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International Review of Mechanical Engineering - July 2009 - Papers

 

   

 

 

International Review of Mechanical Engineering - Papers

 

go to top   Numerical Simulation of Turbulent Forced Convection in Solar Collector Provided with Thickness Baffles and Fins
        by R. Saim, S. Abboudi, B. Benyoucef

        Vol. 3. n. 4, pp. 373-381

 

Abstract - A numerical analysis was carried out to study the thermal performances of a solar air collector with rectangular plate fins absorber and baffles which are arranged on the bottom and top channel walls in a periodically staggered way. This technique is used to increase the heat transfer coefficient between the fluid (air) and the absorber in the solar collector; such as the fixation of baffles and fins to the absorber. To this end we solved numerically, by the finite volumes method, the equations of conservation, of the mass, the momentum and energy. The low Reynolds number k-ε model was adopted for the taking into account of turbulence. The velocity and pressure terms of momentum equations are solved by SIMPLE algorithm.
The parameters studied include the entrance mass flow rate of air. The influence of mass flow rate of air, the collector aspect ratio on the axial velocity and the efficiency of upward type baffled solar air heaters have been investigated numerically. The results show that the flow and heat transfer characteristics are strongly dependent on mass-flow rate of air and the geometry of the baffles. It was observed that increasing the two parameters (blockage ratio and Reynolds number) will increase the Nusselt number, as expected.

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Keywords: Baffle, Solar collector, Turbulent flow, Fins, Conjugate heat transfer.

 


 

go to top   Reliability-Based Optimal Design of Water Distribution Networks under Steady and Transient Conditions
 
        by Berge O. Djebedjian

         Vol. 3. n. 4, pp. 382-395

 

Abstract -  The problem of water distribution system under steady and transient conditions is formulated in this study as an optimization problem under hydraulic reliability. The hydraulic reliability is the probability that a water distribution system can supply consumers’ demands over a specified time interval under specified conditions. The chance constraints formulation is used for the evaluation of the network hydraulic reliability. The approach integrates a genetic algorithm (GA) as an optimization tool, Newton-Raphson as a hydraulic analysis solver, a transient analysis program combined with chance constraint model to evaluate the network reliability. The approach was applied on a network for both steady state and transient conditions. The latter was introduced to the water system by pump power failure and sudden valve closure. The single objective is to minimize the pipe cost for a predefined nodal pressure heads requirements and prescribed level of uncertainty. The application of approach to the case study shows the capability of the chance constraints and the genetic algorithm to find the optimal pipe diameters. This reliability-based optimization technique is an important tool for design and operation of water networks without using hydraulic devices for water hammer control.

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Keywords: Water Distribution Systems, Genetic Algorithms, Optimization, Chance Constraints, Reliability.

 


 

go to top   Modeling Of The Turbulent Transport Of The Passive Scalars In The Heated Cylinder Flow Wake
 
        by T. F. Oda

         Vol. 3. n. 4, pp. 396-409

 

Abstract - The modeling of heat flux transport past a heated 2-D cylinder flow wake contributes to the design of cross flow heat exchanger. The improvement of the performance characteristics of heat exchanger used for chemical industrial purposes, the nuclear reactors, the re boilers ,and the gas turbines will be burden on the discrete evaluation of the heat flux throughout the cylinder flow wake. The study of the turbulent transport of the passive scalars will be helpful in assessing the distribution of temperature ,humidity, pollutant and other chemical species throughout the flow field. A new turbulence model by T. F. Oda was invoked for the numerical solution of the transport equation of the passive scalars. The model extracts an individual transport equation for the Reynolds stress component from the generation- destruction terms of the momentum equations. The other Reynolds stresses components , will be extracted from handling of the pressure gradient equations. The present work will handle the transport equation of the passive scalars using the gained values of velocity components as well as the Reynolds stresses components from the solution of the momentum equations for flow past a circular cylinder. The numerical solutions based on the SIMPLER algorithm of Patankar and Spalding [2,3,4 ] were used to represent the distribution of the passive scalar quantities through the wake of a heated cylinder. The turbulent energy cascade along the cylinder flow wake will be studied. A new dimensionless number called RTN Number [1 ]will be presented as a parameter of turbulent energy transport will be related to the distribution of the heat flux along the heated cylinder flow wake.

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Keywords: Turbulent flow, Heat Transfer, Cylinder flow wake, Transport of passive scalars.

 


 

go to top   Effects of Incorporated Heat Exchangers on the Thermo Economic Analysis of a Water/LiBr Absorption Refrigeration System
Part II: Applications

 
        by I. Boukholda, S. Elmay, A. Bellagi

         Vol. 3. n. 4, pp. 410-416

 

Abstract - This paper is the second part of a thermo-economic analysis of an absorption refrigeration system, ARS. It presents an application of the methodology presented in the first par to three configurations of water bromide ARS. The economic costs of all internal flows and products in each configuration case are calculated, the impact of the heat exchangers efficiency as well as the operating conditions on the thermoeconomic efficiency is analyzed. The results show that the performances obtained when the system operates with only a solution heat exchanger (RHX) is very close to those obtained both the RHX and the solution heat exchanger (SHX) are incorporated in the machine. A similar result is obtained for the costs of all” fuels” and” products” in the system: they are more influenced by the use of the SHX than the RHX.

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Keywords: Absorption, Refrigeration, Exergy, Economic analysis, Water/Lithium Bromide.

 


 

go to top   A Dynamic Substructural Simulation Using Finite Element Analysis By Mapping the Deformation from Structure to Substructure
         by R. Amid, K. Behdinan, D. Metzger, H. Ghaemi

         Vol. 3. n. 4, pp. 417-426

 

Abstract - Generally, Mechanical systems, such as cars, are comprised of various subsystems. These subsystems have specific functional purpose and collectively contribute to the overall performance of the system. The behavior of the isolated subsystem (substructure) subjected to dynamic loading is different than the behavior of the same substructure within the system (structure). This is caused primarily by the boundary conditions imposed on the substructure from the surrounding subsystem. This work presents on the development of a technique for performing substructure analysis on isolated substructures using finite element Analysis (FEA). Here we propose an approach in substructural testing that produces similar results between a substructure in isolation and a substructure in situ using FEA. The developed technique is based on enforcing the mode shapes around the boundary of the substructure in the full structure (referred to as sub-full) onto the boundary of isolated substructure. This is achieved by providing a consistent adjustment to the loading conditions to account for the loss of restraint at the interface with the full structure. The advantage of the proposed techniques is that it lends itself to experimental work.
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Keywords: Structural impact, Substructures, Finite element, Crashworthiness.

 


 

go to top   Finite Element Simulation of an AA2024-T3 Friction Stir Weld
         by J. Gagner, A. Ahadi

         Vol. 3. n. 4, pp. 427-435

 

Abstract - This paper presents a three-dimensional sequentially coupled thermo-mechanical analysis of the friction stir welding process suitable for residual stress prediction. A friction stir butt weld of the aluminium alloy 2024 T3 is simulated using finite element analysis. The thermal model includes diffusive heat transfer in the work pieces and that backing plate, convective heat transfer in the work pieces caused by the material flow, heat generation at the tool, heat loss to the ambient air and heat transfer between the work pieces and the backing plate. The mechanical model includes thermal expansion and tool forces acting on the work pieces. The thermal part of the simulation shows encouraging results concerning the capability to accurately simulate the temperature distribution. The simulated temperatures correspond well to experimentally measured temperatures and the non-symmetric temperature distribution due to material flow is accurately captured in the simulation.
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Keywords: Friction Stir Welding, Simulation, Finite elements, Mass flow.

 


 

go to top   Dynamic Buckling Analysis of Thin Shells Using a Drilling Finite Element
         by B. Labbaci, M. Djermane, F. Hammadi

        Vol. 3. n. 4, pp. 436-441

 

Abstract - The mixed degenerate shell finite element DDSE, incorporating drilling degrees of freedom, is dedicated to solve some engineering applications directly and without any numerical tricks. This finite element has shown good performances in the linear and nonlinear, isotropic and anisotropic, static problems. Thanks to the application of shear and membrane substituted strain fields; it is also free from any locking. The very satisfactory results obtained by its previous application to the nonlinear dynamic regime have suggested the present work. The formulation of the problem, the derivation of the time integration scheme and the mass matrix were conducted in the most appropriate way to deal with the dynamic buckling load prediction. Both geometrical and material nonlinearities are considered in this study.
The general stability criterion of Budiansky-Ruth is used, together with the phase plane control to detect the critical dynamic buckling load. In order to evaluate the accuracy of the element and the effect of the plasticity on the critical dynamic buckling value, two selected and documented examples of the critical dynamic buckling load determination were treated
.
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Keywords: Dynamic buckling, Plasticity, Shells, Finite element, Drilling dof.

 


 

go to top   Complementary Work and the Force Method in the Analysis of Plates and Shells

         by Lazarus Teneketzis Tenek

        Vol. 3. n. 4, pp. 442-450

 

Abstract - Complementary Work and the Force Method are developed for the analysis of plates and shells. A quadrilateral element is conceived with 4 nodes and nodal unknowns the 3 forces and 3 moments in a global coordinate system. A stress plate and shell theory is developed based on variational arguments which yields in its discrete form the global nodal forces and moments. The Force matrix of the element is established and force equilibrium postulated. The theory accepts applied displacements and rotations but applied loads or moments can be inserted as boundary conditions. The solution of the linear system of equations provide the internal loads. After solution, the displacement/rotation field can be estimated on an element basis. Numerical examples on a membrane specimen and plates and shells are provided.

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Keywords: Complementary Work, Force Method EFM, Quadrilateral element, Force matrix, Plates/shells.

 


 

go to top   Effect of the Superficial Hardening on Distortion and Stress State Application on Bearing Race

         by Mounir Kchaou, Mahmoud Yaakoub, Fakhreddine Dammak

        Vol. 3. n. 4, pp. 451-455

 

Abstract - In inductive superficial hardening, the heating delimits the hardened zone while the control of cooling makes it possible to reduce considerably the distortions. The distortions due to the important gradients and those due to the change of the phase are studied. The most important distortions are produced by a nonsimultaneous cooling of different sections of the quenched layer. This unsynchronism of thermal kinetic generates a martensitic growth which is responsible of the complementary deformations. These transformations are sources of residual stress variations along of the hardened zone.
 In this paper, we focus on the stress/thermal interaction modeling. First, we present the results of simulations on cylindrical piece and we show the effect of hardening process on both strains and stresses. Then, we propose to study the effect of the geometry and the initial structure, in order to determine the resulting deformations and how to remedy it. Finally, we show by working the design of the layer, the minimization of the distortions due to the cooling heterogeneity
.

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Keywords: Distortion, Stress, Superficial quenching, Simulation, Bearing race.

 


 

go to top   Failure of Natural Fibre and Hybrid Composites Under Localised Explosive Blast

         by Paul M. Wambua, Rajesh Anandjiwala

        Vol. 3. n. 4, pp. 456-460

 

Abstract - This paper investigates the response of natural fibre and hybrid composites to localised blast loading. Woven glass, carbon, cotton, flax/cotton and flax/cotton/glass hybrid fabric layers were bonded to each other with a polypropylene matrix. Square composite samples were rigidly clamped in a ballistic pendulum and subjected to localised uniform explosive blast using small amounts of PE4 explosives. The test results showed that the dominant failure mode was fibre fracture, delamination and bulging, with several samples exhibiting failure by formation of a complete hole at higher impulses. The glass composites withstood the highest impulses without rupture, followed by the carbon composites.

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Keywords: Blast, Explosives, Biofibres, Hybrid, Composites.

 


 

go to top   Fatigue Simulation of Elastomeric Materials

         by Aidy Ali, A. B. Sanuddin, C. W. Chieh, Reza Afshar

         Vol. 3. n. 4, pp. 461-466

 

Abstract - The paper presents the simulation work on the elastomer subjected to the strain controlled cyclic loads. A three-dimensional finite element model of elastomer specimen which in accordance with ASTM D412 has been developed using CATIA and ANSYS commercial finite element (FEM) packages. The fatigue life predicted from simulation was compared with a well documented published data and show slight disagreement. The simulated strain-life results are slightly lower than the experimental data. Several factors that potentially influenced the variation of the results were noted. Finally, some recommendations have been made at the end of this study to further improve the simulation.

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Keywords: Elastomer, FEM, Strain controlled loading, CATIA, ANSYS.

 


 

go to top   Performance of the Chaboche Kinematic Hardening Model to Predict Ratchet Using Different Data Bases
         by Lynda Djimli, Salim Meziani

         Vol. 3. n. 4, pp. 467-472

 

Abstract - The performance of the Chaboche kinematic hardening model has been evaluated in this paper to predict the ratcheting responses for a broad set of uniaxial and biaxial loading histories. The investigations have been performed with reference to both uniaxial and biaxial experimental data, (a) strain and stress controlled uniaxial tests on tensile specimens; (b) biaxial tests. The parameters of the Chaboche model have been calculated from the uniaxial strain controlled test and then optimized using different data bases. Amongst the various parameters in the Chaboche model, it has been found that the optimized parameters play a crucial role in achieving better simulation. The Chaboche model was observed to predict ratchet on uniaxial loading, the model closely simulated the experimental results. The same parameters have been used to analyze the biaxial loading condition; ratchet has been over predicted by the model. In a general way ratcheting simulation studies by the Chaboche model have resulted in reasonably good agreement with experiments.

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Keywords: Ratchet, Kinematics hardening, Uniaxial and biaxial loading, Strain and stress controlled tests.

 


 

go to top   Modeling of Delamination in Woven Composites Based on a Unit Cell

         by M. R. Khoshravan, F. Azimpoor

        Vol. 3. n. 4, pp. 473-780

 

Abstract - The aim of this paper is to provide modeling and numerical analysis of delamination for increasingly complex woven reinforced composite materials. Modeling of the woven reinforced composite materials due to the existence of the weft and woof filaments of fibers was a significant part of this research. The Finite Element (FEM) model of the unit-cell, which is a small element of the composite which describes all of the mechanical properties of the material, provided the required results of the strain energy with a low volume of computation. The computed loads by FEM were put in derived equations of fracture mechanics. The criterion of strain energy release rate (Gc) have been used. The obtained numerical results showed the growth of delamination along the weft filaments and a sudden change in the point of crossing of the woof filaments. The curves drawn by finite element method showed that the best answer would be given by usage of singular elements for modeling of crack tip comparing by usage brick elements. So results of modeling by singular elements were developed in this paper. Numerical results were in good correlation with the experimental results and the difference was less than 10%.

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Keywords: Composite Material, Woven, Delamination, Modeling, Finite Element, Unit Cell.

 


 

go to top   Implementation of Active Force Control to Disc Brake for Noise-Free Performance
         by S. M. Hashemi-Dehkordi, M. Mailah, A. R Abu Bakar

        Vol. 3. n. 4, pp. 481-488

 

Abstract - Disc brake noise is still considered an elusive problem in the automotive industry. To date, there are a number of solutions that have been proposed including modifying the structural and/or attaching the pad insulator but very few are successful. This paper attempts to describe an active method to reduce disc brake noise and vibration using an Active Force Control (AFC) strategy. A two degree-of-freedom (DOF) disc brake model is considered and adopted in the development of the proposed control system. First, the disc model is simulated and analysed using a conventional closed loop proportional-integral-derivative (PID) controller for vibration and noise control. Later, it is integrated with the AFC element that is designed to robustly reject the disturbances and uncertainties based on the given operating environment. It is found that the integrated PID-AFC scheme is very effective in suppressing the vibration and hence the noise compared to the pure PID controller. This paper also looks into the effect of negative damping on the brake performance.

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Keywords: Active force control, PID controller, Disc brake, Noise and vibration, Negative damping.

 


 

go to top   Experimental Studies on a DI -CI Engine Run with Pongamia Methyl Ester Injection and Methanol Carburetion
         by N. Haribabu, G. RaviKiranSastry, V. J. J. Prasad, B. V. Appa Rao

          Vol. 3. n. 4, pp. 489-493

 

Abstract - Experiment was conducted to evaluate the performance, emission and combustion characteristics along with cylinder vibration of direct injection diesel engine operating in duel fuel mode using Pongamia methyl ester injection and methanol induction. Preheated methanol is inducted into the engine at a particular throttle opening along with intake air stream by a carburetor which is arranged at bifurcated air duct. Pongamia methyl ester fuel was supplied to the engine by conventional fuel injection. The present study is to clarify ignition characteristics, combustion process and knock limit of methanol flow rate in a dual fuel diesel engine, and also to improve the trade-off between NOx and smoke without deteriorating the engine performance. Engine vibration is measured on the cylinder head for different dual fuel combinations to compare the engine performance. Combustion difference can be identified when the vibration is recorded and plotted in the wise of FFT spectrums and time wave forms. The experimental results show that there is minimal change in exhaust gas temperatures and there is better reduction of NOx, HC, CO and CO2 at methanol mass flow rate of 16.2mg/sec. Smoke level was observed to be low and comparable. Improved thermal efficiency of the engine was observed with methanol induction. Vibration levels are comparably low with the above mass flow rate of methanol in the dual fuel operation.

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Keywords: PME, Methanol, Carburetion, Emissions, FFT.

 


 

go to top   Two-Dimensional Theoretical and Numerical Approach of Pollutant Transport in the Lowest Layers of the Atmosphere
         by Ilham Aberdane, Kamal Gueraoui, Mohammed Taibi, Abdelhak Ghouli, Abdellah El Hammoumi, Mohammed Cherraj, Mohammed Kerroum, Myrieme Walid, Omar Fassi Fihri, Yehia Mohammed Haddad

Vol. 3. n. 4, pp. 494-502

 

Abstract - The main objective of the present paper is to establish a two-dimensional theoretical and numerical model for the atmospheric pollution by considering the advection-diffusion-reaction process in a turbulent flow (k-e model) of a Newtonian fluid. A finite volume method is used to solve the equations and to determine the temperature, T, the pollutant concentration profile, c and the fluid velocities u, w, respectively in Cartesian coordinates. This study, considered as an important step in modeling atmospheric pollution, may also be fit to other industrial applications.

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Keywords: Turbulent flow, Finite volume method, Newtonian fluid, Atmospheric pollution, Advection-diffusion-reaction process.

 


 

go to top   Energetic and Economic Feasibility Associated with the Production, Processing and Conversion of Jatropha Oil
to a Substitute Diesel Fuel in India

         by Devendra Vashist, Ahmad Mukhtar

        Vol. 3. n. 4, pp. 503-509

 

Abstract - This study investigates the resource availability, energetic efficiency, and economic feasibility of converting jatropha oil into biodiesel, a substitute diesel fuel.
A resource assessment of jatropha oil generation in India was performed for the period of 2007 onwards. Since India is net importer of vegetable oils, therefore edible oils cannot be used for the production of biodiesel. India has the potential to be a leading world producer of biodiesel, as biodiesel can be “harvested,” and sourced from non-edible oils like Jatropha Curcas, Pongamia Pinnata and Madhuca Indica plants also. Out of these plants, India is focusing on a wild plant, Jatropha Curcas, which can grow in arid, semiarid and wasteland. Jatropha oil production and processing system, which involves its energy and economic analysis is being studied in this paper. Although jatropha plant can be made available in significant quantities at relatively low cost, energetic (energy ratio) and economic feasibilities were estimated for three different system boundaries: (1) conversion of jatropha oil by a continuous-flow transesterification process only with co-product (glycerin) (2) energy required to process jatropha seed to jatropha oil at the Crushing plant and then followed by transesterification. (3) Growth and maintenance of the jatropha plantfollowed by crushing of seeds and then transesterification. Variation in Energy ratios within the three system boundaries based on data available in literatures was calculated. The biodiesel programme in an edible oil importing country (such as India) has to depend upon the availability of non-edible oils. Availability of land for this purpose was carefully assessed.In India if 40% of cultivable wastelands are planned with jatropha, in a period of 20 years it will be possible to substitute over 16 % of petroleum diesel in 2027.It wasalso estimated that production of jatropha oil would be much more than that required for 10% blend with diesel (for use without any engine modification)
.

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Keywords: Biodiesel, Energy ratio, Glycerin, Jatropha, Transesterification.

 



 
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