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International Review of Mechanical Engineering - Papers
Effect
of the Resin Type on the Acoustic Activity and the Mechanical Behavior
of E Glass/Polymer Resin ±55°Filament Wound Pipes Under Axial Loading
by Ated Ben Khalifa,
Mondher Zidi
Vol. 5 n. 5, pp. 792-797
Abstract - Acoustic
emission is one of the most innovative of non-destructive testing
techniques because makes it possible to follow in real time the damage
of composite materials. The aim of this paper is to study the effect of
variation in the resin type on the mechanical behavior and the acoustic
activity of the filament wound pipe under monotonous axial loading.The
results obtained show that the mechanical behavior as well as the
acoustic activity of the filament wound pipe change for each type of
studied resin.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Filament Wound Pipe, Resin Type, Tensile Test, Mechanical Behavior, Acoustic Activity.
Mechanical
Stress Analysis in a Dynamic Graphite-Graphite Contact: Consequences on
Wear
by Y. Mouadji, A.
Bouchoucha, M.A. Bradai, H. Zaidi
Vol. 5 n. 5, pp. 798-803
Abstract - In order to evaluate the wear of tribological pairs, it is important to know the type and the magnitude of the mechanical stress imposed at the dynamic contact. To do this, a numerical modell based on quasi-analytical solutions has been developed using a Matlab program. This modell can take into account the evolution of the mechanical stress generated in a dynamic contact as a function of the loading conditions and the coefficient of friction. This tool allows, by exploiting the calculation results, to obtain stress fields in every point under contact. To analyze these stress fields, we have considered the solution of the semi-infinite plane problem given by McEwen [1] and Johnson [2], where the contact pressure of Hertz [3] is limited to a circular contact area of radius a. The discussion of the results is based on the correlation between the limit values of the contact stress and the experimental results of the coefficient of friction and wear.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Friction, Wear, Stress Field, Contact Modell, Graphite, Speed.
Fracture
Toughness Transferability in Pipe with External Oriented Defect
by B. El hadim, H. El
minor, M. El hilali
Vol. 5 n. 5, pp. 804-811
Abstract - The
problem of pipelines subjected to external defects caused by foreign
scratch objects or gouges is treated. The external oriented defect
represented by a blunt notch in the pipe under internal pressure has
been considered and an elastic-plastic finite element method is applied
to this survey.
The critical notch stress intensity factor (or toughness of material) is
evaluated for various outside diameters of pipe and various notch defect
orientations. The fracture toughness transferability is treated by using
the stress triaxiality and introducing of a new transferability
parameter called pt. application of this method has been made on bending
specimens extracted from the pipe.
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Keywords: External Oriented Defect, Pipe, Fracture Toughness, Transferability Parameter.
Experimental
Studies of Film Boiling Phenomena on Carbon Heated Surface
by S.Illias,
M.A.Idris, M.Z.M.Zain
Vol. 5 n. 5, pp. 812-817
Abstract -
The purpose of this research is to study and examine the nucleate-boiling
and film- boiling phenomena on carbon heated surface, which occur when a
water droplet collided with the heated surface at a very high
temperature (100ºC-420ºC). When the surface temperature reaches a
maximum value, the critical superheated surface is suddenly covered with
a vapor layer. Because of the vapor layer’s lower thermal conductivity,
this vapor layer insulates the surface. This condition of vapor film
insulating the surface from the liquid characterizes film-boiling. The
carbon boiling curve that obtained from the experiment is examined in
order to study the relation between carbon boiling curve and Leidenfrost
effect. According to the Leidenfrost effect, liquids cannot touch a
surface with a temperature above their boiling point because evaporation
forms a cushion of vapor preventing contact. The higher the surface’s
temperature above the boiling point of the liquid, the more rapid
evaporation occurs. The carbon material was heated in order to study
this droplet dispersion and bounding phenomenon in the droplet collision
boiling system. The phenomenon was photographed by using a high-speed
camera (10,000 fps) from the horizontal direction.
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Keywords: Nucleate-Boiling, Film-Boiling, Droplet, Thermal Conductivity, Heated Surface.
Activated
Carbon for Drying Compressed Air for Low Pressure Applications
by N.S.
Senanayake, D.M.K.K.Dissanayake
Vol. 5 n. 5, pp. 818-822
Abstract - This paper presents the results of a study on the use of activated carbon for dehydration of compressed air. Compressed air consists of moisture and other impurities that are detrimental to smooth operation of machine tools and equipment. Usually dehydration is done centrally by different methods such as refrigeration drying, deliquescent drying, membrane drying, and adsorption drying. In adsorption drying, silica gel and activated alumina are widely used and these materials are relatively expensive compared to activated carbon which is locally produced using different sources of biomass. The study proved that activated carbon adsorbent beds can successfully be used to dry compressed air at 4 – 8 bar to meet the industry requirements.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Activated Carbon, Drying of Compressed Air, Adsorption Drying.
.
Analytical
Solution for Chemically Reacting Free Convective Couple Stress Fluid in
an Annulus with Soret and Dufour Effects
by D.
Srinivasacharya, K. Kaladhar
Vol. 5 n. 5, pp. 823-833
Abstract - The purpose of this research is to study and examine the effects of the cross diffusion (namely the Soret and Dufour effects) in the presence of chemical reaction on fully developed natural convection heat and mass transfer of a couple stress fluid in an annulus formed by two circular cylinders. The governing non-linear partial differential equations are transformed into a system of ordinary differential equations using similarity transformations. The resulting equations are then solved for approximate analytical series solutions using Homotopy Analysis Method (HAM). Profiles of dimensionless velocity, temperature and concentration are shown graphically for various values of Dufour number, Soret number, Couple stress parameter and chemical reaction parameter.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Free Convection, Couple Stress Fluid, Soret and Dufour Effect, Heat and Mass Transfer, HAM, Chemical Reaction.
Computational
Analysis of Mixed Convection over Heated, Vertical Rectangular Fin
Array, at Richardson Number of Unity
by J.P. Shete ,
N.K. Sane , S. Pavithran
Vol. 5 n. 5, pp. 834-842
Abstract - Fins are
widely used to increase the heat removal from a given structure.
Vertical fin arrays losing heat under natural convection and forced
convection find important applications in cooling electronic devices. In
a few applications both modes have a contribution in cooling. In the
current work, numerical analysis of mixed convection from isothermal
vertical rectangular fin array, at Richardson number of unity is
presented. At this Richardson number, both natural and forced convection
modes are comparable. Computations are made for assisting and opposing
modes of mixed convection for a range of temperature differences. Other
objective of this work is to find the optimum spacing zone. For given
temperature differences, Nusselt numbers are small for natural
convection and become large for mixed modes, at all spacings. , Optimum
spacing is found for a range of temperature differences
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Keywords: Cooling of Electronic Devices, Mixed Convection, Vertical Fin Array.
Use
of Flat Mini Heat Pipes for the Thermal Management of High Dissipative
Electronic Packages for Avionic Equipments
by Zaghdoudi, M.C.,
Tantolin, C., Sarno, C.
Vol. 5 n. 5, pp. 843-855
Abstract – An experimental study is realized in order to verify the mini heat pipe concept for cooling high power dissipation electronic cards. Two kinds of card substrates are considered: alumina and FR4 epoxy, and the chip on board technology is used. Different prototypes of configurations on reporting the chip on the card are tested. The thermal measurements show that the use of heat pipes allows for significantly reduced temperature gradients and maximum chip temperature decrease.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electronics Cooling, Electronic Packages, Thermal Management, Mini Heat Pipes.
Application
of Lattice Boltzmann Method for Lid Driven Cavity Flow
by Fudhail Abdul
Munir, Mohd Irwan Mohd Azmi, Mohd Rody Mohd Zin, Mohd Azli Salim, Nor
Azwadi C. Sidik
Vol. 5 n. 5, pp. 856-861
Abstract -
In this paper, numerical simulations to predict fluid flow inside lid
driven square and triangular cavity is carried out. The streamline
patterns obtained from the simulations is investigated and studied.
Lattice Boltzmann Method is used to predict the flow in lid driven
cavities. In order to simulate the flow, derivation of macroscopic
hydrodynamics equations from the continuous Boltzmann equation need to
be performed. Then, the numerical results of shear-driven flow inside
square and triangular cavity are compared with results found in
literature review. Present study found that flow streamline patterns are
affected by the geometry of the cavity and the Reynolds numbers used.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Lid Driven Cavity, Streamline Patterns, Lattice Boltzmann Method.
Mechanical
Investigation of the Nozzles Attached to Pressure Vessels
by M. M. S.
Fakhrabadi, V. Norouzifard, B. Dadashzadeh, M. Dadashzadeh
Vol. 5 n. 5, pp. 862-866
Abstract -
This paper presents the mechanical investigation of the nozzles attached
to pressure vessels including their elastoplastic modeling and
stress-strain behaviors. Stress concentration occurs in the contact zone
between the nozzle and the shell of the vessel due to the variation of
the cross sections. Limit pressure and local stress concentration factor
are obtained from the modeling.
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Keywords: Pressure Vessel, Nozzle, Elastoplastic Modeling.
Deposition
of Solid Particles in Convective Flow over Backward-Facing Step under the Effect
of Radiative Heat Transfer
by V. Golkarfard,
S. A. Gandjalikhan Nassab, A. B. Ansari
Vol. 5 n. 5, pp. 867-875
Abstract - A
numerical simulation procedure for studying deposition of aerosol
particles in a laminar convection flow of radiating gas over a
backward-facing step including the effect of thermal force is developed.
In the gas flow, all of the heat transfer mechanisms consisting of
conduction, convection and radiation take place simultaneously. Behavior
of solid particles is studied numerically based on an Eulerian–Lagrangian
method. Two dimensional Navier-Stokes and energy equations are solved
using CFD techniques, while the radiating transfer equation (RTE) is
solved by discrete ordinate method (DOM) for calculating radiative heat
flux distribution. The objective of this research is to study the
effects of Reynolds number and diameter variation, thermophoresis and
radiation on deposition of particles. The thermal condition involved
constant wall temperature for both top and bottom walls in which the
bottom wall has higher temperature. The variation of Reynolds number is
a parameter that influences the deposition of particles. Numerical
results show a decrease in deposition percent by increasing in Reynolds
number. Thermophoresis causes increases in deposition for 0.1 µm
particles and its effect reversed for 1 µm ones. Finally, it is revealed
that radiation causes slight increase in particle deposition.
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Keywords: Backward Facing Step, Laminar Forced Convection Flow, Radiation Heat Transfer, Thermophoresis, Particle Deposition.
Numerical
Study of the Mixing of Co-Axial Jets
by Fernando M. S.
P. Neves, Jorge M. M. Barata, André R. R. Silva
Vol. 5 n. 5, pp. 876-883
Abstract -
This
paper presents a numerical study of the effect of the turbulence
intensity in the turbulent mixing of coaxial confined jets. The
objective of this work is to study the effect of the initial levels of
turbulence of each coaxial jet in the process of turbulent mixing for
diameter ratios less than 2, which is the case of very low bypass
turbofan engines. The computational method was tested using the
available experimental data, and revealed good capabilities for the
simulation of this kind of flows. The effect of the velocity ratio of
the two streams is presented for velocity ratios of the two streams of
0.3, 1.5, and 6, and turbulence intensity ratios between 10-5 and 105.
The results revealed that for relatively high turbulence intensities of
the outer jet a vortex is always present for velocity ratios of 6 or
larger, and this is independent of the turbulence intensity ratio. When
the turbulence intensity of the inner jet is kept constant and the ratio
of turbulence intensities is increased, the recirculation zone decreases
in size, its center moves further upstream until it disappears
completely. The existence of a favorable pressure gradient as a similar
effect, revealing that this is an additional parameter to be taken into
consideration together with the velocity ratio and turbulence intensity
ratio as far as the recirculation zone is concerned.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Co-Axial Jets, Gas Turbine Engines.
Experimental
Investigation of Cavitation in a Centrifugal Pump with Double-Arc
Synthetic Blade Design Method
by
Spyridon D. Kyparissis,
Dionissios P. Margaris
Vol. 5 n. 5, pp. 884-892
Abstract - Cavitation, in many cases, is an undesirable occurrence. In hydrodynamic devices such as propellers and pumps, cavitation causes a great deal of noise, damage to components, vibrations and a loss of efficiency. In the present study, a centrifugal pump with double-arc synthetic blade design method is examined experimentally in a pump test rig under cavitating and non-cavitating conditions. The pump test rig, where the experiments are carried out, allows optical observation of the cavitation inception and development with the aid of the stroboscopic light source. Studying the non-cavitating condition, the total performance head curves are illustrated for three different rotational speeds. On the other hand, examining the cavitating condition, the head drop curves are presented in order to investigate the cavitation inception. In addition, the vapour distribution along with the blades at the leading edge in the region of the suction side is depicted for the tested range of flow rates and rotational speeds.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Cavitation, Centrifugal Pump, Double-Arc Design, Experimental Study, Pump Test Rig.
Modeling
of Surface Finish and MRR in Low Cost Internal Grinding
by Dr. K. Kishore,
Dr. V.V. Satyanarayana, P. V. Gopal Krishna, G. Kiran kumar
Vol. 5 n. 5, pp. 893-897
Abstract
- A Grinding machine is a machine tool used for finish machining process
by employing an abrasive wheel as the cutting tool. Each grain of
abrasive on the wheel’s surface cuts a small chip from the workpiece due
to shear deformation. Grinding machines remove material from the work
piece by abrasion, this results in substantial amount of heat
generation. It is important to use a coolant to cool the workpiece so
that it does not overheat and go outside its tolerance. Internal
grinding is used to grind the internal diameter of the workpiece.
Tapered holes can be ground with the use of internal grinders that can
swivel on the horizontal. The present work focus on internal grinding
process by a retrofitted grinding wheel attachment on a lathe leading to
construction of models for surface finish and MRR. Experiments are
conducted using Taguchi orthogonal array and the results are obtained.
This setup is observed to be useful for small industries and the finish
is comparable with original internal grinding processes.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Retro Fitting, Surface Finish, MRR, Depth of Cut, Feed Rate, Wheel Speed and Work Speed.
Numerical
Study of Entropy Generation in Laminar Forced Convection Flow over Inclined
Backward and Forward Facing Steps in a Duct
by M. Atashafrooz,
S. A. Gandjalikhan Nassab, A. B. Ansari
Vol. 5 n. 5, pp. 898-907
Abstract -
This research work presents a numerical investigation of entropy
generation in laminar forced convection of gas flow over a recess
including two inclined backward and forward facing steps in a horizontal
duct. Although the flow in this type of geometry has many applications
in thermal systems, but this type of convection flow has not been
analyzed by any investigator. For calculation of entropy generation from
the second law of thermodynamics in a force convection flow, the
velocity and temperature distributions are primary needed. For this
purpose, the two-dimensional Cartesian coordinate system is used to
solve the governing equations using the computational fluid dynamic
techniques, while the Blocked off Method is employed to simulate the
inclined surfaces. The numerical results are presented graphically and
the effects of step inclination angle, recess length and Reynolds number
on the distributions of entropy generation number, Bejan number and
total entropy generation are investigated.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Entropy Generation, Laminar Forced Convection, Inclined Backward and Forward Facing Steps, Recess.
Inverse
Problem of Rocket Nozzle Throat for Estimating Inner Wall Heat Flux by
Broydon–Fletcher–Goldfarb–Shanno & Conjugate Gradient Method
by H. Khoshkam, M.
Alizadeh
Vol. 5 n. 5, pp. 908-917
Abstract -
This study employs conjugate gradient method with adjoint Problem and
variable metric method to estimate inner wall heat flux of rocket nozzle
throat. Heat flux in nozzle is important since an enormous heat flux
from the jet flow with high temperature can lead to the throat section
increases and it leads to reduce in the nozzle thrust efficiency and
Life extension of the nozzle. The accuracy of the solutions of the
inverse problem is examined through three given heat fluxes with given
measurement errors. The examinations show that with the BFGS and CGM
method, satisfactory solutions can be obtained when the measurement
errors are not large and in large error, the CGM method is more accurate
than BFGS. Moreover, the results show that the applied method converge
very rapidly and is not so sensitive to the measurement errors. The
temperature distribution with estimate flux is too near to real
temperature distribution. Therefore, methods can be used to the heat
conduction problem in the nozzle.
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Keywords: Flux Estimation, Conjugates Gradient Method, Variable Metric Method, Nozzle Throat, Broydon–Fletcher–Goldfarb–Shanno.
Study
and Simulation of Thermal Buckling in a Thin Rectangular FGM Plate
by Mahdi Hamzehei,
Mostapha Raki
Vol. 5 n. 5, pp. 918-926
Abstract -
Equilibrium and stability equations of a rectangular plate made of
functionally graded material (FGM) under thermal loads are derived,
based on the higher order shear deformation plate theory. Assuming that
the material properties vary as a power form of the thickness coordinate
variable z and using the variational method, the system of fundamental
partial differential equations is established. The derived equilibrium
and stability equations for functionally graded plates (FGPs) are
identical to the equations for laminated composite plates with 51
layers. A buckling analysis of a functionally graded plate under one
type of thermal loads is carried out and results in closed form
solutions, uniform temperature rise and gradient through the thickness
are considered, and the buckling temperatures are derived. The critical
buckling temperature relations are reduced to the respective relations
for functionally graded plates with a linear composition of constituent
materials and homogeneous plates The results are compared with the
critical buckling temperatures obtained for functionally graded plates
ANSYS software (FEM) given in the literature. The study concludes that
higher order shear deformation theory accurately predicts the behavior
of functionally graded plates.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Stability of Plate; Thermal Buckling; Rectangular Plate; Functionally Graded Material; Higher Order Shear Deformation Theory.
Experimental
Investigation of Different Heat Recovery Systems in Leisure Center and Its
Effect on CO2 Emission
by M. M. Abo Elazm
, A. F. Elsafty
Vol. 5 n. 5, pp. 927-932
Abstract -
Nowadays the crisis of energy is one of the most important problems of
the world. Building units are the first consumer in world energy.
Because of this, in design of Green Buildings the most important
challenge is reduction of energy consumption in buildings. Leisure
centers are also known as high energy consumers, especially if they have
large ice rinks and swimming pools. The aim of this paper is to
investigate different heat recovery concepts, by using the heat rejected
from the condenser of the refrigeration unit to heat the water of
swimming pool especially in winter. An experimental model has been
constructed to contribute in solving the problem of energy shortage. The
model installed includes an ice rink, a swimming pool and two different
condensers. A comparison between different cases of operation to obtain
the maximum energy saving was carried out. The results show that the
energy saving was about 30% by using both air and water cooled
condensers in series compared to the air cooled condenser only. The
results also showed a significant decrease in the time required for the
ice formation by using both air and water cooled condensers.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Energy Saving, Heat Recovery, Ice Rinks, Leisure Centers.
An
Exact Solution for the Vibration FGM Hollow Cylindrical Shell Based on High
Order Theory under Free-Simply Support Boundary Conditions
by M.Setareh,
M.R.Isvandzibaei
Vol. 5 n. 5, pp. 933-940
Abstract - Study of the vibration of thin cylindrical shells made of a functionally gradient material (FGM) composed of stainless steel and nickel is very important. The objective is to study the natural frequencies and the effects clamped-free boundary conditions on the natural frequencies of the functionally graded cylindrical shell. The study is carried out using third order shear deformation shell theory. The analysis is carried out using Hamilton’s principle. The governing equations of motion of functionally graded cylindrical shells are derived based on third order shear deformation shell theory. Results are presented on the frequencies characteristics and the effects of free-simply support boundary conditions on edge end functionally graded cylindrical shell.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Vibration, Cylindrical Shell, Free-Simply Support.
Using
Homotopy Analysis Method to Determine Profile for Disk Cam by Means of
Optimization of Dissipated Energy
by Hamid M.
Sedighi, Kourosh H. Shirazi
Vol. 5 n. 5, pp. 941-946
Abstract - Select a particular shape for cam profile can play an important role in reduction of energy in automobile motors. Engineers try to reduce this dissipated energy to improve the motor operation. This paper obtains nonlinear governing equation of disk cam follower motion and optimizes it with calculus of variation. Because of optimum cam profile, also, maximum acceleration of the follower is decreased. Finally, we solve it analytically by means of Homotopy analysis method and numerical results have been reported to prove the soundness of the analytical method.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Homotopy Analysis Method; Cam Profile; Optimization of Dissipated Energy.
Path-Whispering
in a Virtual Environment
by Fawaz Y. Annaz
Vol. 5 n. 5, pp. 947-951
Abstract - A mobile robot physically navigates its way to a goal in a virtual maze that was created on a computer. The maze is made up of traversable and un-traversable grids, a starting point and a goal. Based on the immediate (left, right and ahead) surrounding information revealed to it, the robot makes a decision to navigate its way to the next location, which is reported to and traced on the virtual maze. Data exchange is achieved through discrete communications between the robot and the computer via Bluetooth. Real time merging of a virtual maze to a mobile robot allows for rapid navigation algorithm development for any foreseeable/target application with minimal cost and time. To cater for realistic rescue missions, two searching algorithms were implemented; the modified wall-touching is implemented in regions outside a proximity range, where victim’s calls cannot be heard; and a modified pledge algorithm, which is activated once the robot crosses into the proximity range region. Since this paper aims for revealing the shortest rescue path to other robots or humans, the robot is capable of eliminating double treaded paths, hence increasing the efficiency of any further support missions.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Mobile Robot, Maze Solving, Virtual Maze.
Modeling,
Control and Analysis of a Serial and Parallelogram Lower Member Mechanism
by Alvaro Uribe, João
Rosário, Luciano Frezzatto
Vol. 5 n. 5, pp. 952-960
Abstract - This work
presents the modeling, control and analysis of a serial and
parallelogram mechanisms for designing a lower member assisting motion
device. Current most known developments do not cover a wide range of
population due to costs, requirements and availability of these devices.
The robotics impact on improving health care through rehabilitation or
motion assisting devices has been increasing as the technological trends
have advanced in recent years. The methodology taken for developing this
work starts with the mechanism design, so mechanical properties such as
masses and inertias are known. This information allows performing the
kinematics and dynamics analyses for choosing the actuator and control
system while improving the mechanism design for executing gait and
exercise motions. The validation of both mechanisms dynamics is
accomplished through the analysis of the experimental torques obtained
after simulation and the linearization of the model for implementing and
tuning the control system.
Copyright © 2011 Praise Worthy Prize S.r.l. -
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Keywords: Assisting Motion, Lower Member, Parallelogram, Serial.
Parametric
Study of Electro-Hydraulic Servo Valve Using a Piezo-Electric Actuator
by S. F. Rezeka,
A.Khalil, A.Abdellatif
Vol. 5 n. 5, pp. 961-967
Abstract - This paper deals with the mechatronics approach for the design of a piezoelectric actuator and its integration into a servo valve. A piezo-element is introduced as an actuator, instead of conventional electrically operated torque motor, to operate the spool valve. The non dimensional equations describing the system were derived. PD controller was also synthesized. Parametric simulation was conducted to study the effects of the system parameters on its performance. The simulation results are presented and discussed.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Electro-Hydraulics, Servo Valve, Piezo Actuator, PD Control, Parametric Study.
The
Effect of the Fibre Orientation on the Failure Load of Face Sheets Composite
Sandwich Beams
by F.Bourouis, F.Mili
Vol. 5 n. 5, pp. 968-972
Abstract - Sandwich
beams subjected to three points bending may fail in several ways,
including tension or compression failure of the facing; face yielding
and face wrinkling. In this paper three face sheets materials were used
to study the effect of the fibre orientation on static failure of
composite sandwich beams carbon/epoxy, kevlar/epoxy, glass/epoxy of
stacking sequence [+θ/-θ] 3s, [0°/90°] 3s and
[45°/-45°]3s.
The stresses in the face were calculated using maximum stress criterion
and the simple beam theory, including transverse shear effect. The
obtained different results show that the sandwich beams with
carbon/epoxy, and glass/epoxy face sheets are the best materials, in
return the kevlar /epoxy facing characterised by a low mechanical
resistance in compressive and tensile. The critical failure loads,
depends on the properties of the face sheets materials and the fibre
orientation.
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Keywords: Beam Theory, Fibre Orientation, Transverse Shear, Wrinkling, Yielding.
An
Overview on Thermal Barrier Coating (TBC) Materials and Its Effect on
Engine Performance and Emission
by Pankaj N. Shrirao,
Anand N. Pawar, Atul B.Borade
Vol. 5 n. 5, pp. 973-978
Abstract - Ceramic based thermal barrier coatings are considered as candidate materials for coating of engineering components subjected to elevated temperatures in operating conditions. In this study efforts are taken to gather the information regarding the TBC materials, Bond coat materials, coating methods and effect of TBC materials on engine performance and emission. Ceramics, in contrast to metals are often more resistance to oxidation, corrosion, wear as well as being better thermal insulator. Many researchers have carried out large number of studies on LHRE concept. In case of LHR engine almost all theoretical studies predict improved performance but many experimental studies shows different picture. It is concluded that much more research is needed to overcome the practical problems before LHR engines can be put into production.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Diesel Engine, TBC, LHRE.
Process Robustness in a Dimensional Testing Laboratory
by Caterina Poustourli, Vrassidas I. Leopoulos
Vol. 5 n. 5, pp. 979-986
Abstract - In this study we consider a method to make robust the process of high-precision length measurements. Quality improvement efforts in many instances have been directed at reducing the variation of a particular characteristic around a nominal design specification. In the included case study we organized and executed controlled experiments for the comparative measurement of the inside diameter of plain ring gages in the infrastructures of an accredited Laboratory.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Process Robustness, Design of Experiments, Taguchi, Quality Improvement, Length Measurement.
Analytical Solution to Transient Temperature Field in Semi-Infinite Body Caused by Moving Ellipsoidal Heat Source
by Aniruddha Ghosh, N.K.Singh, Somnath Chattopadhyaya
Vol. 5 n. 5, pp. 987-992
Abstract - Submerged Arc Welding process (SAW) provides high quality voluminous deposition process. It has lot of social and economical implications. Lot of critical input variables are involved in this process which are needed to control to get quality weld. Main input variables of this process are function of temperature distribution on the welded plates. Critical investigation of the transient temperature distribution is important for maintaining quality of the Submerged Arc welded plates. This paper makes an attempt to uncover an important domain of the studies of temperature distribution during submerged arc welding process. This analysis may pave the way for the application of micro structural modeling, thermal stress analysis, residual stress/distribution and simulation in welding process. Prediction of temperature variations of entire plates during welding is done through an analytical solution. It is derived from the transient multi dimensional heat conduction of semi infinite plate. The heat input that is applied on the plate is considered to be same amount of heat lost form electric arc. It is assumed that a moving double ellipsoidal heat source with Gaussian distribution is responsible for Submerged Arc Welding process for some input parametric settings. In the analysis it has been observed that the predicted temperature distribution values are in good agreement with the experimental results for a particular input parametric setting.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Submerged Arc Welding, 3-D Gaussian heat distribution, Multi dimensional heat flow equation, Ellipsoidal heat source.
Research Methodology of an Integrated Approach for Thermal Mapping of Hot Section Components of Gas Turbine Engines
by Sachin V. Bhalerao, Dr. A. N. Pawar, Dr. Atul B. Borade
Vol. 5 n. 5, pp. 993-999
Abstract - High levels of thrust demanded from modern gas turbines have led to higher turbine entry temperatures with concomitant detrimental effect on the hot section components such as turbine rotor disc, blade and nozzle guide vane.In a quest to increase the efficiency and power of a gas turbine engine designers are continuously trying to raise the maximum turbine inlet temperature .Further economical and todays environmental concerns continue to provide impetus for operating the aeroengines at ever increasing temperatures thereby improving the thermodynamic efficiency and reducing pollutant emissions. But on the other hand, the maximum allowable metal temperature needs to be limited to 1400oC even in the case of the most advanced super alloys. Accurate full-field assessment of metal temperatures of hot section components is essential for gas turbine designers not only to prevent hot spots but also to produce reliable and durable engines. Gas turbine engineer would have an affluence of useful data if a permanent full-field record of actual hardware temperatures, i.e., metal temperatures, could be made from an operating gas turbine. Conventional thermometry falls short to record the thermal gradient across the various hot section components due to certain limitations. Temperature sensing thermal paints provide a better alternative but the data interpretation issue using the thermal paints is still under research. In this article an inline effort taken to develop a proper research methodology for implementation of a thermal mapping technique of gas turbines using thermal paints is discussed.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Thermal Mapping ,Gas Turbines, Thermal Paints, Automated Thermal Interpretation
The Pseudo Radiation Energy Amplifier (PREA)
by A. Boucenna
Vol. 5 n. 5, pp. 1000-1005
Abstract - In this paper we show that a gray body which separated from vacuum by a material interface and submitted to outside incident radiation can behave like a Pseudo Radiation Energy Amplifier. The Earth (Earth + atmosphere) is not a simple isolated gray body but it is in fact a Pseudo Radiation Energy Amplifier with adequate reflection coefficients. The balance of the energy exchanged between Earth and outer space is reconsidered and the estimated Earth’s ground temperature mean value 15 °C is then derived.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Gray Body Radiation, Reflection Coefficient, Material Interface
A Simplified Method for Thermally-Induced Volumetric Error Compensation
by Yuxia Lu, M. N. Islam
Vol. 5 n. 5, pp.
1006-1012
Abstract - The thermally-induced volumetric error of a machine tool has been recognised as a major contributor to dimensional and geometric errors of component parts produced on it. Consequently, considerable research has focused on compensating for this type of error. The traditional model of compensation for thermally-induced volumetric error of a three-axis machine tool requires measuring 21 geometric error components, which are difficult and time consuming to gather. This paper describes the development of a simplified method of compensating for thermally-induced error based on only three axial positioning errors, which are assumed to be functions of ball-screw nut temperature and travel distance. It is a more efficient and comparatively cheaper method of compensating for thermally-induced error. The results indicate that only a negligible amount of the total dimensional accuracy is sacrificed by adopting the proposed model instead of the traditional model.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Error Compensation, Dimensional Error, Machine Condition, Thermally-Induced Positioning Error.
Fatigue and Brinelling Evaluation of ASME Extraction Pressure Vessel Closure with Locking Ring
by A. M. Senthil Anbazhagan, M. Dev Anand
Vol. 5 n. 5, pp.
1013-1019
Abstract - Closure used to close and open the pressure vessel comes in special type of vessels instead of the fixed dish heads. This type of vessel design purely depends on the process and maintenance requirements. Closures may be in different thicknesses, dimensions and materials according to the requirements. The design of closure in the vessel head area is subjected to mechanical and hydrostatic loads. Need of this work accounts to the often failures of closures in the oil, gas, natural chemical product production industries due to the insufficient design, over pressure loading during hydro test and over mechanical loading during operation. Estimates of fatigue and brinelling were obtained from the finite element analysis from the range of work hardening plasticity. Comparisons were made with the outputs taken from the finite element analysis for the range of loading conditions, vessel and closure geometry and its shape. Generally it is found that although there are significant variations between the different finite element solutions, satisfactory estimates of fatigue and brinelling that are most conservative are obtained when the reference stress produced is adopted. In this paper the evaluation of fatigue and brinelling for 300 Liter High Strength Steel TYPE-17-4PH pressure vessel closure with locking ring is discussed. The reasons for the failures were studied. New design methodology and recommendations are suggested based on the analysis with respect to the requirements of ASME.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Brinelling, Finite Element Method, Fatigue, Failures Vessels.
The Modeling of the 2D Continuum with Non-linearities
by Jiří Podešva
Vol. 5 n. 5, pp.
1020-1025
Abstract - The modeling of the textile fabric is an interesting area of mechanical problems. The subject of modeling can be a several types of fabric bags, either prismatic or flat. The reason for modeling is to investigate the deformation of the bag, the stress state in the material and the total volume of the full bag. The modeling bears two problems. First is the geometric non-linearity. Because the stiffness is consequent on the deformation, the mechanical behavior depends on the deformation. The solution must be performed in iterative cycles, during which the stiffness matrix is updated in every solution step with respect to the calculated deformation. The geometric non-linearity is one of the typical problems of non-linear static and the solvers have tools for iterative solution. The second problem is “the first step problem”. The stiffness is consequent on the curved shape of the fabric. In the first step, when the model of the fabric is flat, it gives the zero stiffness. For this reason the solution of the first step can not be found. The paper demonstrates a kind of trick for “the first step solution”.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Finite Element Method, Fabric Bag, Discretization, Non-Linearity, Large Deformation, Newton-Raphson Approach.
Flying Qualities Estimation Methods for Small Unconventional Aircraft
by P. Hospodář, P. Vrchota, A. Drábek
Vol. 5 n. 5, pp.
1026-1038
Abstract - This article describes a methodology of the aerodynamic calculation and experimental measurement, which leads to determination of flight conditions within design of small unconventional aircraft. The first part contains the application of various types of computational methods to determine the aerodynamic characteristics. The results serve as the source material for the flight qualities determination. The second part describes validation and evaluation process. The data obtained from calculation, wind tunnel testing and flight tests were compared with special focus on flying qualities determination. Individual types of methods were step by step applied on the development of the small unconventional aircraft. The various stadium of the aircraft design were considered. The handbooks methods used in the preliminary design through the “simple” panel methods up to the advanced CFD methods. These advanced methods can be used in the final part of the geometrical design. This procedure reduces time and financial demands on the development. Second part is devoted to the validation of the computational results. The wind tunnel results and data from flights tests were used as a baseline. Two aspects were considered during evaluation of obtained results. One aspect takes into account flying qualities where the frequency and the damping are determined by the calculation of eigenvalues of the nonlinear model. Another aspect allows obtaining the complex view and the possibilities of the various methods which can be applied in the individual phases of the aircraft design from the point of view of the aerodynamics and the flight dynamics.
Copyright © 2011 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Flying Qualities, Aerodynamic Derivatives, CFD, Flight Testing, Wind Tunnel.
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