraction have a substantial impact on the pull-in instability behavior of beam-type nanoactuator.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
101
111
http://mme.modares.ac.ir/article_12250_c5cfa2b9b4506d38bbc6fa480dabd63f.pdf
Numerical simulation of spray characteristics of bio-ethanol and its blend with gasoline in a direct injection combustion chamber
MohammadMehdi
Naghizadeh
Graduate student of school of mechanical engineering
author
Amirreza
Ghahremani
دانشجوی مکانیک دکتری دانشگاه صنعتی شریف
author
Mohammad Hassan
Saidi
استاد دانشگاه صنعتی شریف
author
text
article
2015
per
In this study, spray behavior of bio-ethanol as a regenerative fuel that reduces emissions such as NOX and CO is investigated in a combustion chamber and compared to its different blends with gasoline. For this purpose, microscopic and macroscopic spray characteristics and also evaporated fuel mass after the injection are modeled and investigated using Fire 2013. It is concluded by increasing bio-ethanol content in the fuel, evaporated fuel mass, spray cone angle, spray area and sauter mean diameter increases, however spray tip penetration remains roughly constant. Increase of injection pressure, decreases spray cone angle and suater mean diameter and increases evaporated fuel mass, spray area and spray tip penetration. If the energy content and time of injection of bio-ethanol and gasoline be equivalent the results vary significantly compared to previous cases. In this case bio-ethanol has a longer spray tip penetration and spray area, higher fuel mass evaporated and smaller spray cone angle and sauter mean diameter compared to gasoline. The increased spray tip penetration and spray area in this case may lead to piston impingement and bore wetting resulting increased hydrocarbon emissions and decreasing engine efficiency.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
112
122
http://mme.modares.ac.ir/article_12281_bf0adcb8d9ded01138687f36c80c084c.pdf
Evaluation of dynamic mode-III stress intensity factors of multiple cracks in an elastic half-plane
Hamed
Haghiri
دانشجوی کارشناسی ارشد، طراحی کاربردی، دانشگاه یزد، یزد
author
Ali Reza
Fotuhi
استادیار گروه مهندسی مکانیک، دانشکده فنی و مهندسی، دانشگاه یزد
author
Alireza
Shafiei
مهندسی مکانیک، دانشگاه یزد، یزد
author
text
article
2015
per
In a structural analysis, dynamic response of a crack is of significant importance as well as the impacts of elastic waves on stress intensity factors (SIF). In this paper, dynamic analyses of multiple cracks on a half-plane subjected to anti-plane shear stresses are presented. Stress intensity factors are calculated and the interaction of elastic waves with the boundary of plane and the cracks' tips is investigated at different locations. The distribution discontinuous displacement techniques are used, enabling us to solve the crack problems in dynamic fracture mechanics. Integral transformations (Laplace and Fourier) are applied to elastodynamics equations and by using a set of appropriate boundary conditions solved discontinuous displacement and the crack problem is solved through discontinuous displacement method. As a result, the stress equations with hypersingularity terms are obtained. Using Chebyshev series expansion and collocation points in Laplace domain, the crack solution is achieved. Finally, different algorithms of numerical Laplace inversion are presented and the stress intensity factors (SIF) are obtained. The presented results are compared with published data and a good agreement is observed. Moreover, it is also demonstrated that the present theoretical study is capable of modelling multiple cracks with different arrangements.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
123
132
http://mme.modares.ac.ir/article_12277_b9ee723f5ee851244ad95d6f6c16ad7f.pdf
Investigation of continuous cooling transformation behavior of API X70 gas and oil pipeline steel
Mostafa
Nakhaei
دانشگاه بیرجند
author
Sayyed Hojat
Hashemi
University of Birjand
author
text
article
2015
per
The API X70 steel is a high-strength low alloy steel which is used in construction of high-pressure long-distance gas and oil transportation pipelines with large-diameter. The pipe used in this study has 1422mm outside diameter and 19.8mm wall thickness, formed by spiral welding. As this steel is totally imported from abroad, the study of continues cooling transformation behavior and the optimum design of thermo-mechanical control processes are important for its domestic production. In this study, dilatometry examination was conducted on API X70 steel in a wide range of cooling rates from 0.5 to 40 °C/s. The optical microscopy observation and microhardness measurement were used to verify the observed microstructures. From the experimental results, the continuous cooling transformation curves (CCT) were constructed for API X70 pipeline steel. Different microstructures including granular bainite, pearlite, acicular ferrite and bainitic ferrite were observed depending on the cooling rate of tested samples. The observed dominant microstructure in 5 and 7.5 °C/s cooling rate was acicular ferrite which is the desired microstructure in energy transportation pipeline steels. These results can be used to design the optimum thermo-mechanical control process (through the selection of proper cooling rate) in domestic manufacturing of the API X70 steel.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
133
140
http://mme.modares.ac.ir/article_12278_3520a4312432f880a127112382cf6708.pdf
Modeling of 2D Two-Phase Flow in Cascade Blades of Steam Turbine Using Jameson’s Finite Volume Method with CUSP Technique
Mohammad Reza
Mahpeykar
Professor- FUM
author
Edris
Yousefi Rad
دانشگاه فردوسی مشهد
author
text
article
2015
per
Dry Steam flow at blade passages of steam turbines' low pressure stages occurs due to rapid expansion, delay in condensation and the condition of supercooled dry steam and finally after nucleation and condensation shock, phase change from vapor to liquid droplets occurs which is called two-phase or wet steam flow. In this paper, the aim of developing finite-volume flow of wet Jameson is considered for the first time in two-dimensional study by using the advantages of CUSP's numerical method. In this paper, equations governing the formation of liquid phase are combined with equations of survival and by using CUSP's numerical approach in Jameson's finite-volume method (the integrated method) the positive features of both of these methods can be simultaneously used in the modeling of two-phase flow. To calculate nucleation, the classical equation of nucleation with appropriate correction and also Lagrangian solution for growth of droplets are used in integrated method. Additionally, condensation shock effect on the pressure distribution and the droplet size has been calculated and compared with experimental data. Given the importance of areas of shocks on the suction surface of the blade, the focus of integrated method is shifted to this area. The results of integrated two-phase model are examined in subsonic and supersonic flow output .In the shock area on suction surface blade, using the CUSP's method (the integrated method) shows a better coverage in predicting attributes of flow in target area in comparison with the experimental data by a reduction of 20 percent in numerical errors.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
141
150
http://mme.modares.ac.ir/article_12280_7cc0087309ba0427689aafa4c0ea49b3.pdf
Analysis of the effective parameters on mass transfer in brain capillaries using lattice Boltzmann method
Mina
Alafzadeh
دانشگاه صنعتی اصفهان
author
Ebrahim
Shirani
استاد-موسسه آموزش عالی صنعتی فولاد
author
Effat
Yahaghi
دانشگاه بین المللی امام قزوین
author
Mehdi
Rahmani
دانشگاه صنعتی اصفهان
author
Nasser
Fatouraee
دانشگاه صنعتی امیرکبیر
author
text
article
2015
per
Neurological diseases such as cancer, damage blood brain barrier and consequently cause more permeability in tissues. In general if there is damage to the brain tissues, the contrast agent used in MRI, diffuses outside the capillaries and the MRI picture brightness changes. The purpose of this paper is to show the effects of different parameters on the contrast agent diffusion in the brain capillary. In this study, the lattice Boltzmann method with multi-relaxation time (MRT) is used to simulate the flow in the capillary and porous media around it. The results show that the porosity in extravascular tissues (it shows the tissue damage), the kind of contrast agent and capillaries curvature have impact on the contrast agent diffusion in the tissues. The presented results show the effects of curvature on shear stress and thus on mass transfer in the capillary. It should be noted that the presented results have been evaluated by previous statistical and analytical results for flow in the damaged brain capillary with different permeability. It has been shown that the lattice Boltzmann method is able to simulate the complex problems especially in porous media.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
151
158
http://mme.modares.ac.ir/article_12279_0e9946f8234c4c9a4c0f5084a0953ca6.pdf
An investigation of Forming through using the new method of ball deep drawing and comparing its thickness distribution and forming force with the conventional deep drawing
Abdolhamid
Gorji
استادیار دانشگاه صنعتی نوشیروانی بابل
author
Esmaeil
Mohammadian
Graduate student
author
Mohammad Ali
Mirzai
Faculty member
author
text
article
2015
per
Forming media in metal forming processes is so important. Since the forming media in Ball deep-drawing process is discrete, it is quite flexible. In this paper, thickness distribution and required force for forming of conical part by ball deep-drawing and conventional deep-drawing processes using finite element simulation and experimental stages, were studied. In this research, sheets were used made St14 steel and brass wit 1mm thickness. The experimental results are in good agreement with simulation results. The results showed the sample formed by conventional deep-drawing process had more uniform thickness distribution than ball deep-drawing, but the maximum thinning in the parts of ball forming process was less than conventional deep-drawing process. Also it was observed that required force for ball deep drawing process is more than the conventional deep-drawing process. It was observed that with increasing radius of the input die, the force required to stretch the ball deep-drawing and ball processes is decreased, also with increasing radius of the input die is reduced thinning amount. It was noted that one of the advantages of ball deep drawing process than traditional deep drawing process is achieved a negative slope part.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
159
166
http://mme.modares.ac.ir/article_12282_b71835034068fc181981b94e3f30bb3a.pdf
Analytical study of cross stream diffusion for combined electroosmotic and Poiseuille flows in rectangular microchannels: inclusion of EDL effect
Milad
Reshadi
M.Sc. Student of Mechanical Engineering, Sharif University of Technology
author
Mohammad Hassan
Saidi
Professor, School of Mechanical engineering, Sharif University of Technology
author
text
article
2015
per
Dissemination of an analyte under the laminar flows plays a major role in measuring and assessment of biological fluids such as sample preparation in the context of microfluidic systems. Due to the development of manufacturing technology in the Lab-on-a-chip devices, the production of rectangular microchannels with finite aspect ratios and micron and submicron sizes has been provided by which the effect of electrokinetic phenomena on concentration distribution will be magnified in these systems. Since the recent researches in this field have overlooked such effects, the present work will be conducted analytically to study the effect of electric double layer on cross stream diffusion of the analyte in the combined electroosmotic and pressure driven flows. Three flow scenarios, the favorable, adverse and zero pressure gradients are analyzed. The results demonstrate that the width of the diffusion region near the top and bottom walls of the microchannel becomes broader with the increase in the Debye length. Also, the results of the scaling analysis reveal the decrease in mixing intensity with increasing the Péclet number based on Helmholtz-Smoluchowski velocity and dimensionless Debye–Hückel parameter. As well, the average scaling exponent of this criterion is a descending function with respect to the thickness of the electric double layer.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
167
176
http://mme.modares.ac.ir/article_12283_0361de8b964420ab55da400bd3225fd1.pdf
Experimental and Numerical Study of Effective Parameters in Forming of Double-Stepped Parts and Optimization of the Initial Blank Shape
Reza
Mousavipoor
Master student of mechanical engineering
author
Abdolhamid
Gorji
استادیار دانشگاه صنعتی نوشیروانی بابل
author
Mohammad
Bakhshi
Professor of mechanical department
author
Ghorban
Mohamad Alinejad
lecture of mechanical department
author
text
article
2015
per
Production of double-stepped metal sheet parts is considered as a complex and difficult task in industries. The crankcase is such a complex double-stepped part for the automobile industry, which its production with traditional methods is associated with many problems. In this paper, the formability of this stepped part has been studied experimentally and by simulation using hydrodynamic deep-drawing with radial pressure. It is shown that the crankcase can be formed successfully in one step by the hydroforming process. Moreover, the effect of fluid pressure on the thickness distribution and die filling and the effect of geometric parameters such as punch corner radius and the height of the steps on the thinning, and also optimal shape design of the original blank were investigated. The study showed that choosing the correct forming pressure can improve formability and increase the amount of die filling. It is also illustrated that by increasing the punch corner radius, the maximum thinning is reduced and the thickness distribution is improved and by increasing the height of the steps, thinning in the wall of the first step and the punch corner radius increase and by decreasing the height of the steps, thinning position will be shifted toward the second step. Also, by optimizing the original blank, it has been concluded that the optimization of the shape of original blank has a major impact on the material flow and will delay the sheet rupture.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
177
187
http://mme.modares.ac.ir/article_12284_68ee14e498ba975632756ba0b3d6b00c.pdf
Numerical investigation of drag coefficients in 2D parachute-like bodies with permeability assumption
Faezeh
Rasi
استادیار-پژوهشگاه هوا فضای وزارت علوم، تحقیقات و فناوری
author
Iman
Laraibi
کارشناسی ارشد مهندسی فضایی-
کارشناس پژوهشی پژوهشکده سامانه های فضانوردی
author
text
article
2015
per
In current study, for a special fabric that is used for parachute canopies; the permeability of the canopy has been estimated empirically and numerically. Moreover, the coefficients of Darcy's equation resulted from experiment, used in 2D numerical simulation of a single parachute-like body. Assuming permeability for the fabric, the drag coefficient was showed a 39 percent decrease rather than solid canopy. Comparison between solid canopy and permeable one, showed significant differences in the results, especially in streamlines and pressure distribution. In order to diminish the numerical effort, the canopies were taken as 2D hemi-spherical porous cups. So-called two dimensional numerical simulations using FLUENT® software was conducted on a group of paired permeable with two different diameters in various vertical and horizontal distances. The diameter of lower canopy was considered as half of the upper one. Tandem canopies use in order to reduce the inflation shock of main parachute. The lateral relative displacement of lower canopy to upper one has been considered in order to stimulate true descending conditions. The results showed the interaction between flow fields of canopies has strong effect on drag coefficient of the cluster parachutes. Therefore, determining the length of the risers as the vertical distance and relative diameter of parachutes and their interactions found to have tremendous effect in designing cluster parachutes. The study showed that the most desirable longitudinal distance between two canopies was equal to the diameter of lower canopy.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
188
194
http://mme.modares.ac.ir/article_12286_bec9fb71c630846cc815a44dc5078dde.pdf
Experimental and numerical investigation on the effect of dimple on heat exchanger performance and louver effectiveness in multilouvered fin banks
Hossein
Shokouhmand
Faculty of Mechanical engineering, Tehran University
author
Farhad
Sangtarash
Faculty of Mechanical Engineering, University of Tehran.
author
text
article
2015
per
Numerical and experimental models have been developed to investigate the effect of implementing in-line and staggered arrangement of dimple on heat transfer augmentation and pressure drop of the air flow through a multilouvered fin bank. Three-dimensional simulations of single row of louvers have been conducted for aforementioned geometry. Simulations are performed for different Reynolds number. The simulation revealed that heat transfer and temperature augmentations occur due to existence of a circulation region created by dimple. Additionally, continuous temperature gradients have been observed over the louver surface with the highest temperature at the base of the louver and the lowest temperature at the middle of the louver. Besides, the difference between these two points is more obvious in higher Reynolds numbers, especially in the first louvers. Fin efficiency and fin effectiveness have been calculated to assess the louver performance. The air-side performance of heat exchanger is evaluated by calculating Colburn j factor and Fanning friction f factor. Results show that implementing dimples on the louver surface increase j factor and f factor. The present results indicated the staggered arrangement, in comparison with in-line arrangement, could effectively enhance the heat transfer performance. The results show that both fin bank performance and louver effectiveness will be increased against an acceptable increase in pressure drop.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
195
202
http://mme.modares.ac.ir/article_12285_9c13c99331879c458f065975487e432e.pdf
Investigation of Mixing in Electroosmotic Micromixers using Nernst-Planck Equations
Jafar
Jamaati
Department of Mechanical Engineering, Razi University
author
Ali Reza
Farahinia
Department of Mechanical Engineering, Ferdowsi University of Mashhad
author
Hamid
Niazmand
Department of Mechanical Engineering, Ferdowsi University of Mashhad
author
text
article
2015
per
Mixing within electrokinetic micromixers is studied numerically in this article. Micromixer studied here is simply a heterogeneous parallel plate microchannel which is imposed to the electroosmotic flow field. For the through modeling of such flows, the coupled equations of Navier-Stokes, Nernst-Planck, Poisson-Boltzmann and concentration equations are solved for the flow motion, electric charges transport, electric field and species concentrations, respectively. Numerical solution of these set of equations for the heterogeneous microchannels is complicated and difficult. Therefore, simple and approximate model such as Helmholtz-Smoluchowski has been proposed which is basically appropriate for the case of microchannels with the homogenous properties on the walls. Validation of Helmholtz-Smoluchowski model is well-examined for the prediction of two dimensional flow fields, yet its applications is rarely validated for the prediction of concentration field and mixing performance. In this article mixing due to electroosmotic flow field is investigated using Nernst-Planck equations as well as Helmholtz-Smoluchowski models and the accuracy of the Helmholtz-Smoluchowski model is evaluated. Comparison of the results indicates that for the proper conditions, approximate model can predict the mixing performance accurately along the micromixer length.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
203
213
http://mme.modares.ac.ir/article_12287_42175ccc039df86a483264bbc0fb4392.pdf
Distributed control of nonlinear Burger’s equation
Behrooz
Rahmani
استادیار گروه مکانیک دانشگاه یاسوج
author
Amin
Moosaie
هیات علمی
author
Ahmad
Mansourian Tabaei
دانشجو
author
text
article
2015
per
In this paper, a method for distributed control of nonlinear Burger’s equation is proposed. In this method, first the nonlinear partial differential equation governing the system is transformed into two linear partial differential equations using the Takagi-Sugeno linearization; such that their fuzzy composition exactly recovers the original nonlinear equation. This is done to alleviate the aliasing phenomenon occuring in nonlinear equations. Then, each of the two linear equations is converted to a set of ordinary differential equations using the fast Fourier transform (FFT). Thus, the combination of Takagi-Sugeno method and FFT technique leads to two ordinary differential equation for each grid point. For the stabilization of the dynamics of each grid point, the use is made of the parallel distributed compensation method. The stability of the proposed control method is proved using the second Lyapunov theorem for fuzzy systems. In order to solve the nonlinear burger equation, a combination of FFT and finite difference methodologies is implemented for the . Simulation studies show the performance of the proposed method, for example the smaller settling time and overshoot and relatively robustness with respect to the measurement noises.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
214
220
http://mme.modares.ac.ir/article_12373_36034dcf9ce24f0c62e7c708bf1ec43f.pdf
Investigating the geometrical parameters of nozzle-mix burners form the combustion exergy points of view using Taguchi method
Hamideh
Sheikhani
دانشجوی دکترای تخصصی / دانشکده پردیس، دانشگاه فردوسی مشهد
author
Mohsen
Ghazikhani
عضو هیات علمی / دانشگاه فردوسی مشهد
author
Hosein
Ajam
عضو هیئت علمی/ دانشگاه فردوسی مشهد
author
text
article
2015
per
Nozzles branching, fuel injection angle and nozzle diameter can affect the mixing process and combustion performance of nozzle-mix burners. In the current work, CFD approach and Taguchi method are employed to investigate the effects of these parameters on the irreversibility of combustion process. Combustion in nozzle-mix burner is first simulated by use of CFD method. The governing equations, including continuity, momentum, energy and chemical reactions are solved numerically by use of FLUENT. Standard k-ε and EDC models are used for modeling turbulence and interaction between chemical reactions and turbulence, respectively. Then, the developed model is experimentally investigated and numerical method is validated. Using the Taguchi method, the effects of each parameters, their priority and optimum values are determined by use of Minitab. A L9(33) orthogonal Taguchi array is used with the analysis aim of minimizing irreversibility. Results show that injection angle, number of branches and nozzle diameter have the most influence on the combustion irreversibility, respectively. The optimum configuration of the nozzle-mix burner is determined to have a 45º injection angle, 4 branches and 4mm nozzle diameter. The corresponding irreversibly to this optimum case is 45.88%.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
221
228
http://mme.modares.ac.ir/article_12288_904c332bb77ca58ee98bf41bd6149c40.pdf
Experimental investigation of energy absorption behavior by an aluminum profile with special cross-section subjected to the quasi-static lateral loading
Abbas
Niknejad
Assistant Professor
author
Mojtaba
Firouzi
نویسنده دوم
author
Hamid Reza
Saadat Fard
نویسنده سوم
author
text
article
2015
per
This article investigates energy absorption capacity and plastic deformation of lateral flattening process on an aluminum profile with special cross-section under the lateral compressive loading in the quasi-static condition by experimental method. The profile section is a circular tube with two symmetric longitudinal grooves. Different samples with various lengths and outer diameters in three different filling conditions consist of empty, core-filled and full-filled by polyurethane foam were prepared. Some specimens with the same geometry and filling condition but, with different loading angles of 0, 30, 45, 60 and 90o respect to symmetric line of two longitudinal grooves, were laterally compressed. Effects of various parameters such as profile length, outer diameter, three different filling conditions, and loading angle are investigated on lateral loading and specific absorbed energy. Experimental results show that specific absorbed energy is independent of specimen length. At the same displacement, when diameter of samples increases compressive loading decreases. Also, in zero loading angle, presence of the filler enhances lateral load; and consequently, increases specific absorbed energy by the structure. In viewpoint of the design of an energy absorber design, optimum specimen is full-filled profile under a loading angle equal to zero. However, if due to some design limitations, assembling the special profile with loading angle of zero is impossible, assembling the structure in empty condition with loading angle of 90o can be the next suggestion. Experiments show that the highest specific absorbed energy occurs in the profile with different diameters under loading angles of zero and 90o.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
229
238
http://mme.modares.ac.ir/article_12374_23c1a64e5ccdadda537102f3323f3c99.pdf
Reconstructing the damage shape in aluminum plate using guided Lamb wave and polygon reconstruction technique in Tomography
Amirashkan
Mokhtari
دانشکده مهندسی مکانیک دانشگاه صنعتی امیرکبیر
author
Abdolreza
Ohadi
author
Hamidreza
Amindavar
عضو هیات علمی / دانشکده مهندسی برق دانشگاه صنعتی امیرکبیر
author
text
article
2015
per
One of the most important challenges in the field of structural health monitoring and non-destructive testing is to assess some features of damages in structures, like the shape of damaged region. To reconstruct the shape of damage there are different methods in tomography. Already, researchers have used two general types of shape reconstruction techniques: transform based methods and algebraic reconstruction methods. Both methods suffer from some disadvantages like high sensitivity to incomplete data sets, bulky and expensive scanning hardware or low image resolution. In this work, a novel method to find the shape of damage via polygon reconstruction technique in tomography using the Radon transform is introduced. In this technique, damaged region is approximated by a polygon which the number of its sides is chosen arbitrarily, and the aim is to find this polygon’s vertices. To achieve this goal, an aluminum plate with a triangular hole as the damage was modeled in software. Then beams of guided Lamb wave were propagated toward the damaged region using arrays of piezoelectric transducers in just a few numbers of angles. Finally the polygon’s vertices were determined by processing the reflected signals from the damaged region. The results confirmed the efficiency of the proposed method.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
239
246
http://mme.modares.ac.ir/article_12375_91f10cba8f09705d52c4462fa4b2da4e.pdf
Free vibration and divergence instability of pipes conveying fluid with uncertain structural parameters
Ali Asghar
Alizadeh
Master of science student/Isfahan university of technology
author
Hamid Reza
Mirdamadi
Associate professor/ Isfahan University of Technology
author
text
article
2015
per
In this article, Monte Carlo simulation method is used in conjunction with finite elements (FEs) for probabilistic free vibration and stability analysis of pipes conveying fluid. For fluid-structure interaction, Euler-Bernoulli beam model is used for analyzing pipe structure and plug flow model for representing internal fluid flow in the pipe. By considering structural parameters of system as random fields, the governing deterministic partial differential equation (PDE) of continuous system is transformed into a stochastic PDE. The continuous random fields are discretized by mid-point and local average discretization methods; then, by Monte Carlo simulations in each iteration loop, every distributed-parameter PDE having stochastic lumped-parameters is transformed into a deterministic distributed-parameter PDE. Each PDE is transformed into a system of deterministic ordinary differential equations (ODEs) by using FEs. Accordingly, all of the deterministic and stochastic parameters of system are discretized. For free vibration analysis, the eigenvalue problem is solved for investigating the complex-valued eigenvalues and critical eigenfrequencies. Consequently, having complex eigenfrequencies and divergence points, the statistical responses of stochastic problem are obtained like expected values, standard deviations, probability density functions, and the probability of occurrence for divergence instabilities.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
247
254
http://mme.modares.ac.ir/article_12376_ea480dc2f4036ce508d2406d97c158e4.pdf
Study the effect of autofrettaging of functionally graded cylinder on the surface crack parameters using numerical discretizing of stress fields
Rahman
Seifi
استاد/دانشگاه بوعلی سینا همدان
author
AliReza
Dejam
کارشناس ارشد/ دانشگاه بوعلی ینا
author
text
article
2015
per
In this paper, the variations of the stress intensity factor and energy release rate have been investigated based on the displacement correlation and modified crack closure integral methods for external surface cracks in the autofrettaged functionally graded cylinder (FGC). Mechanical properties vary in the radial direction according to the desired function. Isotropic material behavior and bilinear elastoplastic stress-strain relationship are considered for the FGC. Autofrettage process induces the tensile residual stresses in the outer parts of the cylinder wall, which causing the undesirable effects on the external surface cracks. Many variables affect the distribution of tensile residual stresses. Effects of autofrettage ratio, volume fraction of material and cylinder thickness on the residual stress changes and addition, changes in the size and direction of surface cracks on the stress intensity factor and energy release rate are studied. The results show that the volume fraction has the greatest effects on both crack parameters. The axial cracks are critical in compared with circumferential and angled cracks. The principle of superposition can be used to determine the combinational effects of the residual stresses and applied loads on the behavior of cracks in the graded materials.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
255
264
http://mme.modares.ac.ir/article_12377_a06e5719206d5a11a6f56aed9c9e80f7.pdf
Experimental study of mill speed, charge filling, slurry concentration, and slurry filling on the wear of lifters in tumbling mills
Moslem
Mohammadi Soleymani
آدرس اول:کرمان، بلوار جمهوری، دانشکده فنی و مهندسی دانشگاه شهید باهنر، بخش مکانیک، دانشجوی دکتری. آدرس دوم: کرمان، انتهای جهاد، جنب شهرک افضلی پور، دانشگاه پیام نور کرمان، گروه فنی و مهندسی، مربی گروه مکانیک.
author
Majid
Fooladi Mahani
دانشیار، مهندسی مکانیک، دانشگاه شهید باهنر، کرمان
author
Masoud
Rezaeizadeh
استادیار، مهندسی مکانیک، دانشگاه تحصیلات تکمیلی و فناوری پیشرفته، کرمان
author
Mehdi
Bahiraie
کارشناسی ارشد، مهندسی مکانیک، دانشگاه ولی عصر، رفسنجان
author
text
article
2015
per
Milling is one of the most important operational stages in processing the minerals. Lifters are usually used with mill liners to extend their life and to enhance the grinding and crushing efficiency. Lifters worn and consequently their dimensions change during the course of operation. These changes in dimensions have a significant influence on the overall economic performance of the mills. Therefore, it is useful to know the relationship between the mill operation and the lifter profile, and the influence of lifter wear on the change in lifter profile. The wear is influenced by a range of parameters such as: media charge level, slurry filling, slurry concentration, and mill speed. In this work, the influences of these operating parameters were investigated using a pilot mill (1000 * 500 mm). To this end, a Copper ore was used to prepare slurry at 40%, 50%, 60%, 70%, and 100% solids concentration by mass. The tests covered a range of slurry filling (U) from 0.5 to 3 with solid charge between 15% and 35% of mill volume and 3 different speeds 65%, 75% and 85% of critical speed. It is found that the mill charge and the mill speed significantly affect the wear rate. For wet condition, increase in the slurry concentration and slurry filling leads to a remarkable decrease in the amount of the wear. By increase in the feed filling (in dry condition) the wear increases too. Wear rate in wet conditions is 2-4 times of dry condition.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
265
271
http://mme.modares.ac.ir/article_12378_2d209d5378ebfde9a5ad9dab2f0201bf.pdf
Investigation on mixed mode elastic-plastic fracture behavior of ABS polymeric material
Naghdali
Choupani
Sahand University of Technology
author
Morteza
Soltanpour Khamneh
دانشگاه صنعتی سهند
author
text
article
2015
per
Abstract Nowadays, polymeric materials are used in most industrial and engineering applications. In many of the applications, crack is initiated in mixed mode loading conditions. As a result, investigation of these materials at different loading angles is essential for safe design of structures. In this paper the mixed-mode elastic-plastic fracture behavior of ABS material based on J-integral key parameter was studied and the modified Arcan fixture was employed to investigate fracture behavior of this material under pure mode I (opening mode), pure mode II (shearing mode) and in plane mixed mode loading conditions. This work has been carried out experimentally by J–integral method named multi-specimen and normalization techniques. Finally, by fitting linear and power functions based on ASTM E813-81 and E813-87 test procedures respectively, the fracture toughness of this polymeric material was obtained in plane strain condition. The (J-R) curve comparison showed good agreement between the two methods. The minimum difference between the two methods obtained in a shear mode by ASTM E813-81 was about 1.37% and the maximum difference observed in tensile mode by ASTM E813-87 was about 30.7%.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
272
280
http://mme.modares.ac.ir/article_12379_3a7c3fcfdf3cecc4ffba6e07a10fbb1f.pdf
The influence of elastic property and inertial force on the length of vortices in viscoelastic fluid flow inside planar channel with the gradual expansion
Mohammad Mohsen
Shahmardan
عضو هیات علمی دانشکده مهندسی مکانیک
دانشگاه شاهرود
author
Mahmood
Norouzi
عضو هیات علمی دانشکده مهندسی مکانیک دانشگاه شاهرود
author
Hassan
Hassanzadeh
عضو هیات علمی دانشکده مهندسی مکانیک دانشگاه بیرجند
author
Amin
Shahbani
دانشجوی دکتری
author
text
article
2015
per
Due to the diversity and width applications of polymeric fluids in various industries the investigation of viscoelastic fluids is noted by many researchers. In this study, non-creep flow of viscoelastic fluid has investigated inside planar channel with gradual expansion for the expansion ratio of 1:3. The laminar and incompressible flow of viscoelastic fluid has been simulated numerically using finite volume method and PISO algorithm. The nonlinear PTT rheological model has been applied to study effect of elasticity property on the length of vortices in polymeric fluid flow. The investigation of symmetric and asymmetric vortices length in a wide range of Reynolds and Weissenberg numbers is the main purpose of present study. The three angles of 30, 45 and 60 degrees have been considered for influence of the expansion angles on the length of vortices. The study of polymeric fluids flow through the planar channel with gradual changes in cross section (with expansion angles less than 90 degrees) is the innovation of this research. Also the critical values of first and second for Reynolds and Weissenberg numbers have been expressed in various expansion angles and furthermore length of second and third vortices has been presented as a function of Reynolds and Weissenberg numbers. The length of symmetric vortices decreases with increment of elastic property at all expansion angles for values of Weissenberg numbers less than one. Whereas the growth of expansion angle leads to increase in the length of symmetric and asymmetric vortices for low Reynolds and Weissenberg numbers.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
281
291
http://mme.modares.ac.ir/article_12441_cb0275e6f4b59195d029f60ccb5a11a2.pdf
Unknown input observer for sensor fault detection in linear systems with unmatched uncertainties
Esmaeel
Bagherpour-Ardakani
دانش آموخته دکترای مهندسی مکانیک از دانشگاه تهران
author
Mohammad Reza
Hairi Yazdi
Associate Chair for Undergraduate Studies
author
Mohammad
Mahjoob
دانشیار دانشکده مهندسی مکانیک دانشگاه تهران
author
text
article
2015
per
This paper is devoted to sensor fault detection in linear systems with observer-based approach. It is assumed that the system has linear dynamics with the presence of uncertainties. The uncertainties are modeled as unknown input (disturbance), while it is assumed that the well-known observer matching condition is not necessarily satisfied. To decouple the unknown-input effects, and distinguish their effects from the fault effects, an equivalent dynamic system is proposed which is independent from the unknown input. The equivalent system is constructed by the use of a unique integral filter. The introduced integral-filter, which is called buffer-based integral filter in this paper, has frequency response similar to the low-pass filter. Hence, the capability of noise filtration will also be provided. The construction of the equivalent dynamic system is achieved from the use of multiple successive buffer-based integrators and the number of successive filters is related to relative degree between the unknown input and the sensor output. Then, an unknown input observer is proposed for the equivalent system, and therefore, a disturbance-decoupled and fault-sensitive with exponential-convergent toward-zero residual vector will be generated. Although, the generated residual vector can be used for sensor and actuator fault diagnosis problems; however, the focus of this paper will be on the sensor fault detection. Finally, the applicability of the proposed method will be investigated via simulation of a simple inverted-pendulum on a horizontal-moving cart.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
292
300
http://mme.modares.ac.ir/article_12442_4612b98909a14ddaae20f04e1b273268.pdf
Technical-economic analysis of a diesel engine fuelled with biodiesel based on experimental data
Farshad
Meisami
دانشگاه فردوسی مشهد
author
Hossein
Ajam
عضو هیئت علمی دانشگاه فردوسی مشهد
author
text
article
2015
per
Biodiesel is a renewable fuel that can be produced from vegetable or animal oil. The main benefit of using biodiesel is its capacity to lower exhaust emissions compared to diesel fuel. Over the last few years, numerous studies have been performed on biodiesel production and its effect to engine performance and emissions. However, in those studies; no attention has been paid in economic analysis of biodiesel usage in engines. In this investigation, various mixtures of biodiesel and diesel fuel have been tested on a four cylinders turbocharged diesel engine. The combustion reaction was determined by using the experimental data. Then, the mass flow rate of each exhaust emissions was calculated, using combustion reaction. The economic analysis was performed considering social cost of emissions, inlet fuel cost and the cost of engine power loss. Because of low diesel fuel price in Iran, the results were determined by ignoring the inlet fuel cost. The technical analysis was also performed considering the engine performance results. The results showed that the 10% and 15% biodiesel-diesel blends (B10 and B15) were more affordable than diesel fuel. The performance results of engine were also acceptable in these blends. The power loss was slight and the highest thermal efficiency was also observed in these blends. All biodiesel blends were more affordable than diesel in emissions economic analysis
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
301
309
http://mme.modares.ac.ir/article_12443_6a2d3bb9fb87cda082f6de00b3e494ea.pdf
Analytical investigation of dynamic stability of FGM shallow arches
Ali Asghar
Atai
استادیار دانشگاه تهران
author
Mehdi
Alizadeh
دانش آموخته کارشناسی ارشد
author
text
article
2015
per
The major concern in Shallow arches behavior under lateral loading is their instability at a critical load, which can make the structure to collapse or displace to another stable configuration, a phenomenon called snap through. By introduction of functionally graded materials in recent years, and incorporating them into this problem, interesting results can be obtained which can give structures with favorable stability properties. In this work, dynamic stability of the hinged-hinged functionally graded shallow arch under implusive loading is investigated. Material properties vary through the thickness by power law. Nonlinear governing equations are derived using Euler-Bernoulli beam assumption and equations of motion are expressed by a nonlinear differential-integral equation. The solution utilizes a Fourier form of response. The procedure of analysis of dynamic stability that is followed in this work uses the total energy of the system and the Lyapunov function in the phase space that consists of essentially three steps: First, one finds all the possible equilibrium configurations of the shallow arch. Next, the local dynamic stability of each of the equilibrium configurations is studied.. Last, when the preferred configuration from which a snap through may occur is locally stable and when there is at least one other locally stable equilibrium configuration, then we proceed to find a sufficient, condition for stability against snap through. The effect of gradation on stability and critical load of the arch is investigated in detail.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
310
320
http://mme.modares.ac.ir/article_12444_62b784a42dd6dc46cf7b9170a5679e92.pdf
Design and fabrication of a minesweeper spider robot based on the klann mechanism
Behnam
Miripour Fard
Head of Robotics Eng. Dept
author
Atefeh
Hassani
کارشناس رباتیک
author
Samaneh
Farhani
کارشناس رباتیک
author
Mohammad Javad
Najari
کارشناس رباتیک
author
text
article
2015
per
In this paper, designing and fabrication of a prototype of the spider robot is presented. The mechanical and electrical design of the robot is described and then programming and control are addressed. First, after surveying of various mechanisms for legged locomotion, the Klann mechanism has been selected for robot locomotion. The mechanical model has been build using CATIA software and simulations have been done for validation of the performance of the m. The spider-like robot has eight legs. To add the ability of mine detection to the robot, PI metal detector circuit has been designed and made. This circuit has the ability to detect metal but does not recognize the type of metal and its range is about 1 m. Tele-operation control method has been used to control the robot in which the operator can remotely (up to a radius of 300 m) control the robot using a computer. The performance of the robot can be improved using metal detectors circuit. The advantages of spider robot with Klann mechanism is easily tackling of the obstacles and maintaining the balance on uneven terrain or sandy surfaces.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
321
330
http://mme.modares.ac.ir/article_12445_aec8f68c4e2faad9974ed39fe6c14a46.pdf
Studying the effect of sound absorber materials in acoustical behavior of double-wall cylindrical shell
Anooshiravan
Farshidianfar
عضو هیات علمی/دانشگاه مشهد
author
Pouria
Oliazadeh
دانشگاه فردوسی مشهد
author
text
article
2015
per
Sound transmission through a double – wall circular cylindrical shell is investigated. In order to study the acoustic behavior of these kinds of thin circular cylindrical shells, an exact analytical approach is discussed in detail. Using an infinitely long thin walled circular cylindrical shell subjected to a plane wave incidence, the structure – acoustic equations based on the Donnell’s thin shell theory are obtained and transmission losses calculated by this approach are compared to the transmission losses obtained according to the Love’s theory. The comparison shows that the Donnell theory distinguishes all the frequencies in which sound transmitted inside the shell easily and it predicts the sound transmission characteristics of a thin circular cylindrical shell better than the Love’s theory especially in resonance – controlled and mass – controlled regions. Then the effects of different sound absorber materials and various gases are studied in order to fill the cylindrical shell’s gap with a material except air. The results show that high sound transmission loss and better trend can be achieved by using these sound absorber materials in double-wall circular cylindrical shells.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
331
338
http://mme.modares.ac.ir/article_12446_01840fd5d8d437d011722b82a460a483.pdf
Progressive Damage Investigation of Glass- Epoxy Laminated Composites under Fatigue Loading
Soran
Hassanifard
عضو هیأت علمی/دانشگاه تبریز
author
Mohsen
Feyzi
دانشگاه تبریز
author
text
article
2015
per
Composite materials are widely used in aerospace, automotiveindustry, and other fields because of special mechanical properties.In this study, a step by step numerical analysis was developed to predict the fatigue life of E-Glass/Epoxy fiber reinforced laminates with (0, 90, 0, 90) s and (90, 0, 90, 0) s configurations. In the proposed Finite Element (FE) analysis, Hashin’s failure criterion was used which can distinguish the failure modes. The iterative algorithm was utilized so thatat each step of solution, the maximum load was applied to the model and then the stress componentswere obtained numerically at every nodes of the model. Then the appropriate failure criterion was applied to inspect the possible failure in all layers of each element. For failed layer in an element, material properties were degradedaccording to the failure mode and progressive damage theories. In other elements whichhad not been failed, the damage parameter was calculated. If the value of the damage parameter in each element exceeds 0.9, the layer of the element was assumed to be failed and the algorithm was continued. The predicted fatigue life was compared with the experimental results in the literature and good agreement was observed.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
339
347
http://mme.modares.ac.ir/article_12447_5af024c46b6c14a9ea63caa38c8691de.pdf
Optimization of hybrid cooling system including direct evaporative cooler- cooling tower in order to minimize operation cost using genetic algorithm
Ghassem
Heidarinejad
Tehran, Ale Ahmad Ave, Tarbiat Modares University, Department of Mechanical Engineering, Room 309
author
Seyed Zia
Miri
دانشگاه تربیت مدرس
author
Hadi
Pasdar Shahri
دانشگاه تربیت مدرس
author
text
article
2015
per
Hybrid cooling systems is used to increase the cooling effectiveness of direct evaporative coolers. In this study, a hybrid cooling system including cooling tower, cooling coil and evaporative cooler have been discussed. The major aim of hybrid systems using is to reduce the energy consumption compare to the other cooling methods. So in this research, optimization of hybrid system was investigated. In order to have an accurate performance prediction of hybrid cooling system, a numerical simulation was performed and the results validated using experimental measurements. Moreover, genetic algorithm is used to determine the optimal design parameters. Minimizing the operation cost including water and electricity costs is considered as the objective function. All design constraints and standards were considered in optimization process. Investigated case study indicates that the optimal design can significantly reduce the operation costs. Optimization results revealed that in optimal case, air mass flow of cooling tower is lower than water mass flow. Also, the velocity of air through evaporative pad was obtained the minimum allowable value and the cross section of cooling tower was obtained the highest possible value according to the constraints. Finally, importance of water and electricity in the optimum system design was investigated due to lack of water in some areas.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
348
354
http://mme.modares.ac.ir/article_12448_7e3649ab7b5f98338608a6135efa52a7.pdf
Identification of effects of Nylon nanofibers on carbon- epoxy composite properties by Acoustic Emission
Ramin
Khamedi
استادیار عضو هیات علمی گروه مکانیک- دانشکده مهندسی- دانشگاه زنجان
author
Mohammad
Nikmehr
دانشگاه زنجان
author
text
article
2015
per
The aim of this article is to investigate the effects of Nylon nanofiber in carbon- epoxy composites properties under double cantilever beam test by Non-destructive Acoustic Emission testing. In order to increase tougher of carbon- epoxy composite, Nylon nanofibers were placed in to the midplane interface of carbon- epoxy laminates. In order to better identification of the effects of Nylon nanofibers and more accurate clustering of Acoustic emission parameters were used combining of k-means algorithm and Genetic algorithm for clustering. Acoustic emission descriptors like Amplitude, Duration, Count, Acoustic Energy and Rise time were used in order to survey identification of effects of nanofibers. The results of clustering of Acoustic emission signals that obtained from carbon- epoxy composite and carbon- epoxy nanomodified composite shows that the presence of Nylon nanofibers increase the tougher of carbon- epoxy composite and delayed damage mechanisms. This method of clustering is a good fit between acoustic signals and damage mechanisms and time of events. Cumulative events of Acoustic emission Amplitude obtained from damage mechanisms of both composite are in the same range and Acoustic emission duration of carbon-epoxy is more than carbon-epoxy nanomodified composite.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
355
360
http://mme.modares.ac.ir/article_12449_e779cb2c6f5fe75158251fe98a38a49e.pdf
Experimental Study and Analytical Modeling For Inelastic Response of Rectangular Plates Under Hydrodynamic Loads
Hashem
Babaei
استادیار دانشگاه گیلان
author
Tohid
Mirzababaie Mostofi
دانشجوی دکترا دانشگاه گیلان
author
Majid
Alitavoli
دانشیار دانشگاه گیلان
author
text
article
2015
per
The main aim of this paper is to study the inelastic deformation of fully clamped rectangular plates under hydrodynamic loading by low rate with drop-hammer, both experimentally and analytically. In the analytic section, some models are presented for predicting the mid-point deflection by two methods consisting the plastic hinge and energy method. in the plastic hinge method, it is assumed that the used plate in the experimental analysis consists a central hinge and four decentralized hinge inside and also four hinges for fully clamed supported conditions; but in the energy method, the proposed model assumes the deformation in three directions and membrane and bending strain, besides the deformation profile and also the strain rate is assumed. To do this, in experimental section, some experiments were conducted on rectangular plates with different thickness, materials and different levels of energy in order to validate the obtained results from analytic results and also surveying the mechanical behavior of materials according to impacts. By comparing analytic and experimental results, it is obvious that results have satisfying accuracy, therefore using the presented analytic models is desired for predicting the mid-point deflection of rectangular plates under the hydrodynamic loading.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
361
368
http://mme.modares.ac.ir/article_12450_5dd894ab2ba06c1cac6e7718b9a7d212.pdf
Optimized Design of LPRE Control System Hydro Mechanical Actuator Based on Open Loop Reference Model
Ali
Jafar-Gholi
KNT university
author
Hassan
Karimi
Faculty of Aerospace Engineering, K. N. Toosi University of Technology
author
Seyed Reza
Mousavi Firdeh
Amir Kabir University
author
text
article
2015
per
In this paper, a novel design approach for a hydro mechanical actuator of LPE control system is investigated. In point of admissible response rate, actuator mechanism is designed rotational. Pay special attention to the control element profile in the design of the actuator. This profile determines the conversion efficiency of the liquid propellant engine. Fitness of engine+ servomotor+ hydro mechanical actuator model to the open loop reference model is the key idea that considered as optimized design basis. Reference model would be determined based on desired dynamic behavior criteria's. With the availability of LPE mathematical model and after the design of hydro mechanical actuator, its parametric model is developed. When engine+ servomotor modeling development are completed and optimization criteria is assigned, parametric model optimization based on evaluation algorithm would be accomplished. Finally, fitness improvement between integrated and open loop reference models is evaluated. Before starting the optimized design process, the input signal and its corresponding cost function properly defined. Results shown by correction of actuator geometrical parameters and compensator gain, cost function amount – based on tracking error of liquid propellant engine combustion chamber pressure reference signal - 4 times is improved.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
369
378
http://mme.modares.ac.ir/article_12451_256db8f85b4e57ed775e19afdb33171d.pdf
Effects of friction stir welding parameters on mechanical quality of AA1100 aluminum alloy to A441 AISI steel joint
Majid
Elyasi
استادیار دانشگاه صنعتی نوشیروانی بابل
author
Hamed
Aghajani
دانشگاه آزاد اسلامی واحد ساری
author
Morteza
Hosseinzadeh
دانشگاه آزاد آیت الله آملی
author
text
article
2015
per
Friction is an important factor that causes frictional heat generated in the friction stir welding process and makes the joint between work pieces. The objective of the present work is investigate on the effects of friction stir welding parameters on the mechanical properties and material flow in AA1100 aluminum and A441AISI joint. In this study, tool offset, plunge depth, welding linear speed and tool rotational speed were chosen as variable parameters. Comprehensive analysis using the experimental results showed that the strongest joint obtained at 1.3 mm tool offset and 0.2 mm plunge depth when to the offset tool rotational speed and linear speed were 800rpm and 63mm/min respectively. Fracture locations in tensile test at all samples were in aluminum sides. Internal defects that caused in lower tool rotational speed removed by increasing the revolving and with growing trend in linear speed due to the more forging force, the surface defects abated. The maximum strength of welded joints with selected parameters was 90% aluminum base metal. In this research, microhardness of joint interface ascended with increasing rotational speed. This phenomenon is due to formation of thick intermetallic layers in abutting edges of sheets.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
379
390
http://mme.modares.ac.ir/article_12470_aff767fa7ead6e89402e457207d49004.pdf
Jacobian analysis, dynamic modeling and adaptive control of a cable robot with six degrees of freedom and six cable
Golnaz
Jafari Chogan
دانشگاه صنعتی نوشیروانی بابل
author
Mohammad Hasan
Ghasemi
دانشگاه صنعتی نوشیروانی بابل
author
Morteza
Dardel
دانشگاه صنعتی نوشیروانی بابل
author
text
article
2015
per
In this paper, adaptive control method is presented for a parallel cable with six degrees of freedom and six cable. Adaptive control method is a way for controlling systems that there is uncertainty in the parameters. The main objective of this study is tracking trajectory of a parallel cable robot which there is uncertainty in the mass of end effector and moments of inertia. Before addressing the issue of control, Jacobian matrix of robot is obtained. Then the dynamic equations of motion are derived using Lagrange method and is written in standard form. The presented adaptive control method is combination of feedback linearization method and Lyapunov stability theorem. Using feedback linearization method, control law is designed and adaptation law is planned by use of Lyapunov stability theorem. Due to the unique feature of cable suspended robots that cables can only pull the end effector, the cable tension values must be positive. In this paper, a method is used that cable tension values obtained positive for each initial condition and any desired path. Adaptive controller is designed such that unknown parameters of system is correctly estimated and system stability is guaranteed. Through several numerical simulations accuracy of kinematic, dynamic model and applied controller is shown. In order to demonstrate the effectiveness of adaptive control, the comparison between the adaptive control method and the method of feedback linearization is performed.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
391
400
http://mme.modares.ac.ir/article_12471_21399f487c70b9dac952910ffa9aabeb.pdf
Study of the hardening models in T-shape pulsating hydroforming process
Amir
Ashrafe
دانشجوی دکتری مهندسی مکانیک دانشگاه بیرجند
author
khalili
khalili
دانشیار هیات علمی- دانشگاه بیرجند
author
text
article
2015
per
In hydroforming process, the curve of internal pressure versus axial feeding is called loading path which is the key to produce a desire product. Finite element simulation of tube hydroforming can be used to study the loading path effect on the final part characteristics. In this research the finite element simulation of pulsating hydroforming process has been done in conjugation with two different work hardening models: an isotropic hardening and a mixed isotropic-nonlinear kinematic hardening model, which is capable to describe the Bauschinger effect. The parameters of both hardening models have been obtained from tensile test data. The result of the both finite element simulations were compared to experimental work. The results show that the mixed hardening model gets better prediction of final product characteristics than isotropic hardening. The differences between the results of two hardening models are from this fact that in a hydroforming process the tensile and compression loads are used and the loads reversal may be occurred. To study the effect of pulsating pressure on tube material characteristic, a three-step bulge test with unloading has been done and the results have been compared to monotonic bulge test. Loading and unloading of internal pressure cause a higher bulge height for a final pressure level compared to monotonic bulge height. The finite element simulation of pulsating hydroforming has been compared to linear hydroforming. The reported bulge heights and thicknesses show an improvement in formability of tubular material in pulsating hydroforming by considering the average pressure level which was applied.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
4
no.
2015
401
412
http://mme.modares.ac.ir/article_12472_6341c6c7ccf2450d318f1820b2f1f149.pdf