2011
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Simultaneous Allocation Of Reliability & Redundancy Using Minimum Total Cost Of Ownership Approach
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This paper addresses the mixed integer reliability redundancy allocation problems to determine simultaneous allocation of optimal reliability and redundancy level of components based on three objective goals. System engineering principles suggest that the best design is the design that maximizes the system operational effectiveness and at the same time minimizes the total cost of ownership (TCO). To evaluate the performance of the TCO allocation numerical experiments were conducted and compared with previous for the series system, the seriesparallel system, the complex (bridge) system and the over speed protection system. From the results of the numerical investigation, reliability redundancy allocation based on minimum TCO will lead to a more reliable, economical design for the manufacturer as well as user compared with the initial cost optimum design and conventional reliability optimum design.
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G.
Kanagaraj
Department of Mechanical Engineering, Thiagarajar College of Engineering, Madurai, Tamil Nadu, India, 625015
Department of Mechanical Engineering, Thiagarajar
Iran
gkmech@tce.edu


N.
Jawahar
Depaertment of Mechanical Engineering and Dean (R&D) Thiagarajar College of Engineering, Madurai, Tamil Nadu, India, 625015
Depaertment of Mechanical Engineering and
Iran
Reliability and redundancy allocation
Mixed integer nonlinear programming
Total cost of ownership
DYNAMIC SIMULATION OF A HIGH PRESSURE REGULATOR
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In this paper, the dynamic simulation for a high pressure regulator is performed to obtain the regulator behavior. To analyze the regulator performance, the equation of motion for inner parts, the continuity equation for diverse chambers and the equation for mass flow rate were derived. Because of nonlinearity and coupling, these equations are solved using numerical methods and the results are presented. Additionally, the dynamic analysis results consist of the output pressure change versus time, the displacement of the moving parts versus time, the regulator mass flow rate versus time and the output pressure versus mass flow rate in different controlling spring preloads. Furthermore, the sensitivity analysis is carried out and the main parameters affecting the regulator performance are identified. Finally, the results of the dynamic simulation are validated by comparing them with the experimental results.
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A. R.
Shahani*
Department of Applied Mechanics, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Pardis Street, Mollasadra Avenue, Vanak Square, P.O. Box 193951999, Tehran, Iran
Department of Applied Mechanics, Faculty
Iran


H.
Esmaili
Department of Applied Mechanics, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Pardis Street, Mollasadra Avenue, Vanak Square, P.O. Box 193951999, Tehran, Iran
Department of Applied Mechanics, Faculty
Iran


A.
Aryaei
Department of Applied Mechanics, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Pardis Street, Mollasadra Avenue, Vanak Square, P.O. Box 193951999, Tehran, Iran
Department of Applied Mechanics, Faculty
Iran


S.
Mohammadi
Department of Applied Mechanics, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Pardis Street, Mollasadra Avenue, Vanak Square, P.O. Box 193951999, Tehran, Iran
Department of Applied Mechanics, Faculty
Iran


M.
Najar
Department of Applied Mechanics, Faculty of Mechanical Engineering, K. N. Toosi University of Technology, Pardis Street, Mollasadra Avenue, Vanak Square, P.O. Box 193951999, Tehran, Iran
Department of Applied Mechanics, Faculty
Iran
High pressure regulator
Dynamic analysis
Nonlinear analysis
Numerical method
VARIATIONAL DISCRETIZATION AND MIXED METHODS FOR SEMILINEAR PARABOLIC OPTIMAL CONTROL PROBLEMS WITH INTEGRAL CONSTRAINT
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The aim of this work is to investigate the variational discretization and mixed finite element methods for optimal control problem governed by semi linear parabolic equations with integral constraint. The state and costate are approximated by the lowest order RaviartThomas mixed finite element spaces and the control is not discreted. Optimal error estimates in L2 are established for the state and the control variable. As a result, it can be proved that the discrete solutions possess the convergence property of order. Finally, a numerical example is presented which confirms the theoretical results.
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Zuliang
Lu*
School of Mathematics and Statistics, Chongqing Three Gorges University, Chongqing 404000, P.R.China;
College of Civil Engineering and Mechanics, Xiangtan University, Xiangtan 411105, P.R.China
School of Mathematics and Statistics, Chongqing
Iran
Priori error estimates
Parabolic optimal control
Integral constraint
Mixed finite element method
Variational discretization
FINITE ELEMENT PREDICTION OF DUCTILE FRACTURE IN AUTOMOTIVE PANEL FORMING: COMPARISON BETWEEN FLD AND LEMAITRE DAMAGE MODELS
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In sheet metal forming processes with complex strain paths, a part is subjected to large plastic deformation. This severe plastic deformation leads to high plastic strain localization zones and subsequent accumulation of those strains. Then internal and superficial microdefects and in other words ductile damage is created. This damage causes quality problems such as fracture. Therefore, design engineers need to accurately estimate the damage initiation and its growth. In this paper, initiation and evolution of damage has been predicted using Lemaitre’s damage and forming limit diagram (FLD) damage models for automotive panel forming, because of its nonlinear strain paths. Lemaitre’s damage criterion has been implemented as a subroutine for an elasticplastic material and plane stress and finite strain theories. Using this subroutine in explicit finite element code, damage initiation and evolution is predicted for the above mentioned process and the results obtained by FLD and Lemaitre models are compared. In this paper, FLD and Lemaitre damage models results show the fact that the damage localization zones are corresponding to the equivalent plastic strain distributions. Comparison of the FLD damage and Lemaitre damage results show that in an automotive panel forming process, both models predict initiation of cracks in the edges of a sheet. Hence, it is concluded that finite element method combined with continuum damage mechanics can be used as a reliable and rapid tool to predict damage evolution in sheet metal forming processes with nonlinear and complex strain paths such as automotive panel forming.
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: Prediction of damage evolution
FLD damage
Lemaitre damage
Automotive panel forming
Nonlinear strain paths
EXPERIMENTAL AND NUMERICAL INVESTIGATION ON LASER BENDING PROCESS
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Laser bending is an advanced process in sheet metal forming in which a laser heat source is used to shape the metal sheet. In this paper, temperature distribution in a mild steel sheet metal is investigated numerically and experimentally. Laser heat source is applied through curved paths in square sheet metal parts. Finite element (FE) simulation is performed with the ABAQUS/CAE standard software package. Material property of AISI 1010 is used in FE model and experiments. The aim of this study is to identify the response related to deformation and characterize the effect of laser power with respect to the bending angle for a square sheet part. An experimental setup including a Nd:YAG laser Model IQL10 with maximum mean laser power of 500 W is used for the experiments to verify FE analysis results. It is observed that numerical results are relatively in good agreement with the experimental results. Results also show that increasing laser power increases the bending angle.
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Laser Forming
Temperature distribution
Finite element method
COORDINATE INFLUENCE ON SINGULARITY OF A 3UPS PARALLEL MANIPULATOR
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This paper shows the coordinates influence on singularity of a three degreeoffreedom structure, namely, threeUniversalPrismaticSpherical (3UPS) parallel manipulator. Rotational coordinates, which are chosen to define the orientation of the platform, affect the singularity of the manipulator. Euler parameters, which don't have any inherent geometrical singularity are utilized, however they are dependent coordinates. This paper shows the advantage of Euler parameters rather than Euler angles as the rotational coordinates for the manipulator. Additionally, the real loci of singularity for the manipulator due to its structure are predicted.
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Singularity analysis
3UPS
Euler parameters
EFFECT OF BOUNDARY CONDITIONS ON LOCALIZED INSTABILITY OF THE SEMIINFINITE ORTHOTROPIC PLATE
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This paper is concerned with an investigation into the localized instability of a thin elastic orthotropic semiinfinite plate. In this study, a semiinfinite plate, simply supported on two edges and under different boundary conditions of clamped, hinged, sliding contact and free on the other edge, is studied. A mathematical model is used and a general solution is presented. The conditions under which localized solutions exist are investigated.
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: Boundary conditions
Instability
Orthotropic plate