Ahmad Reza Khoogar; Mohamad Ali Mohades; Khodadad Vahedi
Volume 6, Issue 3 , September 2013
Abstract
In design of defense structures, concrete are often used to provide protection against incidental dynamic loadings such as the impact of a steel projectile. In the present study, a new analytical model is proposed to predict penetration depth into concrete targets by ogive nose projectile. Hence, to ...
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In design of defense structures, concrete are often used to provide protection against incidental dynamic loadings such as the impact of a steel projectile. In the present study, a new analytical model is proposed to predict penetration depth into concrete targets by ogive nose projectile. Hence, to develop the model and simulate penetration of high velocity ogive-shape nose steel projectiles into concrete targets, several tests has been simulated numerically with the Ls-Dyna finite element code. The results show good agreement with the analytical analyses and experimental results from other researchers.
kali Dass
Volume 6, Issue 3 , September 2013
Abstract
This paper presents the findings of experimental investigations into the effects of cutting speed, feed rate, depth of cut and approach angle on the machinability of titanium (Grade-5) alloy. Also the comparison for the two different cutting materials inserts polycrystalline diamond (PCD) and cubic boron ...
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This paper presents the findings of experimental investigations into the effects of cutting speed, feed rate, depth of cut and approach angle on the machinability of titanium (Grade-5) alloy. Also the comparison for the two different cutting materials inserts polycrystalline diamond (PCD) and cubic boron nitride (CBN) with similar tool geometry for similar machining parameters is also carried out. Design of experiment technique i.e. response surface methodology (RSM) has been used to accomplish the objectives of the experimental study. The experimental plan for four factors at three level using face centre, centred composite design (CCD) was employed. The results indicated that the approach angle as a dominant factor on the surface roughness and the tangential force evaluation as machinability criteria .The PCD insert showed that in comparison to CBN cutting inserts have better surface finish and smaller cutting force for the level of parameters considered for investigations in machinability study of Titanium (Grade-5) alloy.
Sadegh Rahmati; Hossein Kheirollahi; Abbas Azari
Volume 6, Issue 3 , September 2013
Abstract
Dental implants restorations basically include four parts: implant, abutment, metal framework, and crown. In this common kind of restoration, crown is cemented to metal framework. However, in this research a novel method of design of dental implant is presented which includes only two components: Integrated ...
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Dental implants restorations basically include four parts: implant, abutment, metal framework, and crown. In this common kind of restoration, crown is cemented to metal framework. However, in this research a novel method of design of dental implant is presented which includes only two components: Integrated implant, and Crown. The new designed is based on an integrated implant which enables dentist to fit the crown by a snap-fit ring instantly. In order to carry out stress analysis, the finite element method (FEM) is applied on implant and bones to verify different loading conditions. The results of FEM are presented and proved to satisfy different loading conditions successfully.
Kasra Karbaschi
Volume 6, Issue 3 , September 2013
Abstract
3D imagination of human's organs has become feasible by digital image processing techniques and algorithms via CT or MRI images in recent years. In this study, a new method for reverse engineering and biomodelling of hard tissues by CATIA cloud points' concept has been considered. Comparing with the ...
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3D imagination of human's organs has become feasible by digital image processing techniques and algorithms via CT or MRI images in recent years. In this study, a new method for reverse engineering and biomodelling of hard tissues by CATIA cloud points' concept has been considered. Comparing with the current softwares (e.g. BioBuild or Mimics) has shown the new method's easiness of implementing and modelling, final model's high accuracy, easiness of data exchanging with the rapid prototyping systems and reduction of need for having anatomical background for interpreting the CT or MRI images.
Mohsen Ghazikhani; Ali Mohammadian; Iman Mirzaii
Volume 6, Issue 3 , September 2013
Abstract
An industrial gas turbine has the characteristic of decreasing output power on hot summer days while electricity demand peaks. Steam injection in gas turbines has been used for many years to prevent the loss of performance of gas turbines caused by high ambient temperature. Vodoley system is a Closed ...
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An industrial gas turbine has the characteristic of decreasing output power on hot summer days while electricity demand peaks. Steam injection in gas turbines has been used for many years to prevent the loss of performance of gas turbines caused by high ambient temperature. Vodoley system is a Closed Steam Injection Gas Turbine Cycle (CSIGTC), which is known as a self-sufficient in steam production. In this study the influence of steam injection in Mashhad Power Plant GE-F5 gas turbine parameters was experimentally investigated. Moreover a computer modelling has been used to study water balance in a CSIGTC system. The results show that although system has additional water treatment process, applying it increases thermal efficiency up to 35.33 percents for 25 MW of power output at an ambient temperature of 40 ˚C. Also water balance considerations show for a direct contact condenser of 96% efficiency and the exhaust temperature of 420 ˚C at turbine outlet, about 7.8 kg/s of make up water is needed under ISO rating of gas turbine (101.3 kPa, 15 ˚C) which must be provided for the CSIGTC system. This amount of water is about 51% of injected steam.
Alireza Hajipour
Volume 6, Issue 3 , September 2013
Abstract
In this paper, the effects of input temperature and compression ratio on the net output work and efficiency of the air standard cycles, i.e. Atkinson cycle, Diesel cycle and Otto cycle are analyzed. We assumed that the compression and power processes are adiabatic and reversible and any convective, conductive ...
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In this paper, the effects of input temperature and compression ratio on the net output work and efficiency of the air standard cycles, i.e. Atkinson cycle, Diesel cycle and Otto cycle are analyzed. We assumed that the compression and power processes are adiabatic and reversible and any convective, conductive and radiative heat transfer to cylinder wall during the heat rejection process may be ignored. We compared efficiency of these cycles with constant maximum temperature of each cycle. The results of this comparison may provide guidance for performance evaluation and improvement of practical internal combustion engines.
Mohammad Zaman Kabir; Ata HojjatKashani
Volume 6, Issue 3 , September 2013
Abstract
The aim of this research is to investigate the effect of Carbon Fiber Reinforced Polymer (CFRP) composite fabric on monotonic and fatigue behaviors of reinforced concrete beams. To control the failure occurrence, a small notch was induced at the middle span in bottom surface for all of the studied RC ...
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The aim of this research is to investigate the effect of Carbon Fiber Reinforced Polymer (CFRP) composite fabric on monotonic and fatigue behaviors of reinforced concrete beams. To control the failure occurrence, a small notch was induced at the middle span in bottom surface for all of the studied RC specimens. Totally 12 beams were tested from which 6 beams tested under monotonic and 6 other tested under fatigue cyclic loading. Every 6 tested beams consisted of 3 intact and 3 CFRP retrofitted RC beams. The specimens were 150×150×1000 mm in dimensions and a 150 mm-deep notch was cut at the center. The experimental examination was conducted to study stresses distributed throughout the critical regions in reinforced concrete and carbon fiber reinforced plastic (CFRP) strengthened RC beams. Fundamentally, these critical regions are cracked zones in CFRP-retrofitted RC beams. Results from monotonic and fatigue tests were compared to each other. In the monotonic test, shear stress distribution and stiffness measurements were carried out until the failure of specimens. In the fatigue test, the ceiling of applied load was considered at the level of design service load for bridges. In addition, strain measurements led to the calculation of interfacial shear stresses between concrete substrate and the CFRP layer. The variation of such stresses through load cycles will be presented and discussed. Load–deflection curves, strain responses and propagation of tension cracks would provide an insight on the performance of the CFRP strengthened beams subjected to different cycles of fatigue loading.
Hamed Sheikhalishahi; Mahmoud Farzin; Reza Jafari Nedoushan; Mohammad Ali Rasouli; Masoud Aliheidar
Volume 6, Issue 3 , September 2013
Abstract
Superplastic materials show huge amount of deformation in low strain rates and temperature above half of melting point. In superplastic forming, estimating the pressure–time diagram and thickness distribution has significant importance. Utilizing numerical methods, the involved parameters in superplastic ...
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Superplastic materials show huge amount of deformation in low strain rates and temperature above half of melting point. In superplastic forming, estimating the pressure–time diagram and thickness distribution has significant importance. Utilizing numerical methods, the involved parameters in superplastic forming can be optimized for such estimations. In the present paper, the simulation of superplastic forming of a cup-shape part is demonstrated, assigning the proper constitutive equation. In the following, a noble approach for estimating the pressure–time diagram, using finite element method, is presented and by using this approach, the optimum pressure–time diagram for the forming process is estimated while the effects of process parameters such as friction index and strain rate on pressure–time diagram and thickness distribution is evaluated. Simulation results are compared with other researches results, which show satisfactory agreement.
Mohammad Sajjad Mahdieh; Ehsan Rafati; Samaneh Kargar Sichani
Volume 6, Issue 3 , September 2013
Abstract
Surface roughness of engineering parts is very significant property that effectively influences on the wear and fatigue strength. There are many methods for improving surface quality of engineering parts such as grinding, lapping and honing. One of the methods for improving surface quality is Roller ...
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Surface roughness of engineering parts is very significant property that effectively influences on the wear and fatigue strength. There are many methods for improving surface quality of engineering parts such as grinding, lapping and honing. One of the methods for improving surface quality is Roller Burnishing. Roller Burnishing improves surface quality of engineering parts by means of Cold working. Roller Burnishing depends on many factors such as RPM of work piece, feed rate of Burnishing tool and the penetration depth of Roller burnishing tool into the work piece. At the present paper, we have tried to investigate the effective factors of Roller Burnishing and optimize them by means of Taguchi approach.
esmail delfani; ahmad delfani; a ghoddosian
Volume 6, Issue 3 , September 2013
Abstract
Nowadays, different methods are used to solve optimization problems which ,one of the newest is BCO method that are inspired by the nature and derived from the social life of bees of these methods can be noted that BCO is derived from the social life of bees. We use in this paper fuzzy logic for bee‟s ...
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Nowadays, different methods are used to solve optimization problems which ,one of the newest is BCO method that are inspired by the nature and derived from the social life of bees of these methods can be noted that BCO is derived from the social life of bees. We use in this paper fuzzy logic for bee‟s decision stage. at the end, we solve two different problem that have already been solved by ESO (Evolution Structural Optimization ) and BESO (Bi direction Evolution Structural Optimization ) methods. In this paper we indicate BCO is able to achieve better solutions and this method is quite proper even for constrained problems.
Ahad Zarghami; Negar Ahmadi
Volume 6, Issue 3 , September 2013
Abstract
A finite volume-lattice Boltzmann algorithm is applied to study skin friction behaviour in different channel flows. For this purpose, cell centred scheme is adapted to discretize the Boltzmann equation and consistent boundary conditions are also addressed, which resulted in a wider domain of stability. ...
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A finite volume-lattice Boltzmann algorithm is applied to study skin friction behaviour in different channel flows. For this purpose, cell centred scheme is adapted to discretize the Boltzmann equation and consistent boundary conditions are also addressed, which resulted in a wider domain of stability. A simulation of flow in a two dimensional channels with different geometries are carried out. The results are compared with the valid previous results in which favourable agreement was observed. The results showed that skin friction in plane Poiseuille flow converged to 24/Re, but skin friction distribution in suddenly enlarged channels regain symmetry after some distance downstream of the expansion plane.
Adel Gholami; Arman Fathi
Volume 6, Issue 3 , September 2013
Abstract
Abstract: Implementing a combined cooling, heating and power system(CCHP) to cool, heat and produce electricity is growing rapidly due to its efficiency and low emissions. In this paper, using economic analysis, the size and operation detail of the required gas engine and the specific electricity, cooling ...
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Abstract: Implementing a combined cooling, heating and power system(CCHP) to cool, heat and produce electricity is growing rapidly due to its efficiency and low emissions. In this paper, using economic analysis, the size and operation detail of the required gas engine and the specific electricity, cooling and heating load curves for a one year operating period has been determined. The proposed CCHP system meets thermal demands of the facility and has been evaluated under such strategy. Net Annual Profit (NAP) has been introduced as an objective function to be maximized through a developed nonlinear mixed integer programming software. The operation strategy and the payback period of the chosen system have also been determined. A study with the purpose of including or excluding subsidy prices has been carried out. Furthermore, a sensitivity analysis was elaborated in order to show the dependency of optimal solutions to some key contributing factors such as fuel price, electricity buying price and electricity selling price. Results show that, these parameters have significant effect on the system’s performance.