Journal of Theoretical and Applied Mechanics
Volume 38, Number 4, 2008
Fakher
Chaari, Mohamed Riadh Letaief, Mohamed Haddar
Dynamics of
Mechanical Systems Research Unit,
BP 1173 -
3038 –
e-mails: fakher.chaari@gmail.com, riadh.med@gmail.com, mohamed.haddar@enis.rnu.tn
Dynamic behaviour of thin rimmed in
Abstract. In this
paper, a dynamic model of a gear system composed of an external and an internal
gear is developed. The finite elements method is used to calculate the gearmesh
stiffness which is time varying and considered to be the main source of
excitation source of the system. This stiffness is computed for various cases
of the internal gear design. The rim thickness, the shape and the fixing mode
are varied. It is shown that this design affects considerably the evolution of
the gearmesh stiffness and the dynamic response of the system. Lower vibration
levels are observed for certain design cases.
Key words: internal
gear, thin rim shape, gearmesh stiffness, dynamic behaviour, rim fixing.
Angel Baltov
Akad. G. Bonchev Str., Bl. 4, 1113 Sofia, Bulgaria,
e-mail: baltov@eagle.cu.bas.bg
Zemon Mroz
Polish
21, Swietokrzyska, Str., 00-049 Warsaw, Poland,
e-mail: zmroz@ippt.gov.pl
Hydrogen Embrittlement in Fe,Al intermetallics
Abstract. The one-dimensional model for
plastic behaviour of the Fe,Al intermetallics is proposed. Two cases are
investigated: hydrogen attacks by moisture and hydrogen attacks by pressure.
Experimental verification is presented. Some discussion about the possible
three-dimensional generalization of the model is done.
Key words: Fe,Al – intermetallics,
modelling, hydrogen embrittlement.
Aid
Laboratoire
LPQ3M BP 763,
Université
de Mascara, Algerie,
e-mail: aid_abdelkrim@yahoo.com
Z. Semari, A. Amrouche, G. Mesmacque
Laboratoire
de Mécanique de Lille, Université de Lille1, UMR
Villeneuve
d’ASCQ 59650, France,
e-mails: semariz@yahoo.fr, abdelwaheb.amrouche@univ-lille1.fr,
gerard.mesmacque@univ-lille1.fr
M. Benguediab
Département
de génie mécanique,
Université de Dj. Liabes,
Sidi Bel Abbes, 22000, Algérie,
e-mail: benguediab_m@yahoo.fr
Abstract. The
mechanical components generally work under cyclic stresses with varying
amplitudes during the lifetime. It is important in predicting fatigue life and
how to deal with the problem of fatigue damage accumulation. On the basis of
the data for material taken by Stress-Number of cycles at failure (S-N) curves
and mechanical properties of material studied, a new nonlinear fatigue damage
cumulative model is proposed, ultimate strength, loading parameters and the
effect of the loading sequence are considered. This model is connected to S-N
curve cycle by cycle to determine the lifetime of the material and to calculate
the damage indicator. The cycles extracted are counted by one of counting
cycles methods.
The recurrence formula of
fatigue damage was tested for four various spectra of block loading.
The obtained results by
this model are compared with the experimental results and those calculated by
the most fatigue damage model used in fatigue (Miner’s model).
Such model is in
agreement with experimental results. Moreover, the error is minimized in
comparison to Miner’s model.
Key words: damage indicator, random loading,
block loading, random block loading.
M. Elajrami, M. Benguediab
Laboratory
of Material and Reactive Systems,
Department
of Mechanical Engineering,
e-mail:
eladjrami_mohamed@yahoo.fr
G. Ronald
This analysis is done
according to the plate ligament
and the hole edges by using an
uniaxial tensile load, the obtained results verified the phenomena of the retardment of crack initiation and propagation experimentally
observed.
Key words:
cold expansion, residual stress, rivet hole, stress concentration factor.
Department
of Mechanics Engineering,
BP
89, Cité Ben
M’hidi- Sidi Bel Abbes (22000),
e-mail: asbouchikhi@yahoo.fr
Evaluation axisymmetric analysis of thermal stress
residual near Fiber/Epoxy interface
Abstract. The finite element method is used to
compute and analyze the residual stresses particularly near the fiber/epoxy
interface, and these stresses need to be taken into account. An
axisymmetric model has been used for stress computation and analysis, in this work
two cases are considered by using an epoxy matrix with respectively glass and
carbon fibers with a different volume of fiber. Numerical
calculation results show that the stresses are important. The interface is
affected by thermal stresses particularly in the free edge. The normal
and shear stresses values have an influence on the behaviour of the composite
during service.
Key words: fiber/epoxy, thermal residual stresses,
axisymmetric model, energy release, Finite element method.
M. Khlif, N. Masmo
Analysis Laboratory of Electro
Mechanical Systems,
BP.1173. W. 3038
e-mail: khlifmohamed@yahoo.fr
V. Grolleau, G. Rio
Mechanical laboratory of Engineering
and Materials
Development
of a new testing method for polymer materials at high strain rate
Abstract. The increasing use
of polymeric materials in transport fields requires knowledge of their
mechanical behaviour at high strain rate to optimize the structures. The
particular behaviour of polymers, compared to metals, is characterized by low
Young modulus, weak density and viscoplastic behaviour, which make conventional
experimental test inoperative. The objective of this work is the development of
a dynamic tensile test reaching from 100 to 500 s-1 (strain rate)
based on the Charpy testing machine. The proposed test device is composed of an
instrumented bar and a sensing block for wave strain measurement to determine
the stress and strain on the tested material. The main objective consists in
studying mechanical behaviour of polymer material at high strain rate.
Key words: high strain rate, dynamic behaviour, shock, Hopkinson bar, sensing block.
K. Kazakov
VSU “L. Karavelov”, 175, Suhodolska Str., 1373 Sofia,
e-mail: kazakov@vsu.bg
ON THE RIGID BODY
MOTION RESTRICTION OF THE
Abstract. In this paper
the restriction of the rigid body motion of the Elastodynamic Infinite Element
with United Shape Functions (EIEUSF) in local coordinate directions, given as
ξ and η, is investigated. First, the concept of the construction of
the so-called EIEUSF united shape functions is given in brief. The mathematical
and mechanical aspects of the rigid body motion is demonstrated and discussed
in some details. Such a motion is impossible form mechanical point of view and
assures the EIEUSF element to be used as a special form of elastic boundary
condition. The conclusions can be treated as a part of the application of the
element.
Key words: Soil-Structure
Interaction (SSI), elastodynamic infinite elements, rigid body motion, wave
propagation.