### Contents of Journal of Mechanical Engineering *57,* 2 (2006)

SUMELKA, W., LODYGOWSKI, T.: Substitute acoustic boundary
impedance conditions for boundaries with periodic geometry
in computer simulations of acoustic planar wave travelling 59
HAZEM ALI ATTIA: Hall effect on transient Hartmann flow and
heat transfer of a power-law fluid between parallel porous
plates under exponentially decaying pressure gradient 71
KIREITSEU, M., TOMLINSON, G. R., HUI, D., BOCHKAREVA, L.,
RONGONG, J. A.: Advanced design and modelling of nanoparticle-
-reinforced damping materials 95
ALTENBACH, H., NAUMENKO, K., PYLYPENKO, S., RENNER, B.:
On the free particle rotation in a polymer melt 112

# Abstracts

### Substitute acoustic boundary impedance conditions
for boundaries with periodic geometry

in computer simulations of acoustic planar wave travelling

WOJCIECH SUMELKA, TOMASZ LODYGOWSKI

In the paper the substitute acoustic boundary impedance conditions for boundaries
with periodic geometry are considered. The complex geometry of boundary is treated as
planar one with the equivalent impedance conditions obtained from the process of numerical
homogenization. The computer simulations used the finite element method (FEM) and all
analysis took into consideration the sinusoidal acoustic planar waves. Homogenized
boundaries significantly decrease number of degrees of freedom in acoustic analysis, what, in
many cases, is the only way to overcome extremely high hardware requirements.

### Hall effect on transient Hartmann flow and heat transfer of a power-law
fluid

between parallel porous plates under exponentially decaying pressure
gradient

HAZEM ALI ATTIA

The transient Hartmann flow of an electrically conducting viscous incompressible
non-Newtonian power-law fluid between two parallel horizontal non-conducting porous plates is
studied with heat transfer without neglecting the Hall effect. A sudden uniform and
exponential decaying pressure gradient, an external uniform magnetic field that is
perpendicular to the plates, and uniform suction and injection through the surface of the plates
are applied. The two plates are kept at different but constant temperatures while the Joule and
viscous dissipations are taken into consideration. Numerical solutions for the governing
nonlinear momentum and energy equations are obtained using finite difference
approximations. The effects of the Hall term, the parameter describing the non-Newtonian
behaviour, and of the velocity of suction and injection on both the velocity and temperature
distributions, as well as on the dissipation terms are examined.

### Advanced design and modelling of nanoparticle-reinforced damping materials

MAKSIM KIREITSEU, GEOF R. TOMLINSON, DAVID HUI, LIYA BOCHKAREVA, JEM
A. RONGONG

The focus in this paper is to provide a multiscale modelling and computational tools
towards the development of the next generation vibration damping
materials/systems that are light-weight, vibration and shock resistant. The research
work concentrates on an investigation related to theoretical and experimental dynamic
characterization of carbon nanotube-reinforced materials across the length scales. The
outcome of the research work is expected to have wide-ranging technical benefits
with direct relevance to industry in areas of transportation (aerospace, automotive,
rail), precise engineering and civil infrastructure.

### On the free particle rotation in a polymer melt

HOLM ALTENBACH, KONSTANTIN NAUMENKO,
SERGIY PYLYPENKO, BARBARA RENNER

For the reason of weight reduction nowadays in engineering
applications many load transmitting structures are of polymeric
materials and can be manufactured by injection molding. Their
mechanical properties can significantly be improved if the polymer
is reinforced by short fibers. From experiments it is known that the
fiber orientation is usually not constant. Already during the design
of structures it is necessary to predict the fiber orientation and
thereby the mechanical properties like stiffness and strength.
A fiber can be regarded as a rigid particle. One basic aspect
considering the motion of fibers in the polymer melt during the
injection molding process is their rotation. For a single particle
it is analyzed based on the laws of dynamics. The geometry of the
particle is defined, its tensor of inertia is assumed to be
transversally isotropic. Since friction with the medium must be
taken into account, a model is developed with which its influence on
the particle can be described. For this purpose a moment of viscous
friction is introduced.