Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
Heat Exchangers in A C3MR LNG Plant, Cooling Curves and Their Effects on Efficiency
EN
Hamid
Safari
saffari@iust.ac.ir
Masoud
Fasihbeygi
masoudfbeiki@gmail.com
In this paper, we are going to improve the energy efficiency of an industrial C3MR base load LNG plant by changing its refrigerant components and its mole fractions in liquefaction and subcooling cycles based on the cooling curves generated in the main liquefaction and subcooling heat exchangers. Later on, selection features of the elements will be discussed. First, non-optimized C3MR plant models and the obtained cooling curves reveals. The process is modeled by using the Hysys® software. The PRSV equation of state is used for thermodynamics properties calculations both for the natural gas and the refrigerants. Two methods for modeling and optimization are explained and the results are compared. The first optimization method is done by a try and error method, which uses temperature vs. enthalpy diagrams or thermodynamics second law (Exergy loss). This method is based on decreasing the temperature difference between hot and cold streams. In the second method, optimizer of Hysys® is used. In this method, a random mole fraction suggests by optimizer at each step and the plant’s consumption work calculates. By comparing the obtained consumption’works and choosing the least one, the relative mole fractions determines as the optimized refrigerants. The convergence of results of method 1 and 2 (The mole fractions of liquefaction and subcooling refrigerants) proves the accuracy of these methods and the models and primary predictions. The results show that by optimization of mixed refrigerants, it is possible to decrease the energy demand about 10.4 MW (5.36 %).
http://admt.iaumajlesi.ac.ir/article_534723.html
http://admt.iaumajlesi.ac.ir/article_534723_eea3fcca71dfbac3b0a268c46ccc6363.pdf
Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
Numerical Analysis of Rectangular Isotropic and Orthotropic Thin Plates Based on the Radial Point Interpolation Method (RPIM)
EN
MohamadMehdi
Najafzadeh
m-najafizadeh@iau-arak.ac.ir
Majid
Alavi
ma33@gmail.com
AliReza
Nezam Abadi
ana33@gmail.com
Mohsen
Kogani
mk33@gmail.com
In the recent paper, one of the numerical methods without element, for static analysis of thin plates displacement based on classical plates theory (CPT), has been presented. In this method, the domain of problem solving is shown only by the means of a set of nodes, and there is no need to any mesh scheme or element. One of the kinds of element free methods used here is the Radial Point Interpolation Method (RPIM). In order to access to the governing equations, the Hamilton principle is used in the form of Galerkin weak form. Using interpolating functions, the field variables, namely the displacement, are approximated, and by applying the governing equations, the convergence and the accuracy of the present method are studied. Results of the present method are compared with the results of the exact solution of analytical methods of plates and also with the finite element method (FEM). In addition, the effects of thickness ratio to length, appearance coefficient, and node distribution are discussed.
http://admt.iaumajlesi.ac.ir/article_534724.html
http://admt.iaumajlesi.ac.ir/article_534724_8d2f1832765f538465ddf558c1eeff21.pdf
Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
Analysis of the Dynamical Behavior of the Delay Mechanism in a Projectile Motion Controller, Using 3D Finite Element Simulation
EN
Salman
Naderi
sajad1378@gmail.com
Mehdi
SalmaniTehrani
tehrani-m@eng.sku.ac.ir
Kourosh
Hasanpour
kourosh_hasanpur@yahoo.com
In this paper, dynamical behavior of the delay mechanism of a special projectile controller is studied, using 3D finite element simulation. The controller considered here is among of high-acceleration mechanical controllers. Due to high linear and angular accelerations of the projectile and also explosion risk, experimental investigation is very limited and almost impossible. So, numerical simulation is a valuable tool for designing of this kind of controllers. In the simulations here, the metal coil and its ring belt are the deformable parts of the model, while other parts are assumed to be rigid. Plastic deformation of these deformable parts, during the projectile motion, has a very important effect on the proper operating of the controller. To study the effect of coil material properties, a bilinear stress-strain curve with different yield stress was assumed. The simulation results show that there is an optimum yield stress for the metal coil, by which the appropriate operation of controller may be reached. For the special controller considered here, this optimum yield stress is about 285(MPa). All simulations made use of ABAQUS commercial software.
http://admt.iaumajlesi.ac.ir/article_534725.html
http://admt.iaumajlesi.ac.ir/article_534725_0a8a6e08db5c18590fcfa124250142b8.pdf
Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
The Finite Element Method and Genetic Algorithm Approaches on Shape Optimization of Prosthesis According to Fatigue Behavior
EN
Ramin
Meshabadi
r-meshkabadi@iau-ahar.ac.ir
Sayad
Haji Mohamadi
mohamadi.sayad@yahoo.com
Amir
Kazemi
amir_kazemi81@yahoo.com
The Finite Element Method (FEM) is one of advanced methods in modeling of solid mechanics used in the design and analyzing of prosthesis in the human body. One of the important factors in designing a femur (the linkage between basin and knee) which is under complicated stresses is to minimize the amount of the stress in the components of the prosthesis due to the body weight. In this research the authors have used prosthesis of two different substances to investigate the affect of the materials in the fatigue analyze. The other important factor is to apply a suitable linkage between prosthesis and bone called cement in order to prevent the slip of stem shape in the femur. In finite element analyze we have used contact elements for modeling the surfaces in contact. For the contact surface of stem shape and femur we have considered three cases: Bonded, slippage with the coefficient of friction 0, 0.22. We have used Genetic Algorithms (GA) method to optimize the shape of prosthesis. The results have been compared with the results presented by Charnley which shows an improvement in the shape of prosthesis. The optimized angle is about 132 degrees.
http://admt.iaumajlesi.ac.ir/article_534726.html
http://admt.iaumajlesi.ac.ir/article_534726_6517d2000ff49a08ac5bbd5c28c22280.pdf
Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
Parametric Analysis of Square Thin Walled Section in Energy Absorption due to Oblique Load
EN
Reza
Mohamadipour
rmohamadipoor@gmail.com
Khodadad
Vahedi
khv33@gmail.com
Sayed MohamadReza
Emam
smre33@gmail.com
In this study, first energy absorption of axial and bending loading is considered. Next, thin walled structures under oblique loading are investigated using ABAQUS computer simulation, where 180 different cases are simulated. Simulation results of the thin walled structures under oblique loading were compared with the experimental results of Nagel, and good agreement was perceived. Simulation results revealed that, the amount of energy absorption for thin walled structures is reducing with collision angle. Moreover, the energy absorption performance of thin walled structures can be controlled by geometric parameters; in particular, thickness as one of the most effective parameters in controlling the amount of energy absorption must be considered.
http://admt.iaumajlesi.ac.ir/article_534727.html
http://admt.iaumajlesi.ac.ir/article_534727_bb4f3269e64dded7e48096e845688d9f.pdf
Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
2D Model of Floor Surface Roughness in Micro Milling Operation
EN
Shahriyar
Kournavand
shk33@gmail.com
Behnam
Motakef Imani
imani@um.ac.ir
The micro milling operation is one of the manufacturing processes, which can produce 3D parts in the range of less than a millimetre. Miniaturization of components results in increasing the ratio of surface area to volume of components, which in turn increases the role of surface on the component performance. Therefore, anticipating the relationship between micro milling parameters and surface roughness is of extreme importance. In this paper, a model is proposed which combines the geometric profile of tool end and coordinates of the major cutting edge, which is able to anticipate the profile and surface roughness of the groove floor. The micro-end-mill geometry is considered in macro and micro scales. Relationship between the major cutting edge coordinates and tool profile are derived. Introducing different cutting mechanisms in micro milling operation, effect of different factors such as elastic recovery, and minimum chip thickness, are considered for calculating surface roughness. Feed effect, end edge radius, and effect of minimum chip thickness on surface roughness are investigated for Stainless Steel 316 using the performed simulation of MATLAB software. Moreover, micromilling operation results of the proposed model were compared with experimental results, and correctness of the simulation was validated. In addition, effects of feed per tooth on surface roughness and chip formation were also investigated.
http://admt.iaumajlesi.ac.ir/article_534728.html
http://admt.iaumajlesi.ac.ir/article_534728_89d4122496686d6186e23463839091d6.pdf
Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
Study of the Effect of Lubricant Emulsion Percentage and Tool Material on Surface Roughness in Machining of EN AC 48000 Alloy
EN
Esmaeil
Soltani
es_soltani@iaun.ac.ir
Hessam
Shahali
hsh33@gmail.com
EN-AC 48000 aluminum alloy is an important alloy in industries. Machining of this alloy is of vital importance due to built-up edge and tool wear. Three type of cutting tools including coated carbide (CD1810), uncoated carbide (H10), and polycrystalline diamond (CD10) have been used in this research In This Paper, the effect of machining parameters including lubricant emulsion percentage and tool material on surface roughness has been studied in machining process of EN-AC 48000 aluminum alloy. A L9 Taguchi standard orthogonal arrey has been applied as experimental design to investigate the effect of the factors and their interaction. Nine machining tests have been accomplished with three random repetitions, resulting in twenty seven experiments. Emulsion percentage of lubricant is selected in three levels including 3% , 5% and 10%. Statistical analysis has been employed to study the effect of factors and their interactions using ANOVA method. Moreover, optimal factors level has been presented through signal to noise ratio (S/N) analysis . Also, a regression model has been provided to predict the surface roughness. Finally, the result of the confirmation tests have been presented to verify the adequacy of the predictive model. In this research, surface quality was improved about more than 9% by using lubricant and statistical optimization method.
http://admt.iaumajlesi.ac.ir/article_534729.html
http://admt.iaumajlesi.ac.ir/article_534729_f19d64ebe0b57a75f3c9867da82cdb82.pdf
Islamic Azad University Majlesi Branch
ADMT Journal
2252-0406
2383-4447
3
3
2010
06
01
Creep and Creep-Rupture Characteristics of Lead and Sn70%-30% Lead Alloy
EN
Esmaeil
Barzekar
e.barzkar@me.iut.ac.ir
MohamadReza
Forouzan
forouzan@cc.iut.ac.ir
Materials exhibit significant creep behavior at temperatures above 40% of their absolute melt temperature. Lead, tin and their alloys are such materials which experience significant creep behavior in room temperature. One of the most important applications of the tin-lead alloys is soldering electronic circuits in electronic industry, and for lead are isolation walls and wet batteries. Room temperature for lead is about 50% and for tin70%-lead30% is about 63% of their absolute melting temperature, and considering creep damage during their structural design is of prime importance. In this paper, creep and creep rupture data of these two materials are investigated experimentally. Diagrams obtained from experiment in the applied form, are presented for the application in computer simulation and forecasting connections life cycle. Creep rupture diagrams in the form of time hardening in the creep primary stage are presented to give strain-time relation and Larson-miller and Monkam-Grant parameters. The steady state creep rate relation for both materials in terms of stress function is also provided.
http://admt.iaumajlesi.ac.ir/article_534730.html
http://admt.iaumajlesi.ac.ir/article_534730_41d1823be0046a1d943669d9b817b80f.pdf