Anbar Journal of Engineering Sciences

Numerical solutions are presented for mixed convection from an array of circular
cylinders embed in a saturated porous medium. The cylinders are at constant
temperature(isothermal) and arranged in a staggered tube bank. Both aiding and opposing
flow conditions are considered. Numerical calculations using finite difference method with
body-fitted coordinates have covered a wide range of governing parameters(i.e.,10 ≤ Re ≤
100, 0 ≤ Gr ≤ 400 and Pr = 0.7). Results are presented for streamline, isotherms and the local
and the average Nusselt number at different values of the governing parameters. The present
results are compared with previous theoretical results and show good agreement

This paper deals with a numerical investigation of natural convection of heat transfer
in a horizontal eccentric annulus between a square outer enclosure and a heated circular inner
cylinder.
The governing equations are expressed by the term of the stream function-vorticity
with dimensionless temperature. The body fitted coordinate system (BFC) was used to stretch
over the physical domain of the presented problem. The Poission's equation of stream
function is solved by successive over relaxation (SOR) method, while time marching
technique was the best choice to solve both vorticity and energy equation.
The results are presented for the streamlines and isotherms as well as the average Nusselt
number at different eccentricities and angular positions. Comparison with previous
theoretical results shows good agreement.

Free vibration analysis of a cracked cantilever beam with two types of additional
substructure attachment is investigated using ANSYS program. The cantilever beam is used
as a master structure with single substructure attachment in various locations (as 1-DOF mass
attachment and 1-DOF mass-spring attachment) with influence of crack in different location
and depths. The results for the changes of the natural frequencies of a cracked beam are
compared with the results produced by Vahit et al [1]. So the same geometrical properties
have been studied. In additional work a cracked beam carrying two types of substructure
attachment are compared with the results of the beam without a crack and with multi crack
depth. In all calculations the beam has a uniform cross-section and the crack was modeled by
reduction in the modulus of the beam. The reducing effects of the cracked beam on the
natural frequencies had been more apparent with the substructure attached to the beam in
different situations. The effect of mass-spring substructure is larger than the effect of the
attachment when modeled as mass substructure for the same mass, with 17% for the first
natural frequency and 2% for the second and third natural frequencies. The results can be
used to identify cracks in simple beam structure; cracks have a clearer decreasing impact on
the natural frequencies

In this study an attempt is made to develop a method of analysis dealing with a multilayer composite continuous beam , for linear material and shear connector behavior in which the
slip (horizontal displacement) and uplift force (vertical displacement) are taken into
consideration. The cross-sectional area for the beam consists of three layers varying in thickness
and shear stiffness. The analysis is based on a approach presented by Roberts[1], basically for
two layer simply supported beam, under uniform and point loads , which takes into consideration
horizontal and vertical displacement in interfaces. The analysis led to a set of eight differential
equations containing derivatives of the fourth and third order. A program based on the present
analysis is built using finite difference method using boundary conditions. A comparison
between the present analytical solution and previous studies shows close agreement. Continuous
composite beams are very important element in construction of high rise buildings , multi-story
frames and bridges, due to great advantages that can be obtained by using this sort of structural
elements, such as reducing the beam moments, suitable reduction in deflections. The model deals
with continuous beam consisting from three layers as a cross-sectional area with inter-layer slip.
The cross-sectional area consist of composite material including intermediate layer from
concrete and an upper and lower material with high strength in tension and compression ( i.e.
steel plates or steel beams )

The aim of current work is to investigate the tensioned composite plates with two types
of cutouts. Many industrial applications use composite matrix with reinforcement fiber to
obtain better properties. The objective of this work is divided into two parts, first the
experimental work covers the measuring of the normal strain (εx) at the edges of (circular &
square) holes that are perpendicular to the direction of the applied loads with different
number of layers and types of cutouts of composite materials by using strain gages technique
under constant tensile loads to compare with the numerical results. The second part is
numerical work, which involves studying the static analysis of symmetric square plates with
different types of cutout (circular – square). In static analysis, the effect of the following
design parameters on the maximum stress (σx), strain (εx) and deflection (Ux) is studied. This
part of investigation was achieved by using the software finite element
package (ANSYS 5.4).

The main objective of this study is to determine the effect of vortex generators on a
friction factor for fully developed flow of a fluid such as air. Longitudinal vortices can be
generated in a channel flow by punching or mounting protrusions in the channel wall. Such
vortex generators (VGs) can be classified into delta wing, rectangular wing, pair of deltawinglet and pair of rectangular winglet. These longitudinal vortices disrupt the growth of the
boundary layer and lead to enhance the heat transfer rate between the working fluid and the
conductor channel wall, but this enhancement is associated with increasing in a pressure
gradient along the axial length of the channel. So, the friction factor for fully developed air
flow in an equilateral triangular duct is investigated experimentally with Reynolds number
ranging from (31,000) to (53,000) and the size of the generators was kept constant for three
cases which are single, double, and triple pairs of delta–winglet type of vortex generators
embedded in the turbulent boundary layer for attack angle of generator of (30, 40, and 50 )
degree. The results show that the friction factor increases by about (43.5 %) when the angle
of attack is varied from (30 deg) to (50 deg) for the triple pairs case compared with the base
case (without VG)

An experimental investigation as well as nonlinear analysis is carried out in this paper
to study the behavior of polymer members (Epoxy & Polyester) under direct tension. The
ANSYS model accounts for nonlinear phenomenon, such as, Tension Softening Material
(TSM) and Enhanced Multilinear Isotropic Softening (EMIS) models. The polymer
specimens are modeled using PLANE82 element – eight node plane element – eight node
plane element, which is capable of simulating the failure behavior of polymer material
members. The intention of this paper is thereby to discuss the proposed softening models to
validate the complete Stress-Strain and Load-Deflection response of prismatic specimens
subjected to uniaxial tension. The outcomes from the verifications of both modeling
techniques have shown good agreement with the experimental results obtained from
literature

In this study an attempt is made to derive governing equations satisfying equilibrium
and compatibility, for multi-layer composite simply supported beam under blast loading ,
for linear material and shear connector behavior in which the slip (horizontal displacement)
and uplift force (vertical displacement) are taken into consideration. The analysis is based on
an approach presented by Roberts, which takes into consideration horizontal and vertical
displacements in interfaces. The model consists of a simply supported beam with three layers
having a cross-sectional area ,different dimensions and material properties. The analysis led
to a set of six differential equations containing derivatives of the fourth and third order. The
blast loading was considered as a function of time. Explosions have different effects
including blast, penetrations and fragmentation. The blast is the main effect which hits the
structure in short duration. Multi –layer composite construction is the best type of
constructions to resist the blast loading ; according to this , multi-layer composite
construction is used for air-craft and marine industries. Analysis of composite beam under
blast load , taking in consideration vertical and horizontal displacements, leads to six
differential equations , the load is taken as a function of time.

A new technique is presented by which lateral outflows of material , from an oblique impact
collision between wax projectile and a rigid surface , are collected to form a high speed single
jet. This jet has been shown to be capable of producing cavities in semi-infinite target of wax
in a manner similar to that produced in a hypervelocity impact situation. The produced jet
capability of penetration is found to be maximum at higher velocities of impact , lower values
of standoff and with projectiles having angle of obliquity in the range (β=20-25o
). A
preliminary theoretical model is also presented in an attempt to describe the process of jet
creation and jet characteristics. The present technique is proved to be promising in simulating
penetration of semi-infinite targets by the impact of high speed jet .