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Home>Products>Journal and Reviews>I.RE.M.E.>Latest issue
International Review of Mechanical Engineering - September 2008 - Papers
International Review of Mechanical Engineering - Papers
Abstract - Engine is consider as one of the main source in producing noise and vibration in vehicle. Engine mount is used between chasis and body to control engine vibration. The goal of the paper is introducing optimization method to find optimum value for engine mount specification based on random vibration method. Changing design parameters such as: location of engine mount, angle of instal, stiffness and damping coefficient of engine mount causes to change Natural frequency and vibration transmissibility ratio of system. For this purpose, full vehicle finite element model include chasis, body, suspension system, tires, seats, glosses and engine of typical van vehicle is provided and the effect of engine unbalances harmonic is applied on the model as a Power Spectral Density (PSD) form. Finally, driver seat PSD acceleration in three direction (longitudinal, lateral and vertical) is obtained. Design parameters (location, stiffness, damping coefficient of engine mount) change in specific range to find best system response. Final result shows that driver seat PSD acceleration can be considered as an optimum choice. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Engine Mount Optimization, stiffness, damping, location.
Abstract - A detailed 3-D model of a seat–occupant system was developed to investigate the behavior of different body parts due to vertical and horizontal vibration. The human body was modeled as a system of rigid bodies, including head, neck, upper torso, pelvis, upper legs, lower legs and feet, connected at body joints modeled as torsional spring- damper systems. The seat was considered to be consisted of backrest and the seat cushion, each modeled as a rigid body with spring-damper units distributed over them. The vibration excitation was applied to the seat base through a translational actuator. The multi body dynamics method and Rung-Kutta numerical technique were employed to derive and solve the governing equations of the model, respectively. Results indicated that the main resonance frequency of the whole body and body parts were in the range of 4.5-5.5 Hz. For both vertical and horizontal vibrations, the maximum acceleration ratio occurred at head and the earliest and latest resonances were observed at pelvis and legs, respectively. With the increase of the vibration magnitude, the acceleration ratios decreased for both directions. When the hanging feet were fixed, the acceleration ratio increased in upper parts of body but decreased in lower parts. Removing the headrest had almost no effect on the resonance frequency of the upper part of the body, however, it increased the resonance frequency of pelvis. With stiffening the seat springs, the resonance frequency increased for all body parts. However, while the acceleration ratio decreased in upper parts of the body it increased in lower parts. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Human Motion, Whole Body Vibration, Multi Body Dynamics, Seat-Occupant.
by İ. Yıldız, V. E. Ömürlü, A. Sağırlı
Abstract -
This paper represents dynamic modeling
of generalized Stewart Platform Manipulator by Bond Graph method with a
new spatial visualization method and the state-space representation of
the dynamic equations of the system. Dynamic model includes all the
dynamics and gravity effects, linear motor dynamics as well as the
viscous friction at the joints. Following modeling of actuation system
and of main structure, unification of these two is accomplished. Linear
DC motors are utilized and are modeled as the actuation system. Since
overall system consists of high nonlinearity originated from geometric
nonlinearity and gyroscopic forces, resultant derivative causality
problem caused by rigidly coupled inertia elements is addressed and
consequential system state-space equations are presented. A spatial
visualization method is developed based on classic vector bond-graph
method, due to the lack of representing overall kinematic bonds of the
Stewart Platform Mechanism using classic vector bond-graph visualization.
Keywords: Stewart Platform, Bond Graph, System Dynamics, Spatial Kinematics, State-Space.
by L. T. Tenek
Abstract - The present study introduces a 3-node triangular shell element, the element ET15, for the analysis of plates and shells. The triangular element is a flat element with 6 degrees of freedom at each node; three displacements and three rotations. The formulation is based on the Explicit Finite Element Method (E-FEM). We apply to the triangular shell element 15 modes and derive the diagonal Modal Stiffness Matrix, the diagonal Modal Mass Matrix and the diagonal Modal Geometric Matrix. These matrices are then transformed to local and global coordinate systems. A distinct characteristic of the element is the edge application of periodic bending modes in terms of sinus and cosinus functions. Temperature is accounted as an initial load. Numerical simulations are provided. Due to the explicit theory, the triangular element is suited for efficient computer implementation. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Triangular shell element, modes, sinus/cosines functions, modal matrices, computing.
by R. Soltani, D. Kerdal, J. P. Jaspart, B. Nasser
Abstract - The knowledge of the prying action is no doubt essential to the understanding of the response of the idealised bolted steel connections or a tension region in beam to column steel connections.This paper presents part of the numerical results of a study devoted to the analysis of the amplitudes and the location of the normal pressure distribution to quantify the effective line of action of the prying force in idealised bolted steel connections. The elastoplastic response, up to the ultimate state, was analysed and aspects relative to prying forces, stiffness, strength and bolt loads were reviewed and a thorough study was made to provide some useful and relevant information in order to improve the state of the current knowledge. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords: Isolated, Bolted, Steel, Connections, Contact Region, Amplitude, Location, Pressure, End Distance, Prying Force, Stiffness, Strength, Bolt Force.
Abstract -
The aim of this work is to
effect experimental investigations comparatively to numerical
simulations on superelastic shape-memory alloys (SMAs) and specially its
importance when this latter is reinforced by smart composite materials.
The obtained material is then a special kind of “smart materials” whose
dimensions change due to temperature variations depending on structural
phase transition. Copyright © 2008 Praise Worthy Prize S.r.l. - All rights reserved
Keywords:
Smart materials, Shape memory alloys, Phase transformations, Finite
elements method.
by S. Sghaier, M.
Ben Tkaya, S. Mezlini, H. Zanhouani, Ph. Kapsa Abstract
-
In the present work a multi-ball-burnishing tool was
used to improve the surface roughness and the residual stress of 42 Cr
Mo4 steel. The burnishing process was carried out with several tool
passes. The surface roughness and residual stress after burnishing
process have been analysed. A scratch test was used to study the
influence of burnishing treatment on abrasive wear resistance. Different
scratch loads have been used in order to take into account the
subsurface behaviour of burnished flat specimen. A quantitative and
qualitative study has been developed. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Burnishing, Wear, Abrasion,
Scratch. by A. Elazzizi, A.
Belalia, A. Benamar, A. Maghraoui Abstract
-
We propose in this work, an
experimental study of influence mode of polishing on the tribological
parameters (coefficient of friction and residual stresses) and surface
quality of nonallied steels. Work was undertaken on samples which are
polished mechanically and others polished chemically, which will be
subjected to tests of dry friction using a tribometer pawn-plan
(ball-disc) in order to have the evolution of the coefficient of
friction; concerning the residual stresses developed during the dry slip
on the track of the wiper (ball 100Cr6 out of tempered steel) the tests
were carried out on an X-rays diffraction machine. While basing itself
on analysis method of data (Correspondence analysis) which will make
calls with the concept of profiles corresponding to the regrouping of
alloys according to their chemical composition and in element of
resemblance, these data will be then subjected to a factorial treatment
calling upon metric CHI-DEUX (χ2) which preserves better
probabilistic nature of this problem. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Coefficient of friction, dry
contact, mode of polishing, nonallied steels, residual stress.
Abstract
-
The influence of material properties on the behaviour
of edge waves (Rayleigh-type waves) in thin semi-infinite orthotropic
media is studied in the paper. The properties of these waves differ when
a given material is a laminate, isotropic medium or slightly anisotropic
crystallic medium on one hand or a crystallic structure with strong
cubic orthotropy on the other hand. The formulas for displacement
components and the frequency equations have been derived for both types
of material. In the first case, the Rayleigh edge wave properties are
qualitatively similar to those known from isotropic media while in the
second the exponential decay of displacement amplitudes with the depth y
is attended by their harmonic oscillations around the y. The transition
between two types of considered materials is studied and clearly
illustrated by an example of hypothetic material. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Rayleigh edge waves, elastic
orthotropic material, plane state of stress.
Abstract
-
This paper presents finite elements simulation of
frictional, elastic- plastic contact between two cylinders as well as a
cylinder and a flat surface. Some deterministic analytical approaches
have also been proposed to approximate the roughness of surfaces and
provide valuable numerical information. The results of theoretical and
finite element solutions have then been compared with those of Hertz
theory. The comparison shows that plasticity produces qualitative
changes in the distributions of local pressure in the contact. The
roughness of surfaces is another important parameter that alters the
contact stresses. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Contact mechanics; Elastic-Plastic contact, Rough surfaces, Piecewise
parabolas; Hertz theory.
Abstract
-
Achievement of assumed time of a powered
roof support unit advance depends on the ram force. Real value of this
force is determined by the parameters of the hydraulic supply system of
the powered roof support. Basing on the results of the flow coefficient
measurements in the most frequently used components of the hydraulic
supply system of the powered roof support, the characteristics of the
system is analysed. The impact of particular components of the system on
the value of the flow coefficient is determined for selected hydraulic
systems. For some configurations of the hydraulic supply system, the
impact of their characteristics on relative advancing force, defined as
the quotient of the advancing force value, determined for the assumed
time of operation and rated value of the advancing force, is presented.
On the basis of the conducted analysis, a criterion for an assessment of
the hydraulic supply system condition is suggested in the aspect of the
required advance rate of the roof support. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Powered roof suport, Supply system , Advancing load.
Abstract
- This paper analyzes quantitatively
and qualitatively the wear behavior of copper alloys in the presence of
friction and wear. These alloys are obtained by different elaboration
processes, including, gravitational casting, stamping, free-cutting and
casting under pressure. Different solicitation conditions are studied
using the pin-on-disc configuration. The main objective of this study is
to analyze the interaction between the elaboration process and the wear
behavior of leaded brass alloys. It is found that the elaboration
process by gravitational casting presents the highest wear resistance. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Brass, Elaboration process, Friction, Wear.
Abstract
-
The paper presents investigation of a viscotic clutch
with an electrorheological fluid working in a transmission system.
Experiments for the viscotic clutch were made on specially prepared test
rig. A mathematical model of unsteady–state motion of the transmission
system with the viscotic clutch was created on the basis of the
rheological characteristics of electrorheological fluid. The model
equations have been solved numerically with the Runge–Kutta–Gill
integration method. Next, theoretical and experimental results were
compared and discussed. In conclusion it was stated on the basis of a
verification procedure that the average relative modelling error was
less than 7 percent. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Viscotic
clutch, Electrorheological fluid, Transmission system. Abstract
-
The work presented in this paper consists in an analysis of interaction
effects between an external laminar air flow and a porous medium. We are
interested to these effects of interaction between the two mediums by
means of intersection of two computer software; one characterizes the
external flow and the other the porous structure. The results presented
are related to the space-time evolution of convective heat and mass
transfer coefficients, and the surface temperature. Obtained results are
in good agreement with those of the literature. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Porous Media, External Flow, Heat and Mass Coefficients, Surface
Temperature.
Abstract
-
This paper concerns the combustion in a reactive
packed bed of oil shales grains. In order to predict impact of many
parameters on fixed bed combustion of Timahdit oil shales (Morocco), a
transient one dimensional numerical tool was designed. The possible
thermal disequilibrium between solid and gas phase revealed in previous
studies has been treated using a two phases heat balance equation, one
for the gas and the other for the solid. Chemical analysis coming from
series of experiments performed in Rapsodee Lab. (Albi, France) were
used to determine a coal model considering pyrolysis producing char
which is oxidized using the oxygen conveyed by the air flow. The
sensitivity of the model to the speed injection is analyzed in this
paper. The development of a 2D numerical tool will be also presented to
show the importance of thermal heat lossesexisting on the walls and
their consequence on the reactive front propagations. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Combustion, porous media, non local thermal equilibrium.
Abstract
-
In this paper, the acoustical
absorption of sandwich plates with perforated material, for normal
incidence wave to layers, is studied by using the transfer matrix
method. The effect of acoustical, mechanical and geometrical parameters
of the plies is analyzed. In the first part, the results of the
acoustical absorption coefficient for a perforated plate are compared to
those of fibrous open perforated material. In the second part the
influence of the addition of skins on both sides of the layer is
studied. The third part relates to the study of sensitivity of various
parameters of a sandwich plate in perforated material. Finally, the
effect of the number of reasons is studied. The obtained results are
compared with an analytical and experimental results found in the
literature. This leads to conclude about the acoustical performances of
the sandwich plates with perforated material. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Acoustic, absorption, transfer Matrix, composite stratified, sandwich
plates, perforated material.
Abstract
-
In the continuous casting process, the mould region is an important
mechanism to improve steel quality; however its major role is the
setting of cast product form and to ensure a formation of a sufficiently
thick solidified shell to contain the molten metal at the exit of the
mould. The two-dimensional, steady state solidification model in the
mould used the cooling intensity method based on the finite volume
software FLUENT is presented. In this paper, a computational
solidification model is applied to investigate the effect of cooling
intensity on isocontours field distribution in mould region. Thereafter,
to predict the impact of the cooling intensity on the solidification
process of the continuous casting. Copyright © 2008 Praise Worthy Prize S.r.l. -
All rights reserved Keywords:
Continuous casting; Numerical model; cooling intensity;
solidification process; isocontours distribution. |
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