Cover
text
article
2016
per
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
0
0
http://mme.modares.ac.ir/article_13931_0035c3fc7634f0d967842c3fe226d762.pdf
IFC
text
article
2016
per
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
0
0
http://mme.modares.ac.ir/article_13930_2f0bdc029f2bc84cc4bc6f9ad2ed4f88.pdf
Content
text
article
2016
per
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
0
0
http://mme.modares.ac.ir/article_13932_c82bbe518aecc7513b11b70f9801e363.pdf
Application of Gram-Schmidt orthogonalization method in uncertainty quantification of computational fluid dynamics problems with arbitrary probability distribution functions
Saeed
Salehi
University of Tehran
author
Mehrdad
Raisee Dehkordi
دانشگاه تهران
author
text
article
2015
per
In the present paper, nondeterministic CFD has been performed using polynomial chaos expansion and Gram-Schmidt orthogonalization method. The Gram-Schmidt method has been used in the literature for constructing orthogonal basis of polynomial chaos expansion in the projection method. In the present study, for the first time the Gram-Schmidt method is used in regression method. For the purpose of code verification, the output numerical basis of code for uniform and Gaussian probability distribution functions is compared to their corresponding analytical basis. The numerical method is further validated using a classical challenging function. Comparison of numerical and analytical statistics shows that developed numerical method is able to return reliable results for statistical quantities of interest. Subsequently, the problem of stochastic heat transfer in a grooved channel was investigated. The inlet velocity, hot wall temperature and fluid conductivity were considered uncertain with arbitrary probability distribution functions. The UQ analysis was performed by coupling the UQ code with a CFD code. The validity of numerical results was evaluated using a Monte-Carlo simulation with 2000 LHS samples. Comparison of polynomial chaos expansion and Monte-Carlo simulation results reveals an acceptable agreement. In addition a sensitivity analysis was carried out using Sobol indices and sensitivity of results on each input uncertain parameter was studied.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
1
8
http://mme.modares.ac.ir/article_13737_dc8bdeba08b05398a3e5220a973cabce.pdf
A novel and comprehensive method for laser forming of cylindrical surfaces with arbitrary radius of curvature
Mehdi
Safari
عضو هیئت علمی/دانشگاه صنعتی اراک
author
text
article
2015
per
Laser forming is a flexible forming process that needs no hard tooling or external forces. In this paper, laser forming of cylindrical surfaces with arbitrary radius of curvature is investigated analytically and experimentally. As the laser forming process is a die-less forming process, production of a desired shape from initial blank is very difficult with this process. Because in the laser forming process, there are some variable parameters such as laser power, laser beam diameter, laser scanning speed and dimensions of initial blank that directly affect the final shape of the produced part. Also, in addition to above mentioned parameters, in the laser forming process of a cylindrical surface, a new parameter says number of irradiating lines is added to variable parameters. Therefore complexity of laser forming of a cylindrical surface will be more than a simple laser bending. In this paper, an analytical method for laser forming of cylindrical surfaces with arbitrary radius of curvature is proposed. In the proposed method, with the aim of technical limitations of laser machine such as laser power, laser beam diameter and laser scanning speed, the number of irradiating lines and the distance between neighbor lines are proposed for production cylindrical surfaces with arbitrary radius of curvature. Also, using experimental tests the performance and accuracy of the proposed method are investigated and verified. Analytical and experimental results show that with the proposed analytical method, cylindrical surfaces with any arbitrary radius of curvature can be produced with a very good accuracy.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
9
16
http://mme.modares.ac.ir/article_13738_f1131461029104ad0a4ec020629f8c6e.pdf
Breathing crack identification in beam-type structures using cat swarm optimization algorithm
Reza
Hassannejad
Assistant Professor of Mechanical Engineering-Faculty of University of Tabriz
author
Shahin
Tasoujian
دانشجوی کارشناسی دانشکده مهندسی مکانیک دانشگاه تبریز
author
Mohammad Reza
Alipour
دانشجوی کارشناسی دانشکده مهندسی مکانیک دانشگاه تبریز
author
text
article
2015
per
Early crack detection in structures prevents the occurrence of damage. Therefore, there is challenge in the literature to provide efficient methods in the field of structural health monitoring. A lot of researches that have been done on the crack identification in structures, are based on the models which ignore crack closure effects that make a significant error in the crack identification. Since it is more difficult to identify breathing crack than other damages, the purpose of this research is providing an efficient algorithm to identify breathing crack in beam-type structures which are important elements in various types of structures. In order to calculate natural frequencies of the beam accurately, in this research the fatigue crack model is used, which considers crack as breathing one with opening and closing behaviour. Then the problem of identifying crack parameters (location and depth of the crack) is defined as an optimization problem with the aim of minimizing the differences between natural frequencies calculated by the model and measured natural frequencies. In order to choose an appropriate algorithm to identify breathing crack, algorithms among various meta-heuristic algorithms are selected, which is able to identify the crack using only two natural frequencies. Regarding the surveys conducted, the optimization problem is solved using cat swarm optimization (CSO) algorithm. Moreover, in order to validate, the results are obtained for different crack parameters, have been compared with those of experimental tests. The results indicate that the proposed method has good accuracy
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
17
24
http://mme.modares.ac.ir/article_13736_46441cf1a947401f8884420187f01a13.pdf
Optimization of honeycomb impact attenuator using genetic algorithm based on response surface method and design of experiment; Part I: crashworthiness
Maryam
Alisadeghi
فارغ التحصیل کارشناسی ارشد
author
Jamshid
Fazilati
عضو هیات علمی/ پژوهشگاه هوافضای وزارت علوم، تحقیقات و فنآوری
author
text
article
2015
per
In this study, the design and optimization of a honeycomb energy absorber is performed using genetic algorithm. The main design goal is to absorb almost whole impact energy. Simultaneously, the reducing of the shock force level is also considered as a main objective. In the first part, the crashworthiness behavior of honeycomb structure is parametrically studied. The results are utilized in the second part to optimize shock absorber design. In this part, aluminum honeycomb structure under dynamic loading is investigated using simulation in LS-dyna finite element code. Parametric studies are invoked to identify the influence of different model parameters on crashworthiness characteristics of honeycomb structure. Reducing the computational cost, a repeatable model of 'Y' cross section column is numerically simulated. The effects of changes in material properties including Young's modulus, yield stress, tangent modulus, geometrical properties such as cell size, foil thickness, as well as the effects of impact velocity on the deformation behavior of the structure were investigated. A number of 25 different geometries with same height and various cell sizes and thicknesses are studied and effects of thickness and cell size on the energy absorption properties is investigated. Results showed that crashworthiness parameters such as mean and peak stress depend mainly on cell size and thickness values, while the friction coefficient and young's modulus are of less importance. Any change in absorber’s geometry affects the mean collapse stress more severe than the peak stress. In the meantime, thickness change is more effective in comparison with cell size change.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
25
36
http://mme.modares.ac.ir/article_13739_84a931f40c2917e158abda92903b99b7.pdf
Optimization of honeycomb impact attenuator using genetic algorithm based on response surface method and design of experiment; Part II: Optimization
Maryam
Alisadeghi
فارغ التحصیل کارشناسی ارشد
author
Jamshid
Fazilati
عضو هیات علمی/ پژوهشگاه هوافضای وزارت علوم، تحقیقات و فنآوری
author
text
article
2015
per
In this study, honeycomb energy absorber is optimized using genetic algorithm. The design goal is to absorb whole impact energy within a limited shock load level. First the crashworthiness and parameter sensitivity of honeycomb structure is extracted as explicit functions that are utilized to find optimized shock absorber configuration. Energy absorber must depreciate the impact kinetic energy and mitigate its defects on the structure and aboard. So the energy absorption capacity while the shock load is kept limited are the main design objectives. The volume and mass restrictions are also important objectives from an application point of view. Based on the simulation results available in the article Part I, the honeycomb response surfaces of crashworthiness parameters including the mean and peak crushing stresses are extracted. Utilizing the genetic algorithm based on response functions, the multi-objective optimized energy absorber is investigated. The main objective of the optimization problem is set to minimization of mass or volume while the maximum allowable shock and minimum energy absorption capacity are included as the problem constraints. The geometric specifications of honeycomb structure including cell-size, foil thickness, height and absorber face area are among the design variables with optimization outputs of energy absorption capacity, volume, mass, and shock level. Some optimization results are compared with those available in the literature and a typical problem is handled. Results show that mass and volume optimized geometries are almost similar and reduction of acceptable shock level makes the optimized geometry height to rise.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
37
45
http://mme.modares.ac.ir/article_13740_55701a2429ac0a477daa4c658c177e20.pdf
Analytical solutions for electro-elastic fields of periodic quantum nanostructures within transversely isotropic piezoelectric media: studying the geometry effects
Ehsan
Rashidinejad
Department of Civil Engineering - Sharif University of Technology
author
Hossein
Mohammad Shoja
استاد دانشگاه صنعتی شریف
author
text
article
2015
per
Accurate determination of the electro-elastic fields of quantum nanostructures within piezoelectric media is an important issue for realizing the electro-mechanical behavior of these nanostructures. In this paper, the governing partial differential equations corresponding to piezoelectric media containing quantum nanostructures are presented and subsequently, generalized analytical solutions based on Fourier series technique are developed for determination of the coupled electro-elastic fields in transversely isotropic piezoelectric barrier due to periodically distributed quantum nanostructures. The electro-elastic couplings of the piezoelectric barrier as well as the interactions between the quantum nanostructures are exhibited within the framework of the presented analytical solution. It is observed that no electric field and no electric potential will be induced anywhere in the medium for periodic distribution of quantum wires. The presented analytical solution is capable of treating different shapes and geometries of quantum wires/quantum dots. The electro-elastic fields of various shapes of sections of quantum wires and different geometries of quantum dots are studied and the effects of the geometry of periodically distributed quantum nanostructures are demonstrated. The results show that geometry of quantum nanostructures may highly affect the induced electro-elastic fields and therefore, accurate determination of the geometry of quantum nanostructures as well as the induced electro-elastic fields would be essential for employment of these nanostructures in different fields of research and technology.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
46
54
http://mme.modares.ac.ir/article_13745_440037cf165292e6f4e8722287d5cd76.pdf
Fabrication of Al5083/TiO2 surface composite by friction stir processing and investigation of microstructural, mechanical and wear properties
Saeed
Ahmadi Fard
دانشجوی کارشناسی ارشد، مهندسی مواد، دانشگاه بوعلی سینا، همدان
author
Shahab
Kazemi
استادیار، مهندسی مواد، دانشگاه بوعلی سینا، همدان
author
Akbar
Heidarpour
هیئت علمی
author
text
article
2015
per
The fabrication of nano‐composites is quite challenging because uniform dispersion of nano‐sized reinforcements in metallic substrate is difficult to achieve using powder metallurgy or liquid processing methods. Friction stir processing (FSP) is a new solid-state process used to modify the refinement of microstructure, improvement of material’s mechanical properties and production of surface layer composites. In this investigation via friction stir processing, metal matrix composite surface (MMCs) was fabricated on surface of 5083 aluminum sheets by means of 5 μm and 80 nm TiO2 particles. The friction processed surface composite layer was analyzed throughoptical and scanning electron microscopical studies. Effects of reinforcing particle size and FSP pass number on the microstructure, microhardness, on tensile and wear properties of the developed surfaces were investigated. Results show that the created nanocomposite layer by TiO2 particles exhibits a microstructure with smaller grains and higher hardness, strength, and elongation compared to the composite TiO2 layer by particles. Increasing FSP pass number results in improved distribution of particles, finer grains, and higher hardness, strength, elongation, and wear resistance. The surface composite layer resulted in four passes with change in rotation direction with nano particle reinforcement exhibited better properties in hardness, tensile behavior and wear resistance compared tothe behavior of the base metal.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
55
62
http://mme.modares.ac.ir/article_13743_c484298696f44a4092ca4d3fb5980bda.pdf
Practical Performance Comparison of Pole placement and Sliding Mode Controller for Position Control of Cable-driven Parallel Robots Using Visual Servoing
Hassan
Bayani
فارق التحصیل کارشناسی ارشد مکاترونیک دانشگاه تهران- آزمایشگاه تعامل انسان و ربات
author
Mehdi
Tale Masouleh
استادیار مهندسی مکاترونیک دانشکده علوم و فنون نوین دانشگاه تهران-آزمایشگاه تعامل انسان و ربات
author
Ahmad
Kalhor
استادیار دانشکده علوم و فنون نوین دانشگاه تهران- آزمایشگاه تعامل انسان و ربات
author
text
article
2015
per
This paper presents implementation of position control for planar cable-driven parallel robots using Visual servoing. The main contribution of this paper contains three objectives. First, a method is used toward kinematic modeling of the robot using four-bar linkage kinematic concept, which could be used in online control approaches for real-time purposes due to decreasing of the unknown parameters and computation time. In order to track the position of End-Effector, an online image processing procedure is developed and implemented. Finally, as the third contribution, two different controllers in classic and modern approaches are applied in order to validate the model with plant and obtain the most promising controller. As classic controller, pole placement approach is suggested and results demonstrate weaknesses in modeling the uncertainties although they represent acceptable performance. Due to the latter incapability, sliding mode controller is utilized and experimental tests represent effectiveness of this method. Result of the latter procedure is an inimitable operation on the desired task however, it suffers from chattering effect. Moreover, results of these controllers confirm accommodation between the model and robot. The whole procedure imposed, could be applied for any kind of cable-driven parallel robot.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
63
74
http://mme.modares.ac.ir/article_13744_fbc8bf92ed7795c9a01163f231fa2676.pdf
Pinning controllability of dynamical networks based on synchronized motion performance
Ali
Ghaffari
K.N. Toosi university of technology
author
Soleyman
Arebi
K.N.Toosi university of technology
author
text
article
2015
per
The right selection of the type and the number of driver nodes, play an important role in improving the controllability and the performance of the dynamical networks. In this paper the controllability and the performance of a network has been studied when a new approach for selecting the driver nodes, based on the three main node centrality criteria, has been proposed. For each criterion, the percentage of the least number of driver nodes to achieve the desired performance has been calculated for several network model structures. The results for pure random networks show that for the ‘’betweenness centrality criterion’’ the number of driver nodes is minimal. Similar results hold for Small World networks subject to the fact that for dense, the number of driver nodes increases. It is shown that the ‘’closseness centrality criterion’’ is the proper choice for the State Free networks especially when the network is dense. Another important result is that in Small World networks, increasing the nearest neighborhood coefficient, decrease the number of driver nodes for a desired performance. Similar results hold for Scale Free networks where increasing the heterogeneity coefficient improves the network pinning controllability.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
75
83
http://mme.modares.ac.ir/article_13746_cb3d864dd3644a7fccde9e21149b464a.pdf
Stress intensity factor calculation for surface crack in a family of thin and thick rotating disks using two dimensional weight functions
Rahmatollah
Ghajar
استاد دانشگاه خواجه نصیر-
author
Meysam
Davoodabadi
دانشجو - دانشگاه خواجه نصیر
author
Hamed
Saeidi Googarchin
عضو هیات علمی دانشگاه علم و صنعت
author
text
article
2015
per
A family of rotating disks used in Iranian turbine and compressor industry is investigated. Mechanical and thermal loads due to working condition would lead to the crack initiation in the inner surface of the disk. The aim of this paper is the development of the two-dimensional weight function for the rotating disks containing semi-elliptical longitudinal cracks. The general form of the two-dimensional weight function is related to the proposed weight functions for embedded cracked domain in literature. In order to determine the unknown coefficient of the weight function, the reference stress intensity factors for cracked geometry subjected to reference loads are calculated. The analysis indicated that the results are independent of the number of terms in proposed weight function expansion. Extracting the weight function for disks with from 90 to 420 mm thickness enables one to predict the stress intensity factor for cracks in the structure subjected to arbitrary loading. The stress intensity factor for each point on the crack front subjecting to one or two dimensional loads would be calculated using the derived weight function. The results reveal that the increasing of the height to thickness ratio in rotating disks leads to the increase of the stress intensity factor for high depth ratio crack ones. Results show that the configuration of the disk sections affects the stress intensity factors of the same aspect ratio cracks in the structures. The comparison of the results obtained from the weight function method and those obtained with FEM are in good agreement.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
84
94
http://mme.modares.ac.ir/article_13747_6b528d6d042d7ad3088c80114216977b.pdf
Balance recovery of a quadruped robot by optimal regulation of contact forces and body accelerations
Seyed Ali Akbar
Moosavian
استاد دانشگاه خواجه نصیرالدین طوسی
author
Mahdi
Khorram
دانشجو، دانشگاه خواجه نصیرالدین طوسی
author
text
article
2015
per
Maintaining and restoring robot balance in the presence of external disturbances is a significant capability for a quadruped robot. This is due the fact that these robots move over uneven terrains which may be themselves the sources of the disturbances. In this article, the balance recovery problem of a quadruped robot after an external disturbance will be investigated. To this end, as first stage, the equations of motion of a whole-body model of a robot and also a constraint elimination method will be proposed. In order to recover robot balance, the desired accelerations will be computed based on the concepts of a PD controller and by using the desired velocities and the positions of the main body. However, these accelerations maybe lead to slip stance feet or lose robot stability. Therefore, an optimization problem will be defined to calculate the admissible accelerations and the contact forces simultaneously. The optimal regulation of the contact forces will be done to distribute the contact forces among all stance legs to avoid feet slippage. Since the stability and the slippage avoidance conditions are formulated as linear constraints, the optimization can be solved as a linear constrained least squares error. To evaluate the effectiveness of the proposed algorithm, it will be examined on a quadruped robot in the simulation in two different case studies: in standing situation and walking gait. Finally, obtained results will be discussed.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
95
106
http://mme.modares.ac.ir/article_13741_aed66eb3a9cb7d761500e2ab4144dcca.pdf
Effective parameters on force of Ti-6Al-4V alloy blade preform extrusion process
Mehdi
Tajdari
دانشگاه آزاد اسلامی- واحد اراک- دانشکده فنی مهندسی- گروه مکانیک
author
Ali
Abdollahi Khangahi
دانشگاه مالک اشتر
author
Hamid
Arabi
محقق ارشد
author
text
article
2015
per
"DEFORM" three-dimensional finite element software is used to describe the behavior of plastic deformation of Ti-6Al-4V workpiece during blade preform extrusion process. Under different conditions of extrusion, numerical analysis of the process force parameter during extrusion process is presented. The relative effects of billet temperature, friction coefficient and die temperature on process force were investigated. To determine the process friction coefficient, the ring compression test of Ti-6Al-4V alloy with glass lubrication was performed. Also experimental tests were successfully done in order to manufacture blade preform. It was observed that billet temperature has much effect on force of Ti-6Al-4V alloy blade preform extrusion process. Die temperature has effect on the process force but its effect is not as much as the effect of the billet temperature. By increasing of the die temperature, the process force decreases. Experimental tests showed that the billet transfer process from the furnace to die has important effect on done or not done of the extrusion process because the billet transfer process from the furnace to die is cause of alters the billet initial temperature just before extrusion process. By reducing of the placing and transfer time of billet from the furnace to die, due to the vicinity of the billet and air, billet temperature have less reduction and therefore it becomes easier to shape. Also by increasing the friction coefficient, the force required for extrusion of Ti-6Al-4V alloy blades preform increased.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
107
112
http://mme.modares.ac.ir/article_13748_57653326e84b3e5b30ab0d63daf7830b.pdf
Theoretical and experimental investigation of notch effect on fatigue life of cylindrical HSLA100 steel specimens in rotating bending load
Javad
Amirian
دانشگاه صنعتی اصفهان
author
Hesam
Safari
دانشگاه صنعتی اصفهان
author
Mehdi
Shirani
دانشگاه صنعتی اصفهان
author
Saeed
Shabani
دانشگاه صنعتی اصفهان
author
text
article
2015
per
This research investigates notch effect on fatigue life of HSLA100 steel which is widely applicable in the marine industry. Experimental tensile tests and rotating bending fatigue tests were performed on both smooth and notched cylindrical specimens and the corresponding mechanical properties and S-N curves were obtained. To better investigate the notch and also size effect on fatigue life of the specimens, two different notch geometries and specimen dimensions were used. To calculate the fatigue strength factor, stress distribution under bending load is simulated for smooth and notched specimens. Then, the stress distribution under bending load is converted to stress distribution under rotating bending load using an in-house developed code. Finally, using an in-house developed code, the fatigue strength factor of the specimens is calculated by weakest link theory. In order to better investigate the weakest-link theory, in calculating the fatigue strength factor, this factor is calculated from the classical methods and compared with experimental results. Finally, Comparison of theoretical with experimental results shows that the weakest-link theory gives better predictions than other classical methods and the results are closer to experimental ones. Also, Weakest-link theory uses the finite element results to predict notch effect. This facilitates the use of this theory in fatigue design of complicated specimens.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
113
120
http://mme.modares.ac.ir/article_13750_ee26b46e0ae6f90afd43bd9f858ed020.pdf
Hydraulic and Thermal Modeling and Optimization of Rectangular Finned Multi Stream Plate-Fin Heat Exchangers by Genetic Algorithm
Amir Farhang
Sotoodeh
دانشجوی دکتری، مهندسی مکانیک، گروه سیستمهای انرژی، دانشکده مهندسی مکانیک،
دانشگاه صنعتی خواجه نصیرالدین طوسی، تهران
author
Majid
Amidpour
استاد دانشگاه خواجه نصیرالدین طوسی
author
Mehrangiz
Ghazi
استادیار، گروه مکانیک، واحد تاکستان، دانشگاه آزاد اسلامی، تاکستان، ایران
author
text
article
2015
per
The modeling and optimization of a rectangular finned multi stream plate-fin heat exchangers is presented in this paper. The proposed method for thermal modeling of this type of heat exchangers is based on uniform heat distribution along the plates. So, the heat streams are distributed along the multi stream heat exchanger based on two principles: equal quantity of stream channel distribution and uniform heat distribution in each of the channels. The geometric, thermal and hydraulic modeling and design of the multi stream heat exchanger is carried out based on rectangular fin specifications. The total annual cost (TAC), the summation of capital investment and operating and maintenance costs are regarded as objective function to be minimized. The main variables are heat exchanger core dimension such as length, width, height and the fin geometric parameters such as fin pitch and height. The genetic algorithm is utilized as optimization tool to minimize the total annual cost of the multi stream plate fin heat exchanger. The proposed method is applied to a case study. The results of the current method is compared with the literatures.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
121
131
http://mme.modares.ac.ir/article_13749_d64bdd01b28d658c978949102415e0b9.pdf
Nonlinear Optimal Control of Orbital Rendezvous Problem for Circular and Elliptical Target Orbit
Mohammad
Navabi
استادیار مهندسی هوافضا -دانشکده فناوریهای نوین -دانشگاه شهید بهشتی
author
Mehdi
Reza Akhloumadi
دانشگاه شهبد بهشتی- دانشکده فناوری های نوین- مهندسی هوافضا
author
text
article
2015
per
The orbital rendezvous and docking with Position and attitude nonlinear dynamics is one of the most challenging problems in the Aerospace engineering. The attitude and position of a chaser spacecraft, desired to rendezvous with a target spacecraft, have to be determined with respect to the target, as a result relative equations have to be considered. The chaser is controlled by actuators to rendezvous safely and stably under the conditions and requirements. In this paper rendezvous dynamics for target in a circular orbit is assumed as nonlinear second-order clohessy-wiltshire relative motion equations. Shauner and hempel relative equations are considered for target in elliptical orbit. Cost function has been chosen in a manner to minimize the control effort and to give smooth states. Nonlinear optimal control for rendezvous with a target in circular orbit using state dependent riccati equation by means of eigen vectors of the Hamiltonian matric is compared with linear quadratic regulator method for both linear and nonlinear systems and then stability and robustness of the results are analysed. Optimal control of a elliptical rendezvous is discussed independently. For navigational porpose it is important to express relative motion in inertial frame, this is accomplished by introducing an appropriate transformation.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
132
142
http://mme.modares.ac.ir/article_13773_0329cf34c32566cf8211e444be5d1494.pdf
Numerical simulation of darrieus wind turbine Using 6DOF model to consider the effect of inertia and the fluid-solid interaction
Alireza
Arab Golarche
Ferdowsi University Of Mashhad
author
Mohammad
Moghiman
استاد عضو هیئت علمی دانشگاه فردوسی مشهد
author
Seyyed Mohammad
Javadi MalAbad
Quchan University of Advanced Technology
author
text
article
2015
per
Unlike HAWT, Darrieus wind turbines is faced with the self-start problem and high fluctuations at output torque. Because of the need for techniques based on meshing and coupling Eulerian fluid equations and the Lagrangian equations for moving rigid body, the calculation of rigid body acceleration and fluctuations torque of VAWT is very complicated and it is a function of the moment of inertia of the turbine. In most studies, regardless of this effect, the angular velocity of turbine is assumed to be fixed. In this study, for calculating the turbine rotational speed and position, the sum of wind-driven aerodynamic forces and external forces caused by friction and generators are calculated and placed into Newton's second law to calculate the acceleration, and integrating it in time steps. The simulation is performed unsteady and dynamic mesh is used for moving the rotor. The results could check the interaction between wind and rigid blades on the in the process of increasing the rotational speed of turbine, and simulate the rotor from the moment of rest until the turbine reaches its final rotational speed. The causes of reduction in torque at low rotational speed is investigated and it has been shown that high dynamic stall and passing high exergy flow into the rotor without interaction with blades results the power reduction. Moment of inertia has significant impact on the frequency and amplitude of rotational velocity, fluctuations of output torque and output power, which is important in mechanical analysis of blades’ fatigue.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
143
152
http://mme.modares.ac.ir/article_13774_b9c8ab57ce47b49cbd0c657745fad8d1.pdf
Mechanical Behavior of Human Arteries in Large Deformation Using Non-Linear Elasticity Theory
Alireza
Saidi
دانشکده مهندسی مکانیک، دانشگاه شهید باهنر کرمان
author
Amin
Safi Jahanshahi
دانشجوی دکترا، مهندسی مکانیک، دانشگاه شهید باهنر کرمان
author
text
article
2015
per
Mechanical behavior of live cells and tissues is non-linear and their deformations are large. Using a suitable mechanical model that could predicts this behavior, is an important step in the prevention and treatment of various diseases and the production of artificial tissues. In this paper, using the non-linear elasticity theory and non-linear Mooney-Rivlin model, mechanical analysis of human arteries has been studied under internal pressure and axial tension. In the first By using the experimental study was conducted of biaxial test, the elastic constants of the arteries are calculated. For modeling, the arteries are considered as long homogeneous and isotropic cylinders. Radial and circumferential stress distribution on the minimum and maximum blood pressure is calculated. Variation of artery radius due to internal pressure is calculated and compared with the reported experimental data, and a good agreement is seen. The stress distribution curves versus radius are plotted which show that the inner layers of the arteries have much greater role in stress distribution than the outer layers. The elastic constants which are calculated for different ages show that the arteries of older people become stiffer and their flexibility decrease.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
153
158
http://mme.modares.ac.ir/article_13775_74f3693156f6d4f9006bf8521da68933.pdf
Pool boiling enhancement by electrodeposited porous micro/nanostructured on copper surface
Amir
Mirza Gheitaghy
School of Mechanical Engineering, Iran University of Science and Technology
author
Hamid
Saffari
Associate Prof., Head of Department, School of Mechanical Engineering/ Iran University of Science and Technology
author
Jafar
Salehi
دانشکده مهندسی مکانیک، دانشگاه علم و صنعت ایران
author
text
article
2015
per
Boiling is a remarkably efficient heat transfer method and is commonly used in daily life and industrial applications. Changing the physical and chemical structure of hot surface in some methods as making a porosity in a manner of enhancing boiling process is an interesting topic in recent decay. In this paper, porous metal micro/nano structural surfaces is produced in order to augmentation of boiling heat transfer on copper surface by the one- and two-stage electrodeposition method. The pictures in micro and nanoscale are captured to identification of structure and surface characteristics as porosity and capillarity are estimated. Next, the effects of structures in enhancing the pool boiling are measured experimentally. So then, boiling heat transfer profiles that demonstrate heat flux versus wall superheat, are derived for water fluid. Pool boiling curves of enhanced surfaces is compared with polished surface and results of other researchers to determine the efficiency improvement. Furthermore, comparison the effect of electrodeposition process time on obtained structures shows higher porosity, capillary and strength of structure with lower process time (30 sec) lead to further enhancement of pool boiling.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
159
167
http://mme.modares.ac.ir/article_13776_2142fb0f5c0eff4bedd66c6b62055208.pdf
Numerical Investigation of Magnetic Nanoparticles Absorption in Healthy and Cancerous Tissue under the Influence of Non-Uniform Magnetic Field
Azadeh
Shahidian
عضو هیات علمی/دانشگاه صنعتی خواجه نصیرالدین طوسی (گروه انرژی)
author
Seyed Mohammad Ali
Nemati
دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Majid
Ghasemi
دانشگاه صنعتی خواجه نصیرالدین طوسی
author
text
article
2015
per
Recent development in applications of magnetic nanoparticles makes them a good candidate as drug carriers especially for tumor treatment. Therefore it is important to analyze the behavior of magnetic nanoparticles in the blood vessel and tissue. The purpose of the current study is to investigate the magnetic nanoparticles movement and absorption in blood vessel and healthy and cancerous tissue under the influence of non-uniform external magnetic field. An in house finite volume based code is developed and utilized to solve the coupled governing nonlinear differential equations, mass, momentum and concentration under the influence of non-uniform external magnetic field. The 2D cannel is considered as geometry of vessel and blood is assumed to be non-Newtonian. The power law equation is used for blood viscosity. Results show the absorption of magnetic nanoparticles is low in cancerous tissue without of magnetic field, but by applying magnetic field absorption of them multiplied. Also, ratio of magnetic nanoparticles absorption in healthy tissue to cancerous tissue decrease sorely by applying magnetic field. Therefore, treatment is more effective and has fewer side effects by applying magnetic field.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
168
174
http://mme.modares.ac.ir/article_13777_b2472c93e98b9c5ebad76140e49008e7.pdf
Investigation of Microhardness and White Layer in Milling of Hardened Steel Using Response Surface Methodology
Hamed
Hassanpour
tarbiat modares university, mechanical engineering
author
Mohammad Hossein
Sadeghi
استاد دانشگاه تربیت مدرس
author
Amir
Rasti
tarbiat modares university
author
text
article
2015
per
Hard steels are widely used in automotive industry, molding and production of well drilling bits because of its high wear resistance and strength. The tendency to hard machine of these steels is growing in order to achieve high dimensional and geometrical accuracy, increased productivity and improved workpiece properties. In this research, relation between cutting parameters and final surface integrity in hard milling process of a workpiece made out of 4340 steel while using minimum quantity lubrication system is studied. Different parameters were considered in three levels as main milling parameters including: cutting speed, feed rate, axial and radial depth of cut and consequently the effect of these parameters on surface microhardness and white layer thickness were studied using Response Surface Methodology (RSM). The analysis of variance (ANOVA) showed that a model of quadratic polynomial function would work perfectly in order to estimate microhardness and it can also estimate experimental results while a linear model can evaluate white layer thickness changes, better. Also, Statistical analysis revealed that all cutting parameters increase microhardness and white layer thickness. Feed rate with 73.1% and cutting speed with 14.4% had more effect on microhardness comparatively. White layer thickness also varied between 7.6 μm to 16.1 μm while different cutting conditions were applied and cutting speed with 81.3% and feed rate with 9.4% had the most effects on white layer thickness.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
175
182
http://mme.modares.ac.ir/article_13778_01b7341fed4b013761f11cd708ddfc01.pdf
Effect of welding current on microstructure, hardness and wear resistance of hardfacing deposit on carbon steel
Majid
Mohamadi Ziarani
دبیر - آموزش و پرورش
author
Nasrallah
Bani Mostafa Arab
استادیار دانشکده مکانیک دانشکاه تربیت دبیر شهید رجایی
author
Hassan
Jafari
استادیار دانشکده مکانیک دانشگاه تربیت دبیر شهید رجایی
author
text
article
2015
per
Engineering components during service are exposed to destructive phenomena such as wear which may lead to their destruction. For their protection and reduction of costs of replacement of these defective components and also increasing productivity, attention is given to welding processes for depositing a wear-resistant layer on the components. In this research, the effect of welding current on last layer weld quality deposited on carbon steel by shielded metal arc welding process using Fe-based hardfacing electrodes is investigated. The chemical composition of the weld deposit layers was studied by quantometery. Optical and scanning electron microscopes, energy dispersive X-ray fluorescence and X-ray diffraction were used for microstructural studies. Microhardness and pin on disk wear tests were also employed for microhardness and wear resistance evaluations. The metallography and X-ray diffraction results show presence of martensite and retained austenite in the microstructure of the last deposited weld layer. The results of chemical analysis and microhardness and wear-resistant tests show that increasing the current increases weld dilution which leads to reduction of alloying elements affecting hardness and wear resistance of the weld deposit and hence these properties decrease slightly. Evaluation of the worn surfaces shows that the wear mechanism on the last deposited layer is of abrasive wear type.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
183
188
http://mme.modares.ac.ir/article_13791_3437270c8fd364b9418e0ea4141b993c.pdf
Adaptive Second Order Sliding Mode Controller for Two-input Two output Uncertain Nonlinear Systems and Application to a 2-DOF Helicopter Model
Kazem
Zare
دانشگاه اصفهان
author
Hamid Reza
Koofigar
دانشگاه اصفهان
author
text
article
2015
per
In this paper, the adaptive second order sliding mode (SOSM) controller is designed for two input - two output (TITO) uncertain nonlinear systems and the robustness properties are ensured in the presence of uncertainties and bounded external disturbances. The objective is to design a controller that ensure stability and path tracking despite the effects of coupling. To this end, the system model is divided into two subsystems, and the coupling effects between such subsystems are considered as uncertainties. The sliding mode approach with PI sliding surface is used to remove the offset and converge the steady state error to zero. To avoid chattering phenomenon, Second order sliding mode method is proposed. Using adaptive switching gain, a new method is presented which unlike other methods, does not require the upper bound of the system uncertainties in the design procedure. Robustness properties against system uncertainties and external disturbances is shown by the Lyapunov stability theorem. Finally, the proposed method is used to control azimuth and elevation angle of as a laboratory helicopter with two degrees of freedom. Simulation results show performance of the algorithm in the presence of perturbations.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
189
199
http://mme.modares.ac.ir/article_13793_affd18bb06db0d416a2a2560d9cdf6c6.pdf
Nonlinear vibrations modeling and sensitivity analysis of the coupled roll and heave motions of a ship
Neda
Rahmat
دانشگاه یزد
author
Saeed
Ebrahimi
استادیار گروه مهندسی مکانیک- دانشگاه یزد
author
Abbas
Mazidi
دانشگاه یزد
author
text
article
2015
per
In recent decades, study of the behavior of ship motion in waves is considered by researchers. In this paper, mathematical modeling of nonlinear coupling of roll and heave modes of a ship under harmonic excitation in heave direction is studied. The method of multiple scales is used to solve nonlinear equations. Equations of motion in harmonic excitation is studied. In order to validate the responses obtained by the method of multiple scales, the response obtained for a sample is compared with the numerical solution of the equation and good agreement is obtained. Analysis ship motion requires time consuming computations in large scaled model. In addition to evalution of nonlinear coupling roll motion with heave in forced vibrations, the motion is modeled with a simple mechanical system includes mass–spring-damper and pendulum under identical conditions and the response of equal system with response of the original system is consistent. Sensitivity analysis was carried out for nonlinear coupling of roll and heave in harmonic excitation with local and partial derivative methods and the results from two methods is compared.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
200
208
http://mme.modares.ac.ir/article_13794_10a2f7da224a076391a4916d1192972b.pdf
Nonlinear fault-tolerant flight control for a transport aircraft in presence of actuators fault and failure
Mohammad
Navabi
استادیار مهندسی هوافضا -دانشکده فناوریهای نوین -دانشگاه شهید بهشتی
author
Parastoo
Roozgard
دانشگاه شهید بهشتی، مهندسی هوافضا، دینامیک پرواز و کنترل
author
text
article
2015
per
Aircraft actuator damage is one of the main causes of the loss of control during the flight. The Aircraft dynamic are severely affected by the faults and failures and if the corrective command signals are not supplied immediately, damages will lead aircraft to catastrophic consequences such as instability and system performance degradation and deadly plane crashes will be occurred. This paper presents a fault-tolerant control technique based on nonlinear optimal control method using State-Dependent Riccati Equation. Two fault and failure scenarios including loss of elevator effectiveness and aileron hard-over for a large transport aircraft is considered and the performance of State-Dependent Riccati Equation method is evaluated in comparison with its linear counterpart (Linear Quadratic Regulator). For the first time this technique as a fault-tolerant flight control method has used in the internal investigations. Simulation results demonstrate the effectiveness of the proposed nonlinear approach in restoring stability and maintaining the flight path.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
209
220
http://mme.modares.ac.ir/article_13801_92bf3a2d566b75df671566ea6b6df414.pdf
Control System Design Based on Position Feedback and Disturbance Estimation in Dynamic Positioning of Marine Vessels
Mehdi
Loueipour
PhD Student / Isfahan University of Technology
author
Mohammad
Danesh
author
Mehdi
Keshmiri
Faculty / Isfahan University of Technology
author
Mohsen
Mojiri
Faculty / Isfahan University of Technology
author
text
article
2015
per
This paper presents a new approch in the design of output feedback control system based on disturbance observer for dynamic positioning vessels. The proposed control system includes a controller and a structure of a modified notch filter and a nonlinear observer. The filter is used for estimating low-frequency motions and removing the wave-frequency motions by using vessel position mesurement. The low-frequency disturbances and vessel-velocites are estimated in nonliner observer using the low-frequency vessel motion. In this structre, wave filtering and low-frequency motion estimation are independent from the estimation of low-frequency disturbances and vessel velocities. It causes to incease the accuracy of filtering and estimation which results in desirable performance of control system. Also, filtering is independent of the vessel and low frequency disturbances models, and therefore it is not affected by modeling uncertainty. The effect of wave filtering and low-frequency disturbances estimation in DP control system from the point of reducing control signal flactutions were evaluated with numerical simulation. This is important in view of reduction of wear and tear in propaltion system and fuel consumption in a surface vessel. Futhermore, simulation results show that the proposed method has better performances in comparision with conventional method.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
221
231
http://mme.modares.ac.ir/article_13802_b481fb232409f71a96997588b2f55417.pdf
Simulation Study on the Thermal Performance of a direct-expansion solar-assisted heat pump for water heating in Kermanshah climate
Habibollah
Safarzarzadeh
استادیار دانشگاه رازی کرمانشاه
مدیر گروه مهندسی مکانیک دانشگاه رازی
author
Sobhan
Fathollahi
دانشجوی کارشناسی ارشد رشته مهندسی مکانیک دانشگاه رازی
author
text
article
2015
per
Direct-expansion solar-assisted heat pumps (DX-SAHP) have been used widely to heat the consuming water of buildings and industrial facilities, domestic and industrial space heating and also, air conditioning. These systems transfer energy from lower temperature source to a higher temperature source. In DX-SAHP systems, In order to optimize the heat transfer of solar radiation to the refrigerant, the flat plate solar collector is used as the evaporator. In this paper, the thermal performance of a DX-SAHP has been studied using numerical simulation for heating the water of a house in Kermanshah. The system mainly employs a bare ﬂat-plate solar collector with a surface area of 4 m2, a hot water tank with the volume of 150 L, a rotary-type hermetic compressor, a thermostatic expansion valve and R-134a is also used as working ﬂuid in the system. The results show that the hours of system operation, during different months in the climate of Kermanshah, vary between 37 to 130 hours and the monthly average COP and the solar collector efficiency vary between 3.96 to 6.71 and 68 to 99 percent respectively. The effect of various parameters, including solar radiation, ambient temperature, collector area, compressor speed, number of collector cover and wind speed have been analyzed on the thermal performance of the system.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
232
242
http://mme.modares.ac.ir/article_13803_b4ffd58dd42064d9671a3db9856e9c03.pdf
Optimization of effective parameters on isotropic plates with regular polygonal cutouts using particle swarm Algorithm
Mohammad
Jafari
استادیار دانشگاه صنعتی شاهرود
author
Seyed Ahmad
Mahmodzadeh Hosseini
دانشجوی دانشگاه شاهرود
author
text
article
2015
per
One of the designers concerns is structural failure as a result of stress concentration in the geometrical discontinuities. Stress concentration factor in the presence of cutout, is a key parameter in reducing the structural load-bearing capacity. In the analysis of perforated isotropic plates, the effective parameters on stress distribution around cutouts are the cutout geometry, curvature radius of cutout corner, rotation angle of cutout and load angle. In this study, using PSO method it has been tried to introduce the optimum parameters to achieve the minimum amount of stress around the n-sided cutouts in isotropic plates under uniaxial tension. In this paper, an analytical method has been used to calculate the stress around cutouts with different shapes. According to this method, by using the conformal mapping, Muskhelishvili’s complex variable method which is only for circular and elliptical cutouts, has been developed for the other cutouts. The results presented in this case shows that by choosing the appropriate shape of cutout and the optimal effective parameters, stress concentration factor can be significantly reduced and lowest stress concentration factor rather than amount of stress concentration corresponding to circular hole can be achieved.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
243
253
http://mme.modares.ac.ir/article_13804_3cd64542d5a27ab02870a36f9b094ed5.pdf
A Survey on Time Domain MIMO Identification Techniques for Experimental and Operational Modal Analysis
Seyed Ali
Hosseini Kordkheili
دانشیار، دانشکده مهندسی هوافضا-
دانشگاه صنعتی شریف
author
Sajjad
Hajirezaie
دانشجوی کارشناسی ارشد/ دانشگاه صنعتی شریف - دانشکده مهندسی هوافضا
author
Seyed Hassan
Momeni Massuleh
دانشجوی دکتری/ دانشگاه صنعتی شریف - دانشکده مهندسی هوافضا
author
text
article
2015
per
A comparison between three different time domain MIMO modal identification techniques i.e. ERA, EITD and PRCE is performed. The comparison is executed for discontinuous (mass and spring) and continuous (beam) systems in two different cases; i. e. experimental and operational modal analysis techniques. For this purpose the modal parameters of the system are measured using both direct time history data of impulse response (EMA) as well as correlation function of random response of the structure (OMA). From the results it is noted that some parameters like sampling frequency and total recording time have effect on their accuracy. Sensitivities of the results due to these parameters are measured and reported for all three considered methods. For this purpose the effecting parameters are altered between a couple of values and the sensitivity of the results is studied for all methods in both EMA and OMA cases. Finally, a comparison between the results of different methods is done and the accuracy of the methods is studied. It is concluded that ERA is the most accurate and reliable method with the least sensitivity to effecting parameters in both EMA and OMA cases.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
254
264
http://mme.modares.ac.ir/article_13805_1b9360dd94c7b22d76513607aba31836.pdf
Study of convergence in Isogeometric method in the framework of “Diametral Compression Test” elasticity problem with point load singularity
Behrooz
Hassani
Professor/Department of Mechanical Engineering, Ferdowsi University
author
Emad
Bidkhori
author
text
article
2015
per
Applying and combining h and p refinement techniques in isogeometric method with the possibility of continuity elevation that this method provides, convergence and error of using different kinds of shape functions with different orders and continuities is investigated. It is done in a numerical analysis framework of a practical and well known problem called “Diametral Compression Test”. The advantage of this case is its circular geometry, since IGA provides designers with high potency of the possibility of using minimum elements to make the exact circular geometry. The point load inserts singularity to the problem. The refinement is utilized uniformly as the effective parameters are limited to the kind, order and continuity of shape functions. With different refinement techniques the convergence of approximated solution to the exact solution of linear elasticity is examined. It is concluded that with the singularity that mentioned, the error in IGA is not necessarily reduced with raise in order, more precisely the level of continuity is another important issue to determine error raise. It is also seen that in the presence of point load singularity the rate of error converges to the same value for all degrees of NURBS and lagrangian shape functions with any continuity. At the beginning of refinement process the minimum number of elements is used to make the process clearer to understand. In next steps h and p techniques and their combination is used to refine the model.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
265
271
http://mme.modares.ac.ir/article_13806_a7f9fe2cc210f16978febbba034ebd26.pdf
Finite element formulation for non-linear static analysis of orthotropic plates using two-variable refined plate theory
Seyed Jafar
Rouzegar
استادیاردانشگاه صنعتی شیراز
author
Seyed Mohammad
Sayedain
دانشگاه صنعتی شیراز
author
text
article
2015
per
A finite element formulation for bending analysis of isotropic and orthotropic plates based on two-variable refined plate theory is developed in this paper. The two-variable refined plate theory which can be used for both thin and thick plates predicts parabolic variation of transverse shear stresses across the plate thickness and therefore, it does not need shear correction factor in the formulation and the zero stress conditions are satisfied on free surfaces. The von-Karman nonlinear terms are considered in strain-displacement equations and governing equations are derived using the Hamilton's principle. After constructing weak form equations, a new 4-node rectangular plate element with six degrees of freedom at each node is used for discretization of the domain. The non-linear coupled governing equations are solved by Newton–Raphson method. The finite element code is written in MATLAB which can be used for analysis of thin and thick, isotropic and orthotropic plates with various boundary conditions. Some benchmark problems are solved by the developed code and the obtained displacements and stresses are compared with the existing results in the literature which show the accuracy and efficiency of presented finite element formulation.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
272
278
http://mme.modares.ac.ir/article_13808_65b5e8ac87e1b687a9403dbe8b182516.pdf
A conceptual model for the dynamical analysis of vehicle wheelhouse in the early stage of design
Omid
Zargar
دانشجوی کارشناسی ارشد پردیس دانشکده های فنی دانشگاه تهران دانشکده مهنذسی مکانیک
author
Abolfazl
Masoumi
دانشیار پردیس دانشکده های فنی دانشگاه تهران دانشکده مهندسی مکانیک
author
Mohammad Reza
Ashoori
دانشیار دانشگاه سمنان دانشکده مهندسی مکانیک
author
text
article
2015
per
Nowadays the Computer Aided Engineering (CAE) technique is widely used for improving Noise Vibration Harshness (NVH) performance of vehicles. High complexities in the Body In White (BIW) of vehicles lead the developed CAE models to become complex by which the optimization process will become very hard. Concept modeling could be a suitable replacement to overcome the mentioned limitations. Dynamic characteristics such as natural frequencies and mode shapes could be studied in the early phase of design with very low amount of calculations with the concept model. For this purpose, a developed concept model has been presented for the wheelhouse. The developed concept model uses approximated equivalent beam elements to model the beam like and panels of the structures. Also, the experimental test and numerical model have been utilized for the validation of the developed concept model. Two criteria of natural frequencies and corresponding mode shapes have been considered as the measure of validation. The results showed good correlation with corresponding advanced CAE models as well as experimental tests in low frequency range. The results showed that the developed concept model in this research is a powerful and effective tool to enhance and optimize the NVH performance of the vehicle in the early stage of design.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
279
286
http://mme.modares.ac.ir/article_13807_ea0945b2dd74139b005127d023a40ea6.pdf
Investigation of Variation of Friction Coefficient and Frictional Stress Using a New Designed Device
Amin
Rouzbeh
دانشگاه تبریز
author
Tajbakhsh
Navid Chakherlou
هیئت علمی دانشگاه
author
Hadi
Taghizadeh
دانشگاه تبریز
author
text
article
2015
per
In this paper, the variation of coefficient of friction, which is one of the main and important parameters in fretting fatigue, has been investigated experimentally. Measuring of coefficient of friction has been performed with the designed device by the researchers. The advantage of using the above device is that it can almost accurately measure the contact pressure and friction force and thus the coefficient of friction. Al alloy 2024-T3 has been used as it is the frequently used alloy in aerospace structures. The coefficient of friction is considered here as a parameter which is a function of normal and cyclic axial load. Another important point in performing the test is the variation of frictional stress at different normal and axial loads which is measured. Results show that as the normal load increases, the coefficient of friction reduces but the frictional stress increases. Changing the frictional stress is the main parameter in investigating wear between interfaces. The above results can be applied in numerical analyses such as life prediction and/or predicting joints fracture section such as double shear lap joints which experience fretting fatigue.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
287
294
http://mme.modares.ac.ir/article_13810_b346c96cf7c39b091b820625bfe3dd1f.pdf
Experimental investigation and simulation of the effects of friction drilling parameters on length of bush in stainless steel AISI304 sheet
Sajjad
Khisheh
دانشجوی دکتری/دانشگاه بیرجند
author
Hossein
Amirabadi
استادیار گروه مکانیک دانشگاه بیرجند
author
Seyed Mohammad Hossein
Seyedkashi
استادیار/دانشگاه بیرجند
author
text
article
2015
per
Friction drilling is a nontraditional hole-making process used to create and form the holes in thin sheets. The process involves penetration of a rotating conical tool into a sheet metal work piece and creation of a bushed hole in a single step. The tools are conical without having cutting edges, and the heat caused by friction between the tool and workpiece is used to soften the material, penetrate into the workpiece and make the bush. In this process, the temperature is high, and so that the deformation. The simulation by finite element analysis is a useful tool for understanding the material flow, stress, strain and length of bush. In this research, Abacus software was used to simulate the behavior of friction drilling. To verify the simulation results, the length of bushes created by tools with different diameters at different rotational speeds and federate were measured, and results were compared with experimental data. The aim of this study was to determine the process parameters to provide the bush with a uniform thickness, and study their effect on the shape of bush. Therefore, DOE was performed using a full factorial method and results were interpreted using ANOVA. Results showed that the tool diameter has the greatest effect (95%) on the length of bush during friction drilling, then feed rate (3%) and finally rotational speed (2%) has the smallest effect.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
295
302
http://mme.modares.ac.ir/article_13809_d404067688454fe3c17ea5b68ef70e35.pdf
Simulation and Analysis of Bushehr Nuclear Power Plant Steam Generator
Ataollah
Rabiee
shiraz university
author
Amir Hossein
Kamalinia
دانشگاه شیراز
author
Kamal
Hadad
دانشگاه شیراز
author
text
article
2015
per
Steam generators as an interface between first and second loop of light water nuclear power plants is very important in design and safety analysis. Thermo hydraulic analysis can affect the design and operation of a horizontal steam generator using prediction of vapor distribution. In this kind of thermo hydraulic analysis, simulation and study of the tube bundles is crucial in design and safety study of the steam generator two phase flow field. In this research, due to high complexity of the numerical simulation, the tube bundles have been assumed as the porous media. Two phase flow field correlations such as interfacial drag force and tube bundle resistance force have obtained by the equations that have been reported in the similar computational fluid dynamic researches. The heat transfer from primary side fluid to the secondary is calculated three-dimensionally each iteration and is supplied as a heat source on the secondary flow field calculation. Besides porous media flow field validation, decrease of computational domain has been studied using appropriate boundary conditions. It was observed that the computed void fraction compared to the experimental results show better accuracy than similar computational fluid dynamic investigations
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
303
310
http://mme.modares.ac.ir/article_13811_95380e1b71dc2603a90b1fbbee7e728f.pdf
3D-Dynamic Modeling and simulation of biological nanoparticle motion using AFM nano–robot
Moein
Taheri
Assistant Professor, Department of Mechanical Engineering, Faculty of Engineering, Arak University, Arak, Iran
author
text
article
2015
per
In nanomanipulation using atomic force microscopy, for the displacement of various micro/nanoparticles, calculation of accurate critical force and time of manipulation in order to not damage and precise manipulation of micro/nanoparticles, is necessary. To achieve this goal requires accurate modeling of kinematics and dynamics of a two-dimensional nanomanipulation that already has been done. In this paper, three-dimensional nanomanipulation modeling and simulation dynamic has been done for more simulation results closer to the results of real nanomanipulation. For this purpose, by taking a spherical shape for micro/nanoparticle, three-dimensional kinematic relations manipulation extracted. Then, JKR contact model for use in manipulation provided and rectangular beam stiffness equations derived in three dimensions. In the final stage of the modeling of the dynamics of the three-dimensional micro/nanoparticles to extract force equations and critical time manipulation obtained. Then the equations obtained by simulation, three-dimensional manipulation amount of force and critical time for both DNA and platelets biological particle is calculated. The results indicate start rolling motion of the particles studied before rolling around on the x-axis and y axis and z as well as the critical need for displacement of particles of the platelet-derived DNA.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
311
316
http://mme.modares.ac.ir/article_13812_cee625ff8cb4a44b30b3115bac0e721e.pdf
Path Planning of 3-RRR Planar Parallel Robot by Avoiding Mechanical Interferences via Artificial Potential Field
Mehdi
Tale Masouleh
استادیار مهندسی مکاترونیک دانشکده علوم و فنون نوین دانشگاه تهران-آزمایشگاه تعامل انسان و ربات
author
Hossein
Kazemi
Faculty of Mechanical Engineering, Sharif University of Technology
author
Pouria
Nozari Porshokuhi
Faculty of Mechanical Engineering, Sharif University of Technology
author
Roya
Sabbagh Novin
PhD Student, Mechanical Engineering Department, University of Utah
author
text
article
2015
per
This paper deals with the collision-free path planning of planar parallel robot by avoiding mechanical interferences and obstacle within the workspace. For this purpose, an Artificial Potential Field approach is developed. As the main contribution of this paper, In order to circumvent the local minima problem of the potential fields, a novel approach is proposed which is a combination of Potential Field approach, Fuzzy Logic and also a novel algorithm consisting of Following Obstacle as well as Virtual Obstacle methods, as a hybrid method. Moreover, the inverse kinematic problem of the 3-RRR planar parallel robot is analyzed and then the aforementioned hybrid method is applied to this mechanism in singular-free case. It is worth mentioning that, in this paper, all the probable collisions, i.e., the collision between the mechanism and the obstacles and also among the links, are taken into accounts. Two general cases have been considered in collision-free path planning simulation; the first case considered a mobile robot in several workspaces and the second one was assigned to the 3-RRR planar parallel robot path planning. Results of the simulations, which are implemented in C programming language for the sake of real-time purposes. reveal that for the both cases, the newly proposed hybrid path planning method is efficient enough for the mobile robot, or the end-effector of the planar parallel robot to reach the goal without colliding with the obstacles.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
317
325
http://mme.modares.ac.ir/article_13813_6e5a8d20d118cecf5722af59830d2f1c.pdf
A discontinuous Galerkin method for two-phase flow in porous media using modified MLP slope limiter
Mehdi
Jamei
Professor (Assistant) at
Behbahan Khatam Alanbia University of Technology
author
Hamid Reza
Ghafouri
Professor of Civil Engineering, Dean of Engineering Faculty
Shahid Chamran University, Ahvaz, Iran
author
text
article
2015
per
In this article, a numerical solution of incompressible two-phase flow in isothermal condition, based on wetting pressure-wetting saturation formulation (Pw,Sw) using high order primal discontinuous Galerkin (DG) methods is considered which can capture the shock fronts of two-phase flow in heterogeneous porous media. In this presented model, the velocity field is reconstructed by a H(div) post-process in lowest order of Raviart-Thomas space (RT0). Also in this study, the scaled penalty and weighted average (harmonic average) formulation significantly improve the especial discretization formulation of governing equations which cause to reduce the instabilities in heterogamous media. The modified MLP slope limiter is used to remove the non-physical saturation values at end of each time step. In this study, the slope limiter should be considered as one of the main novelties due to the impressive effects in results stabilization. The proposed model is verified by pseudo 1D Buckley-Leverett and Mcwhorter problems. Two test cases, a problem for modeling the secondary recovery of petroleum reservoirs and other one a problem for detecting immiscible contamination are used to show the abilities of shock capturing two phases interface in porous media.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
326
336
http://mme.modares.ac.ir/article_13814_515a6c21a6eaaab1005f14ebb4296c1f.pdf
Dynamic Simulation of the LPRE Turbopump with Considering the Internal Hydraulic Flows of the pump
Mohammad Javad
Montazeri
K.N. Toosi University of Technology
author
Reza
Ebrahimi
عضو هیأت علمی/ دانشگاه صنعتی خواجه نصیرالدین طوسی
author
text
article
2015
per
Dynamic of variation of the hydraulic parameters in the transient operating regime of the liquid propellant rocket engine (LPRE) depends on many factors. In this paper some of these factors such as pump inertia, power balance of pumps with turbine, temperature rise of working fluid in pump passages and variation of pump efficiency with the turbopump rotational speed are simulated. For the first time, filling of the inlet main pipeline and filling of the internal hydraulic channels of pump along with main pump equations are also simulated. To achieve this purpose, governing differential equations of each factor are derived, coupled with each other, and then solved by means of Finite Volume method in Simulink-MATLAB software. Results of this mathematical model are compared with experimental data of a real turbopump and shown that, without considering the internal hydraulic channels of the pump, “ the delay time of the turbopump” is not matched with real results, but by taking the mentioned hydraulic effects into consideration, acceptable agreement would be achieved. Also shown, by changing the resistance and inductance values of internal channels of pump, the settling time of turbopump could be changed, and used as a good factor to optimize the LPRE start process.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
337
345
http://mme.modares.ac.ir/article_13841_cadd0b8cbe10deef31f89dc5e70cc384.pdf
An exact bending solution for functionally graded magneto-electro-elastic plates resting on elastic foundations with considering interfacial imperfections
Naser
Cheraghi
کارشناس ارشد مهندسی سازه
author
Mojtaba
Lazgy Nazargah
عضو هیئت علمی دانشگاه حکیم سبزواری
author
text
article
2015
per
A three-dimensional (3D) Peano series solution is presented for the static analysis of functionally graded (FG) and layered magneto-electro-elastic (MEE) plates resting on elastic foundations with considering imperfect interfacial bonding. The interfacial imperfection is modeled using a generalized spring layer. Regardless of the number of layers, the equations of motion, Gauss’ equations for electrostatics and magnetostatics, the boundary and interface conditions are satisfied exactly. No assumption on deformations, stresses, magnetic and electric field along the thickness direction is introduced. The governing partial differential equations are finally solved using the state-space method. The present formulation has been validated through comparison with other similar works available in the open literature. Effects of two-parameter elastic foundation, gradient index, bonding imperfection, applied mechanical and electrical loads on the static and dynamic response of the functionally graded magneto-electro-elastic (FGMEE) plate are discussed. It is worthy to note that the present novel exact formulation includes all previous solutions, such as piezoelectric, piezomagnetic, purely elastic solution, elastic foundation and interlayer slip problems, as special cases. The obtained exact solution can be used to assess the accuracy of layered FGMEE plate theories and/or validating finite element codes.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
346
356
http://mme.modares.ac.ir/article_13832_165362f375c05f00177e80a2ad7ef222.pdf
Effect of machining and quench-induced residual stress on the distortion
of thin-walled parts
Saeed
Amini
دانشیار دانشکده مهندسی مکانیک، دانشگاه کاشان
author
Soroush
Masoudi
فارغ التحصیل کارشناسی ارشد
author
Ghasem
Amirian
هیئت علمی
author
text
article
2015
per
The main problems in machining of thin-walled parts made of high-strength aluminum alloys are distortion and dimensional instability, which lead to an increase in distorted part scraps and production costs. This article attempts to investigate the correlation between machining-induced and quench-induced residual stresses and the distortion of thin-walled parts made of AL7075 alloy. The experiments are carried out in two steps. In the first step, the effects of polymer and uphill quenching methods in comparison with water quenching in the reduction of residual stresses are investigated on an experimental basis. By conducting the machining tests, the effect of residual stress on distortion is investigated. In the second step, several experiments are carried out under different machining conditions. To study the effect of mechanical and thermal loads on the residual stresses and distortion, the machining force and temperature of cutting area are measured. Finally, the correlation between the machining-induced residual stress and distortion is studied by measurement of stress on some parts. The results indicate that both machining and quench-induced residual stresses are effective in distortion of thin walled parts.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
357
366
http://mme.modares.ac.ir/article_13831_832b6b50ec6135592d41320afe700e13.pdf
Buckling analysis of moderately thick composite conical shells using Galerkin and DQ methods
Mohsen
Hoseini
دانشگاه صنعتی قم
author
Mostafa
Talebitooti
Qom University of Technology
author
text
article
2015
per
The objective of this investigation is to present a semi-analytical method for studying the buckling of the moderately thick composite conical shells under axial compressive load. In order to derive the equilibrium equations of the conical shell, first order shear deformation shell theory is used. The equilibrium equations are derived by applying the principle of minimum potential energy to the energy function that they are in the type of partial differential equations. In the following, the partial differential equations are transformed to algebraic type by using Galerkin and differential quadrature methods and then the standard eigenvalue equation is formed and critical buckling load is calculated. Also, to validate the results obtained in this study, comparisons are made with outcomes of previous literatures and the results of Abaqus finite element software. Analyzing the results, shows the convergence speed and good accuracy of differential quadrature method and desired precision of Galerkin method in calculating the critical buckling load. Finally, the effect of cone angle, fiber orientation, boundary conditions, ratios of thickness to radius and length to radius of the critical buckling load are studied.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
367
375
http://mme.modares.ac.ir/article_13833_e62f4cf4288235924e3d234ed6c84442.pdf
Comparison and Development of multi-phase Pseudo-potential model for various equations of state
Seyed Meysam
Khatoonabadi
ندارم
author
Mahmoud
Ashrafizadeh
عضو هیئت علمی دانشگاه صنعتی اصفهان
author
text
article
2015
per
Numerous models have been proposed to incorporate various equations of state (EOS) into the pseudo potential model. This paper presents an investigation of different EOS types based on the Gong and Cheng model in multiphase-single component flows by the lattice Boltzmann method. Primarily, it is conducted to investigate eight EOS’s classified in four categories; the Shan- Chen EOS, the cubic EOS, the non-cubic EOS, and the cubic and non-cubic combination EOS. The results show that each EOS type results in producing relatively similar spurious currents and has a maximum achievable density ratio. Although by choosing a proper beta parameter for every EOS the simulation errors decrease dramatically, our results show it is impossible to set a constant parameter for the non-cubic EOS. Therefore, a new equation is introduced to predict an efficient beta for the cubic and the Shan- Chen EOS’s. It is also found that the non-cubic, cubic, and non-cubic and cubic combination EOS’s have a wider temperature range and larger density ratios respectively. Hence, we determine a temperature dependent function for the beta parameter prediction instead of using a fixed value for the non-cubic EOS. The results are noticeably in better agreement with those of the Maxwell construction (theoretical results).
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
376
386
http://mme.modares.ac.ir/article_13834_4a5bdb092a0b21cfd86a0d111db74640.pdf
Sound Localization in Glass Plate Using Low Sampling Rate
Seyed Amir
Hoseini Sabzevari
دانشگاه فردوسی مشهد
author
Majid
Moavenian
دانشگاه فردوسی مشهد- دانشکده مهندسی-گروه مهندسی مکانیک
author
text
article
2016
per
In this study the sound localization is implemented to find the impact position on the surface of a glass plate using acoustical sensors. As an experimental example, the sound caused by ping pong ball impact on the glass plate is used. Most of the published paper algorithms are based on using large number of sensor with high sampling rates. In this study a new method is extended due to sound localization. In the proposed method, by reducing the number of sensors into two, a pattern for secondary points is extended. In the specified pattern, locations of points are restricted according to the sensors signal frequency specification. To achieve this goal, a database is gathered from sound caused by ball impact on the glass plate. Furthermore, in order to specify sound localization, space feature based on entropy of wavelet transform coefficient signals from frequency domain of impacts and geometrical specification was extracted. Finally by implementing signal processing into the data the location of impacts are specified. The results show average values of error and Standard deviation 17 centimeter and 1.34, respectively.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
387
393
http://mme.modares.ac.ir/article_13835_0e42df32e2778962ed03e4ab988983c0.pdf
Improving heat performance of rectangular fins
Afshin
Ahmadi Nadooshan
استادیار گروه مکانیک دانشگاه شهرکرد
author
Shekoufeh
Mohammadi
دانشجو
author
text
article
2015
per
This paper studies the numerical analysis of a three dimensional incompressible laminar fluid flow on rectangular fins with circular perforations which stands on a flat surface. Perforations by circle cross sections are scattered on the length of the fin and the number of holes is variable between 1 to 2. The Simple algorithm is the main approach to solve the problem. To the end of discretization of momentum and energy equations, the second order upwind technique has been employed. The Reynolds number is assumed between 100 to 350 concerned to the thickness of the fin. The main contribution of this paper is finding the optimum place of perforations and afterwards compare the thermal performance and Nusselt number of the fins with one and two perforation and solid fin. The results showed the fin with two perforation has the higher thermal performance than both the fin with one perforation and solid fin. The main novelty of this paper is in using circular perforation, as expected, due to the lower weight of fin with two perforation than other mentioned fins it has bigger heat transfer coefficient compared to both others. The advantages of circular perforation can be mention as economical reasons and simpleness of implementation as compared to other developed techniques in the literature.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
394
404
http://mme.modares.ac.ir/article_13836_44ec660d354f49909c8d34f44a9cc562.pdf
Investigation of power law index as a design criterion of statically loaded multilayered functionally graded piezoelectric plate in thermal environments
Bashir
Behjat
دانشگاه صنعتی سهند
author
Hossein
Normohammadi
دانشگاه صنعتی سهند
author
text
article
2015
per
This paper investigates static behavior of multilayered functionally grated piezoelectric plates under thermal loads. The plate with functionally graded piezoelectric material (FGPM) is assumed to be graded through the thickness by a simple power law distribution in terms of the volume fractions of the constituents. Considering the thermal coefficients of piezoelectric material in the constitutive equations (the terms that will couple temperature effects to the piezoelectric properties, named pyroelectric constants) and using the kinematic assumptions of first-order shear plate theory (FSDT), the constitutive equation of FGP plate is written. Then, by using principle of virtual work, the governing equations of a FGP plate is obtained. These equations are solved by finite element method using eight node shell element. Functionally graded piezoelectric plate under static loading, different layers and boundary conditions are considered and results in various thermal loadings have been obtained. Deflection and voltage results for different power law exponent and different boundary conditions are shown. In this paper, the influence of power law index on the static behavior of FGPM plate (including deflection and voltage) under thermal loading is investigated. These responses can be used as a criteria for design of FGP sensors and actuators in the thermal environment.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
405
415
http://mme.modares.ac.ir/article_13837_2885d6dbc2c3c74337a90d1e1448e6ec.pdf
Experimental investigation of the effect of the addition of carbon nanotubes on the quasi-static punch shear penetration of the laminated glass / epoxy composite
Mohammad
Sadeghi
دانشجو کارشناسی ارشد-دانشگاه تفرش
author
Mohammad Hossein
Pol
عضو هیات علمی/دانشگاه تفرش
author
text
article
2015
per
In this paper, the effects of adding carbon nanotubes to quasi-static punch shear properties (QS-PS) and mechanical properties of hybrid laminated composites has been investigated experimentally. The nanocomposites have 12 layers of 2D woven glass fiber with area density of 200g/m2, is manufactured by Hand lay-up method. Epoxy resin systems is made of a diglycidyl ether of bisphenol A (DGEBA), Epon 828, as the epoxy prepolymer and Epikure F-205 as the curing agent. In this study, was used the multi-walled carbon nanotube (MWCNTs) modified with hydroxide (-COOH), with weight fraction 0, 0.1, 0.5 and 1 respect to total weight of resin. Results of tensile test have showed, addition of carbon nanotubes can change tensile properties of matrix. Maximum increase can be seen in modulus of the resin of 0.5% nanotubes content around 31%. Moreover, the results of tensile properties of hybrid laminated nanocomposites show maximum change in toughness of sample of 0.5% nanotube content around 14% with increasing tensile strength and fracture strain. The results punch shear test show that the adding of carbon nanotubes has little effect on total energy absorbed so that maximum increase is around 4% in sample of 0.5 %.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2015
416
424
http://mme.modares.ac.ir/article_13840_14dda6312da384ee0fde94141f1a71b9.pdf
Investigating effect of Norton and Liu – Murakami creep models in determination of creep fracture mechanic parameter (C*)
Soheil
Nakhodchi
عضو هیات علمی/استادیار دانشگاه صنعتی خواجه نصیرالدین طوسی
author
Ehsan
Saberi
دانشجوی کارشناسی ارشد
author
text
article
2016
per
Creep fracture mechanic parameter, C*, is an essential tool for creep crack growth rate estimation and so remnant life determination of components operating at high temperature. For determining this parameter experimental works, FE methods, and engineering approaches can be utilized. In this paper in order to facilitate FE methods in C* determination for a CT specimen, creep behavior models of Norton and Liu-Murakami were developed and related subroutines were created. Each of the aforementioned models has its own temperature dependent material coefficients which were determined and validated based on creep rupture tests on crack free uniaxial specimens of P91 steel and IN718 super alloy respectively in 650˚C and 620˚C temperature. In this study creep fracture mechanic parameter value of a CT specimen made of P91 steel were derived by application of Norton and Liu-Murakami creep behavior models and results were compared with results of the experimental tests and reference stress engineering approach results. The results indicate that Liu-Murakami creep behavior model most exactly estimates creep fracture mechanics parameter, but yet reference stress engineering approach is the most economical way to determine this parameter.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
425
434
http://mme.modares.ac.ir/article_13838_b43be2c0584061a787ad261b0ae02115.pdf
Experimental investigation of Aluminum tubes hot gas forming and production of square cross-section specimens
Mehrdad
Nasrollahzade
دانشجوی دانشگاه تربیت مدرس
author
Hassan
Moslemi Naeini
استاد دانشگاه تربیت مدرس
author
Seyed Jalal
Hashemi
استاد موسسه غیرانتفایی کار قزوین
author
Behnam
Abbaszadeh
دانشجوی دانشگاه تربیت مدرس
author
Javad
Shahbazi Karami
دانشجوی دکتری دانشگاه شهید رجایی
author
text
article
2016
per
In recent years, aluminum, magnesium and titanium alloys are highly regarded in the aerospace and automotive industries due to their high strength to weight ratio and resistance to corrosion. The main problem of the use of these alloys is their low formability at room temperature. To solve this problem, the metal forming process is done at high temperatures. Since oil’s heat resistant temperature is not more than 300°c, other fluids such as air and nitrogen gas should be used in high temperatures. In this study, blow forming equipment at high temperatures has developed, and changing of AL6063 tubes cross-section from circular to square has investigated experimentally and compared with the results of the experiments at room temperature. After producing square products, thickness distribution, corner’s radius, forming pressure, and effect of pressure time in corner’s radius at different temperatures were compared and the location of bursting was also examined. The results indicated that by increasing temperature, formed radius and pressure time reduces significantly, so that the amount of radius decreases from 19.5 mm in the temperature of 25°c and 154 bar forming pressure, to 5.8 mm in the temperature of 500°c at 11 bar forming pressure. The results showed that by increasing time pressure, which causes to decrease velocity of process, the formed corners has been sharper. By investigating burst of specimens, bursting occurs in the area of converting circular cross section to square one, which has a high deformation and tensile strain.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
435
442
http://mme.modares.ac.ir/article_13839_8aa5b1294cd0d54e7c7210ff255dbcb4.pdf
Effect of TiN/TiCN/Al2O3 multilayer coating on Tungsten Carbide drill on drilling process of spherodized cast iron
Fariborz
Jalali
دانشجوی کارشناسی ارشد/دانشگاه شاهرود
author
Mojtaba
Ghatee
هیئت علمی/دانشگاه شاهرود
author
Seyed Majid
Hashemian
هیئت علمی دانشگاه شاهرود
author
text
article
2016
per
Cemented carbides are the most common cutting tool materials. To improve machining process, the surface of the cutting tools must be wear resitance with high hardness and chemical inertness. In recent years, several coatings have been developed for tungsten carbide. In this paper, the effect of TiN/TiCN/Al2O3 multicoatings on the performance of drilling process of spherodized cast iron was studied. The external layer is Al2O3 which has high resitance to wear and TiN was chosen as internal layer because of it excellent adhesion to the tungsten carbide surface. The intermediate layer was TiCN because of its compatibility with the other layers. At first, drills were prepared by machining process and then the triple layer coating was applied on the surface of tungsten carbide drills by chemical vapor deposition method. The coating process was performed under usual industrial condition. The thickness of the coatings was 10 micrometers. The wear of drills, the surface roughness and the hole diameter tolerance were investigated. The structure of coating and wear surface was studied by scanning electron microscopy. It was found that the multiple coating significantly improved the wear resistance of the drill compared to uncoated tolls. In addition, it was found that the surface roughness and hole diameter tolerances improved by drilling with coated tools. The reason of this would be the lower wear rate and resulting dimension stability of the coated tools. In addition, according ot wear surface structure, it was concluded that the mechanism of wear was abrasion.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
443
449
http://mme.modares.ac.ir/article_13842_37bb7bc2469c09526afe140da683bc0b.pdf
Investigation of lubricant effect on depth filling of metallic bipolar plates with concave and convex patterns in rubber pad forming process
Majid
Elyasi
استادیار دانشگاه صنعتی نوشیروانی بابل
author
Farzad
Ahmadi
دانشگاه صنعتی نوشیروانی
author
Morteza
Hosseinzadeh
دانشگاه آمل
author
text
article
2016
per
Rubber pad forming is a practical and low-cost method of producing metal bi-polar plates with complicated multi- array contours since it only needs a rigid die and a flexible rubber. In this study, 316 stainless steel sheets with the thickness of 0.1 mm were used. To form the plates, a polyurethane rubber was used with the hardness shore of A 85 with the thickness of 25 mm. In order to increase the depth of the channel flow and form filling plates with a high depth-to-width ratio, firstly, the effects of lubricants on shaping metal plates were ignored. Subsequently, by implementing lubricants, their effects on achieving a higher filling depth and a more uniform thickness distribution were investigated. The results showed that in rubber pad forming process, lubricants could be used to further enhance the depth of filling and have a uniform thickness distribution in the channels of generated plates. Moreover, among available lubricants, polypropylene nylon will be the best alternative for the production of bipolar plates due to its high tensile strength and low thickness.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
450
460
http://mme.modares.ac.ir/article_13843_f2c849bea33f3666d27558634e0aae2a.pdf
Investigation of dimensional accuracy of metallic bipolar plate's micro channel in rubber pad forming process
Majid
Elyasi
استادیار دانشگاه صنعتی نوشیروانی بابل
author
Hossein
Talebi Ghadikolaee
دانش آموخته کارشناسی ارشد دانشگاه صنعتی دانشگاه نوشیروانی بابل
author
Morteza
Hosseinzadeh
عضو هیات علمی دانشگاه آیت الله آملی
author
text
article
2016
per
Metallic bipolar plate is one of the main parts of fuel cell. Several methods were used by researchers to manufacturing bipolar plate such as stamping, hydroforming and electromagnet forming. The effect of process parameters on dimensional accuracy of metallic bipolar plates in rubber pad forming process has been investigated in this study. ABAQUS/Standard finite element software is used to simulate the process. The accuracy of the results of simulation process is evaluated by using experimental results. To perform experimental procedures, rigid die with parallel flow field is used to form SS316 bipolar plate with 0.1 mm thick. For this purpose the effect of punch load, rubber hardness, rubber thickness and clearance between die and container on the dimensional accuracy of the formed parts is investigated. In this regard, rubber layer with hardness of 55, 70, 85 and 90 Shore A and thickness of 1.5mm up to 5.5mm were used. The result show difference between lateral and central channel depth, the amount of disparity will decrease by increasing in punch load, as a result the dimensional accuracy will increase. According to the result, increase in hardness and thickness of the rubber layer lead to improve the dimensional accuracy. Also considering clearance between die and container decrease the difference between lateral and central channel depth and eventually cause increasing in dimensional accuracy of formed part.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
461
471
http://mme.modares.ac.ir/article_13844_ec44ed0624d05d0972ad65a31986b2f4.pdf
An investigation on the stress concentration factor in unidirectional composite lamina with angled and staggered crack
Saeed
Rahnama
دانشگاه بیرجند
author
Mehdi
maleki
دانشگاه بیرجند
author
text
article
2016
per
In this paper by using of modified shear-lag model and superposition technique, the stress concentration factor in a unidirectional composite lamina with angled and staggered cracks is investigated. Unlike classical shear-lag model, in modified model, both the fiber and matrix are able to sustain axial loads. For a unit cell of fiber and matrix , the differential-difference equations of equilibrium were derived and solved for displacements and stress fields within the lamina. For a total fiber N and row of r, number of break fiber ,by superposition technique, The maximum stress concentration factor of lamina with angled and staggered breaks was calculated. Results show that the classical shear-lag model can not predict the stress concentration factor accurately when value of Matrix-to-Fiber moduli ratio is increased. In glass-epoxy lamina with staggered and angled cracks, the maximum stress concentration factor decreases by 39% and 43%, respectively, versus the aligned fiber breaks. By increasing the Matrix-to-Fiber moduli and Matrix-to-Fiber volume fraction ratios the maximum stress concentration factor decreases. As Em/Ef approaches to zero, results have a good agreement with primary shear-lag model.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
472
480
http://mme.modares.ac.ir/article_13867_6b4a37af3a91a4ce476a38a8c4c726ad.pdf
Determination of optimum diameter of Earth to Air Heat Exchanger by analytical method for air conditioning
Seyed Ali
Mirahmadi Golrodbari
دانشجوی کارشناسی ارشد مهندسی مکانیک تبدیل انرژی دانشگاه تربیت مدرس
author
Mehdi
Maerefat
دانشیار مهندسی مکانیک تبدیل انرژی دانشگاه تربیت مدرس تهران
author
Amin
Haghighi Poshtiri
استادیار مهندسی مکانیک تبدیل انرژِی دانشگاه گیلان (رشت)
author
Asgar
Minaei
دانشجوی دکترا مهندسی مکانیک تبدیل انرژی دانشگاه تربیت مدرس تهران
author
text
article
2016
per
In the present study, a new analytical model for Earth to Air Heat Exchanger is presented. To this end, transient energy equation is solved employing duhamel's theorem and the soil temperature distribution is achieved with the concept of G function. Then, the outlet temperature will be achieved by solving the energy equation along the length of heat exchanger. In comparison to previous models, the present results are in better agreement with those obtained experimentally. Parametric investigation and feasibility study of this system in Tehran has been made using this analytical model for summer season with two different input temperatures. Parametric investigation showed for each mass flow rate, the corresponding optimum diameter is gained. It is observed that optimum diameter is a function of mass flow rate and operation time and independent of soil and input temperature of heat exchanger. For major mass flow rate supply, utilization of heat exchangers with minor mass flow rate is suggested; accordingly the temperature of heat exchanger is decreased. The depth and distance between heat exchangers can be calculated by the present model. It is also revealed this system can solely supply thermal comfort in continuous summer operation for cities with cold climate and low annual average temperature.
Modares Mechanical Engineering
Tarbiat Modares University
1027-5940
15
v.
12
no.
2016
481
490
http://mme.modares.ac.ir/article_13889_6f6c59b4027330dd26ec11d32ec88040.pdf