Anbar Journal of Engineering Sciences

Composite laminate plates, fabricated by bonding fiber–reinforced layers, were
dynamically analyzed under different combinations of number of layers, type of cutout, hole
dimensions, angle of lamination and type of dynamic loading . This work was achieved by the
well–known engineering software (ANSYS). The toughness of composite plates was
evaluated in terms of the normal stress in the direction of loading at the periphery of the
cutout. The toughness was found to increase by increasing the number of layers, by setting the
lamination angle at around 40o
,by selecting hole dimensions to width of plate ratio of around
0.4 and by employing square cutouts or avoiding triangular cutouts. Also, composite plates
were found to be more strain-rate-sensitive in ramp loading, with least number of layers and
with triangular type of cutout.

Some mechanical properties of mortar (compressive strength and hardness) with
sawdust replacement of sand were investigated. Cubes of 50 mm × 50 mm were prepared,
the compressive strength tests were done for a replacement levels ranging (5, 10, 15, 25, 50,
75) % by volume a reference mix were also prepared for comparison this test was done after
7, 14, and 28 days while hardness test were done after 28 day for a replacement levels (0, 5,
10, 15, 25) % by volume.
Result showed that the compressive strength of the specimen were decreased with
higher sawdust content, hardness values were decreased slightly in the replacement levels 0,
5, 10 % while the values began to decrease noticeably in the replacement levels 15 and 25 %
the hardness values were (59, 57.5, 56, 47.77 , 45.2) N/mm2
respectively

One way of obtaining information about reliability of units is to accelerate their life by
testing at higher levels of stress (such as increasing elevated temperatures or voltages).
Predicting the lifetime of a unit at normal operating conditions based on data collected at
accelerated conditions is a common objective of these tests. Different models of accelerated
life testing are used for such extrapolations. Two statistical based models are widely used:
parametric models which require a prior specified lifetime distribution, and nonparametric
models that relax of the assumption of the life time distribution. The proportional odds model
is a nonparametric model in accelerated life testing based on the odds function and show that
it gives a more accurate reliability estimates than proportional hazard model. This paper will
concentrate on the models of proportional odds nonparametric accelerated life test for
reliability prediction

This research presented a strategy for designing a particular set of surfaces, obtained by
the technique of cross-sectional design. The surfaces considered were formed by sliding a
Bezier curve (profile curve), and also this research describes an automatic procedure for
selective identification of sampling points in reverse engineering applications using
Coordinate Measurement Machine.
In addition, Matlab program have been used in the present work so as to plot the curve
sections of the surfaces using transformation matrices. UGS program have been also used to
connect the sections that designed in Matlab program to get the final shape of the proposed
surface. It can be concluded that the whole steps task which built in the present research can
be programmed in a single block of the part program that’s from it can be create any curve or
surface at minimum designing time.

This research presents a mathematical model of feed-interval scallop height, where in a
machined surface there are two types of scallop height, the pick(path)-interval scallop and the
feed-interval scallop. The pick-interval scallop is generated by the finite pick offset between
the successive cutting paths, while the feed-interval scallop is generated by the finite
increment between the successive tooth feeds. New model that describes and predicts the
geometric generating mechanisms of the feed-interval scallop height have been derived using
torus cutter which is commonly used in multi-axis milling machine. The machining
parameters (effective tool cutter radius, feed per tooth and the magnitude of tool axis
inclination angles) have been considered in theoretical and experimental work to study the
effect of these parameters on this type of scallop height.
From theoretical and experimental work it was found that at high-speed machining, the
feed-interval scallop is more important to the surface roughness than the path-interval scallop,
and the feed-interval scallop is very sensitive to the tool-axis inclination angle. The feedinterval scallop height decreased sharply and quickly within a few degrees of the tool-axis
inclination to the normal workpiece surface. In general, an inclination angle equal to 15o
is
good enough for all tool diameters used in the present work, namely (6,8,10 12 mm).

In this paper, the effect of using the strengtheners on the stress and deflection under
the effect of a certain weight falling on plates made of aluminum alloys (Al Mg3)has been
studied. The study was carried on through two aspects; experimentally and theoretically;
theoretically by using (F.E.M LS. DYNA) program. After comparing the theoretical aspect
and experimental aspect, greatly- close results at point of contact were found out, as follows:
When using one strengthener, the stresses reduce by (14 %) and the deflection by
(70%) with comparison of without stiffener case .When using two strengtheners at the ends,
stresses reduce (77%) and the deflection (65%) .When using two strengtheners 8 cm apart,
stresses reduce (56 % ) and the deflection ( 18%) . When using two strengtheners 4 cm apart,
stresses reduce (60 %) and the deflection (31%)

Better understanding the innovative process of renewable energy technologies is
important for tackling climate change. Concentrated solar power (CSP) is a method of
electric generation fueled by the heat of the sun, an endless source of clean, free energy.
Commercially viable and quickly expanding, this type of solar technology requires strong, direct
solar radiation and is primarily used as a large, centralized source of power for utilities.
This study has focused on the feasibility of improving concentrating solar power (CSP) plant
efficiency, by manufacturing a diminished prototype. Three states were studied, coloring the
central target with a selective black color, fixing a reflector with arc form behind the target, and
using these two changes together. The results showed an improvement in the thermal storage
varied form month to month. The maximum stored energy was gained at August with increments
about 56.1%, 58.63%, 62.23 and 64.69% for ordinary target, black painting, using reflector alone
and black target with reflector together, respectively compared with stored energy for March.

The present work represents a two-dimensional numerical investigation of forced laminar
flow heat transfer over a 3-rows oval-tube bank in staggered arrangement with rectangular
longitudinal vortex generators (LVGs) placed behind each tube. The effects of Reynolds number
(from 250 to 1500), the positions (3 in x-axis and 2 in y-axis) and angles of attack (30o
and 45o
)
of rectangular VGs are examined. The study focuses on the Influence of the different parameters
of VGs on heat transfer and fluid flow characteristics of three rows oval-tube banks. The
characteristics of average Nu number and skin friction coefficient are studied numerically by the
aid of the computational fluid dynamics (CFD) commercial code of FLUENT 6.3. The results
showed increasing in the heat transfer and skin friction coefficient with the increasing of Re
number and decreasing the relative distance of positions of LVGs. It has been observed that the
overall Nuav number of three oval-tubes increases by 10–20.4% and by 10.4–27.7% with angles
of 30o
and 45o
respectively, with increasing in the overall average of skin friction coefficient of
three oval-tubes reached to 53% and 72% with two angles used respectively, in comparison with
the case without VGs.

An experimental and theoretical study has been conducted to determine the thermal
efficiency of a parabolic trough solar collector. The experiments have been performed during
winter and summer at Tikrit-Iraq. The solar radiation of Tikrit University was calculated
theoretically and a theoretical study was performed by using FORTRAN 90 program. The
dimensions and specifications of the collector were entered to the program to determine the
theoretical thermal efficiency. It has been found the experimental thermal efficiency of
collector is less than the theoretical one in percentage between (7-15) .So the increase in water
mass flow rate leads to an increase in the thermal efficiency, and there is no significant
change in thermal efficiency when the water mass flow rate becomes more than forty
kilograms per hour.