### Contents of Journal of Mechanical Engineering *63,* 3 (2012)

TONDL, A. PUST, L.: On the phenomenon "Parametric anti-resonance" 125
KOMPIŠ, V., MURČINKOVÁ, Z., FERENCEY, V.: Computational simulation
of composite materials reinforced by fibres with large aspect ratio 139
JIN XU-XING: Optimum synthesis method of mechanical press driven by
non-circular gears 155
ELBASHBESHY, E. M. A., EMAM, T. G., SAYED, E. A.: Effect of pressure
work on free convection flow from a vertical circular cone with variable
surface heat flux 169

# Abstracts

###
On the phenomenon "Parametric anti-resonance"

A. TONDL, L. PUST

The aim of this contribution is to present a survey of the main research
results dealing with the phenomenon "parametric anti-resonance" and to stimulate
the interests of designers for its application in engineering practice especially in
machinery and for devices where vibrations are undesirable for the safe run. It is
interesting that this phenomenon can be used for vibrations suppressing for all
kind of excitations, i.e. not only externally, but also for self-excitation and
undesirable parametric resonance.

###
Computational simulation of composite materials reinforced by fibres with
large aspect ratio

V. KOMPIŠ, Z. MURČINKOVÁ, V. FERENCEY

1D continuous source functions - fundamental solutions and their derivatives located
along fibre axes are used to simulate the interactions of matrix and reinforcing elements in
composite materials, when the primary field is a scalar function (e.g. temperature in heat
conduction) or a vector function (e.g. displacement in elasticity). The inter-domain continuity is
specified in discrete points on fibres boundaries. Intensities of the source functions are
defined by 1D NURBS and computed in LS sense in all fibres. The inter-domain continuity
equations have to be completed by balance equations (energy, equilibrium, etc.) in order to
obtain temperature, displacement, etc. in the centre of each fibre. Gradients of displacements
(strains) and temperature are supposed to be constant in cross-sections of the fibres and are
computed iteratively by considering them to be linear along fibres in the first step and both
the values, in the centre of the fibre and its change along the fibre axis, are computed in the
next steps. Material of both matrix and fibres is assumed to be homogeneous and isotropic.
Three numerical examples giving two fibres overlapping in some length in infinite matrix
show the numerical behaviour of the problem for heat conduction.

###
Optimum synthesis method of mechanical press driven by non-circular
gears

JIN XU-XING

A new type of mechanical press which has a crank-slider mechanism and a pair of non-circular
gears is presented in this paper. The crank is attached to the driven gear, so that the motion law of the
slider is determined by the non-\linebreak
-circular gears, and the displacement curve of the slider can be easily
changed to meet different processing requirements, which is necessary for the multi-variety and
small batch manufacturing.

The purpose of this study is to achieve excellent motion characteristics of the press; firstly, a
quintic polynomial curve is suggested for defining the desired motion of the slider. Then, an optimal
method is proposed to obtain the pitch curves of the non-circular gears, the object function and
constraints for optimization are discussed and suggested to obtain feasible design. Finally, an
example is introduced to illuminate the press performance; the results demonstrate that the
optimum synthesis method is effective.

###
Effect of pressure work on free convection flow from a vertical
circular cone with variable surface heat flux

E. M. A. ELBASHBESHY, T. G. EMAM, E. A. SAYED

The effect of pressure work on free convection flow from a vertical circular cone
with variable surface heat flux is considered. Similarity solutions for boundary layer
equations are found to exist when the surface heat flux is proportional to
*x*^{n} (where *x*
is distance measured from the leading edge). The governing system of partial
differential equations is reduced to a system of ordinary differential equations.
Mathematica has been used to solve such system after obtaining the missed initial
conditions. Comparison of numerical results is made with previously published results
under the special cases, the results are found to be in a good agreement. The solutions
are presented in terms of local skin-friction, local Nusselt number, velocity and
temperature profiles for values of Prandtl number, pressure work parameter and heat
flux gradient parameter.