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Home>Products>Journal and Reviews>I.RE.M.E.>Latest issue
International Review of Mechanical Engineering - November 2009 - Papers
International Review of Mechanical Engineering - Papers
Abstract - The objective of this work is to evaluate the mechanical behavior of welded steel pipes and conduct an analysis of experimental results from the tensile test tube draft and finished after completion of induction welding. Two types of specimens considered (tape flat tube section), the comparison is made in two cases. Mechanical quantities defined, governing the properties of metal, more common, if not the largest, are connected, first, the tenacity of steel is to tell the resistance to deformation, d Secondly, the ductility, that is to say, the ability to deform without breaking, both qualities being in a dependency. Our work with numerical simulations for two types of joints (longitudinal and transverse), the finite element code Castem2000 Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Pull, Draft Tube, Ductility, Strength, Toughness.
Abstract - This study investigates the Euler equations behavior at high angles of attack for a NACA 0012 airfoil. It was shown that the Euler equations could successfully predict the separation behavior under certain conditions. For this purpose, a logical analogy between the physical and numerical viscosities should be established. The produced vortices on the upper side of airfoil were clearly captured due to the fact that the Euler equations could admit rotational solutions. This fact is justifiable also by the Crocco’s theorem which relates the entropy change to the flow parameters. For flux treatment a novel pressure-based method was applied which has currently been developed for incompressible flows resulted in a wider stability and faster convergence. For marching in time, a fifth-order Runge-Kutta scheme has been used. The obtained results are compared with available data in the technical literature. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Euler equations, Subsonic flow, Finite-volume, Angle of attack, NACA 0012.
Abstract -
The
project is designed to examine the surface finish achieved on stainless
steel when machining in a lathe using a cemented carbide tool. The
finish, forces and the chip thickness have been measured and observed
using the talysurf 5 and the scanning electron microscope. A wide range
of parameters were considered. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved Keywords: Surface roughness, Machining stainless steel, Tool wear, Ship thickness.
Abstract - The IZIIS (Institute of Earthquake Engineering and Engineering Seismology)' contribution to development of high quality materials has been seen in realization of several scientific-research projects in the field of high strength concrete in the period from 1992 to 2007. Within the frames of these projects complex laboratory-experimental-analytical investigations have been performed to contribute to definition of the methodology for obtaining high strength concrete exclusively from domestic resources, to investigate nonlinear behaviour of high strength materials and elements as well as to define dynamic behaviour of high strength concrete buildings exposed to seismic actions. In the paper selected part of these complex investigations are presented namely the procedure for nonlinear analysis of elements constructed of high strength concrete and steel. For analytical definition of the bearing and deformability capacity of beams and columns constructed of high-strength materials, an original computer program MPHI-HSC has been developed. The obtaining of moments and curvatures follows the concept of fiber model analysis of cross-section. Having in mind the specific nature of used materials, a stress-strain relationship for confined high-strength concrete as well as stress-strain relationship for high strength steel have been incorporated in the program. The correlation between analytically obtained and experimentally measured values are given in the paper. The results from nonlinear analysis of beam and columns constructed of high strength materials are presented in the form of time histories of forces, displacements and strains in concrete and steel, as well as through hysteretic force-displacement relationships. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: High strength concrete, Moment-curvature, Fiber model analysis, Bearing and deformability capacity, High strength steel, Stress-strain, Force-displacement relationships, Nonlinear behaviour, Quasistatic.
Abstract - The aim of a previous analysis by Samaras and Margaris was the transformation of flow regime maps, given in the literature, into preselected coordinate systems. It is believed that although parameters including the physical properties of phases could give the best possibility for working out universal flow regime maps, phase velocities and fluxes are undoubtedly the most convenient when used. That is why these parameters were chosen for presentation of the new flow regime maps. An attempt has been made to work out new flow regime maps, quite convenient in presenting two-phase airlift pump performance and regime transitions. As a result of this procedure two new regime maps were introduced. In the present paper a third map is presented, giving the void fraction εG versus liquid superficial velocity JL, thus completing all existing pairs among JG, JL and εG. These three maps are given in a 3-D presentation (pseudo 3-D regime map). Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Fluid Mechanics, Mass Transfer, Multiphase Flow, Voidage, Drift-flux Model, Air-lift Pump, Two-phase flow, Regime map, Regime transition.
Abstract -
Analytical solutions play a very important role in heat transfer. The
purpose of the present paper is to carry out the Non-Fourier effect
subjected to heat flux boundary condition. The governing equation
expressed in cylindrical coordinates. Equations are solved by deriving
the analytical solution with method of separation of variables. The
temperature layers and profiles of sample calculations show that, as
much as the Vernotte number is higher, the point can get to higher
temperature during the process. Also, it can be perceived from
temperature profiles that, it is possible that the temperature of
different points of object become even lower than initial temperature.
Keywords: Non-Fourier, Heat Conduction, Relaxation Time, Separation of variables.
Abstract -
Computerized pump design has become a standard practice in industry, and
it is widely used for both new designs as well as for old pumps
retrofit. Such a complex design code has been developed over the past
decade by the author. However, any design method has to accept a set of
hypotheses that neglect in the first design iteration the
three-dimensional effects induced by the blade loading, as well as the
viscous effects. As a result, an improved design can be achieved only by
performing a full 3D flow analysis in the pump impeller, followed by a
suitable correction of the blade geometry and/or the meridian geometry.
The paper presents a fully automated procedure for generating the
inter-blade channel 3D geometry for centrifugal pump impeller, starting
with the geometrical data provided by the quasi-3D code. This is why we
developed an original procedure that successfully addresses all
geometrical particularities of a centrifugal pump. The paper describes
the implementation of our procedure, for centrifugal pump impeller. This
is the initial data for the procedure of discretisation of the impeller
channel needed for the numerical simulation of 3D flow analysis.
Keywords: Conformal mapping method, CAD procedure, Blade design, Pump impeller, Stream surface, Streamline.
Abstract -
Fully developed mixed convection between parallel plates for steady-state
laminar flow is analyzed by making use of the Mathematica system
symbolic computation capabilities. The heated vertical channel is
representative of several problems such as the chimney, the solar panel
or the double-skin envelope. The expressions obtained for the fully
developed velocity, pressure and temperature distributions, are employed
to examine different criteria for the definition of the relative
importance of the natural and forced convection effects, always in terms
of the Reynolds and Richardson numbers. Initially, three previously
studied criteria are considered, namely, the ratio of wall shear
stresses, the ratio of the quadratic means of the buoyancy and viscous
forces terms, and the ratio of the quadratic means of the buoyancy and
pressure forces terms. A new criterion based on the ratio of kinetic
energy generated in the flow due to natural convection and that
generated in total, due to both natural and forced effects, is also
proposed. An application dealing with convection in air flow is
presented for a specific case of a double-skin envelope.
Keywords: Channel Flow, Double-Skin, Mixed Convection, Parallel plates, Wall Temperature.
Abstract - The paper presents an elastic-plastic model with non associated constitutive law exhausting of implicit standard material method. This approach uses a single potential and shows that the non associated behavior can be described as an associated material but with an implicit normality rule. Introducing a new energy functional, minimum principles are established. They lead to prove the solution existence of the boundaries values problem. The incremental stress-strain relationship gives a new tangent matrix decomposition which leads to a variant of Newton-Raphson algorithm using a symmetric tangent operator. Finite element numerical examples are about the Ménard pressuremeter test. Indeed, in spite of its reliability, computer test simulation provides many interesting aspects. Numerical results show the feasibility of the formulation which can be easily integrated in general numerical software. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Constitutive law, Finite element methods, Foundation, Ménard pressuremeter, Solids mechanics.
Abstract - Fluidized bed flash pyrolysis experiments have been conducted on a sample of jatropha oil cake to determine particularly the effects of particle size, pyrolysis temperature and nitrogen gas flow rate on the pyrolysis yields. The particle size of jatropha oil cake was varied in the range of 0.3-1.18 mm. Reaction temperatures were varied from 350ºC to 550ºC.The nitrogen gas flow rate were varied from 1.25 to 2.4 m3 / hour. The maximum oil yield of 64.25 wt% was obtained at a nitrogen gas flow rate of 1.75 m3 / hour, particle size of 0.7-1.0 mm and at a pyrolysis temperature of 500ºC. The calorific value of pyrolysis oil is 19.66 MJ/kg. The pyrolysis gas can be used as fuel gas. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Flash pyrolysis, Fluidized bed, Jatropha oil cake, Pyrolysis oil.
by Aidy Ali, A. B. Sanuddin
Abstract - In this work, characterization of macrostructure, microstructure, hardness, elemental compositions and internal discontinuities of ASTM A516 grade 70 fusion welded joints has been investigated. The welded joints of ASTM A516 grade 70 carbon steel, which are widely used in pressure vessel fabrication were prepared using welding procedures of Manual Metal Arc (MMA), Metal Inert Gas (MIG) and Tungsten Inert Gas (TIG). This comprehensive information provides a practical guide in order to determine the most adequate welding procedure and assisting in understanding the mechanical behaviour of the weld microregimes. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Carbon Steel, ASTM A516 grade 70, Welding.
by Noura. Boucerredj, Mohamed. Meksaouine
Abstract -
This study performs dynamic analysis of nonlinear porous media in the time
domain by using the coupled finite and boundary element methods. The
near field is modeled with conventional finite elements, while the far
field is modeled with the boundary elements which satisfy radiation
conditions. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Extended mesh, Implicit- explicit algorithm, Saturated porous medium, Silent boundary condition, Small mesh, Two phase system.
Abstract - Most of the currently available optimization strategies for machining operations are based on economic parameters such as production cost and machining time. In most cases, however, size tolerance is the first criterion for accepting the manufactured parts. As a result, these strategies might not be applicable in practice, despite their economic advantages. This paper proposes a new optimization strategy for a single-pass peripheral end milling process based on both technical and economic parameters, namely, specified parts tolerances and economical cutting speeds. First, the cutting speed is selected based on an economic parameter, such as the minimum cost per part or the maximum production rate. Then the circular direction search optimization strategy is employed to determine the best combination of feed rate and radial depth of cut to satisfy the specified part tolerance. The results indicate that the proposed strategy can be implemented successfully for process optimization. By being based on both technical and economic parameters, it provides a rational solution to the peripheral end milling optimization problem. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: End milling, Process optimization, Size tolerance, Circular direction search.
Abstract - The main purpose of this paper is to analyze the four stroke multi-cylinder diesel engine coupling generator system for torsional vibration. In this work the modified Holzer method is used for forced vibration analysis of mass-elastic system and to determine the natural frequencies of torsional vibration of a multi-cylinder inline diesel engine generator set. The natural frequency of a system is important as it is the main cause of various types of failures. The high level harmonic forcing torque developed in engine can produce large torsional stress levels resulting in early fatigue failure in crankshaft. Therefore by knowing the natural frequencies and frequency modes of the engine the limitations in use of the engine working speeds can be fixed (i.e. for present case 1317.00rpm). Analyzing only the lower harmonic orders (½, 1, and 1½) of the speed variation spectrum can filter out the distortions produced by the dynamic response of the crankshaft. The information carried by these harmonic orders permits to establish correlations between measurements and the average gas pressure torque of the engine, and to detect unbalance and identify faulty cylinders. Detail experimental reading were taken on diesel engine coupling generator set on the test bed of Greaves Cotton Ltd Pune. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Critical speed, Diesel Engine, Holzer Method, Natural Frequency, Imbalance.
Abstract - In recent
years, interests in ocean-logical research and developments have grown
on an international scale. This increased the demand for an independent
power plants which can operate underwater with no requirements for power
transmission cables and support vessels or bases. The closed cycle
diesel engine, CCDE, provides an economic solution that is strongly
needed. Such solution is expected to fill the energy gap for submarine
between the low performance conventional diesel electric system and high
performance nuclear reactor plant. The interrelationships between the
non-air oxidants with moderate gases for synthetic atmosphere and
combustion performance are either not understood or not well documented. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: CCDE, AIP, SAD, Diesel engine, Combustion.
Abstract - Unsatisfactory design of mechanical ventilation systems in underground car parks would give a poor and unhealthy indoor environment. Carbon monoxide (CO) is recognized as one of the most important pollutants that need to be regulated in urban atmospheres due to its toxicity and implications for human health. This study draws attention to the effect of exhaust fan height on the carbon monoxide (CO) dispersion in enclosed parking facilities. A mathematical model is presented in a general computer code that can provide detailed information on CO concentrations as well as airflow fields prevailing in three-dimensional enclosed spaces of any geometrical complexity. This model involves the partial differential equations governing CO levels and airflow transfer in large enclosures. In this paper the performance of the two types of ventilation systems (Suction-only and Supply-Suction) with different positions of exhaust fan and different occupational percentage was studied and the CO concentrations in the breathing zone were compared in order to find the most appropriate position for the exhaust fan to be used in underground garages in both case. It was found that the carbon monoxide concentration in the breathing zone has a strong relation to the exhaust fan position. The simulation results could be used as a base for ventilation design for enclosed garages. Aimed at a proper ventilation system selection for a more healthy and comfortable working microenvironment. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: CFD, Simulation, Ventilation efficiency, Underground garage, Car park, Carbon monoxide, Air quality.
Abstract - Several different experimental test techniques can be used to assess the behavior of masonry structures for a wide range of objectives (vertical capacity, lateral load, seismic behavior, etc.). In such context, this paper presents several setups considered from the simplest one for in-situ use, to more complex ones used in laboratory conditions. Some examples are presented as used to characterize the expected seismic response through in-plane and out-of-plane tests on masonry walls adopting simple in-situ or complex laboratory setups. Among these examples, two new test setups developed for in-situ assessment of existing structures are presented where good results were obtained. Finally, some comments are included regarding the efficiency of simple test schemes when compared to more complex and elaborated test setups as well as the applicability of the later to in-situ or laboratory conditions regarding costs, time and the requirements for their use. The paper content is expected to help researchers on choosing the suitable testing option for each particular experiment. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Experimental, In-Situ, Masonry, Monitoring, Earthquake Resistance.
Abstract - The use of external cables has gained popularity in bridge constructions because of its simplicity and cost-effectiveness. Moreover, the technique of external cables is applied not only to new structures but also to existing ones, which need to be repaired or strengthened. The aim of this paper is to present a static analysis of a concrete beam with external pre-stressing cables subjected to a moving load using a transfer matrix method. The transfer matrix technique is proposed to evaluate the load effects produced by the influence lines at deviator points of the beam and bearings. The performance of the method was accomplished through model validation and some characteristic responses investigated. A parametric study was also performed to examine the effect of the friction at the deviators on the behaviour of the externally pre-stressed concrete beam. The results obtained are discussed with emphasis on the effects of friction. The calculation procedure has been implemented in a Fortran computer program. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Moving loads, Influence lines, External cables, Transfer matrix method, Linear elastic Support, Deviators, Friction effect.
by Hasim Altan, Jitka Mohelnikova
Abstract - The paper deals with an energy saving case study of a renovated building in comparison with the building energy balance before renovation. The renovation was carried out in the building envelopes such as external walls, floor on ground and the flat roof for the improvement of thermal insulation properties of the investigated building. The renovation has brought forward energy saving effects, which are important for both reducing energy consumption for heating during winter seasons and the associated heating costs. In addition, the renovation represents a positive environmental impact due to the reduction of carbon dioxide emissions from such dwellings. The energy renovation of the case study building evaluated was used as a base for an estimation of energy savings and reductions of carbon emissions within a housing estate residential complex with twenty similar buildings. The study presents the importance of having such thermally insulated building envelopes in building together with windows that also have good thermal property and insulation quality for the reduction of overall energy consumption. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Energy Savings, Buildings Retrofit, Thermal Insulation, Heat Losses, Sustainable Buildings.
Abstract - Results from tests conducted on thin welded steel-concrete stubs are presented in this paper. The studied section was made of two cold formed steel plates with U shape welded to form an I steel section. The main studied parameters were: the profile height (slenderness ratio), the type of in filled concrete and its age. A total of 49 stubs were tested under axial compression up to failure, illustrating some interesting aspects of the overall behaviour of such composite sections. The test results clearly indicate that the length of empty profile has an important effect on the failure mode was rather a local buckling mode with steel flanges deformed outwards and inwards. Regarding partially encased composite columns, the load carrying capacity increased significantly with the presence of the different concrete mixes considered, and also with the concrete age. The mean concrete contribution reached 83% at 28 days and increased by 13% 6 months later. The failure mode was by fully or partial crushing of concrete, steel flange buckling and steel-concrete separation. Copyright © 2009 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Axial loads, Buckling, Composite column, Concrete slag, Steel, Ultimate strength.
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