Iraqi journal of mechanical and material engineering

The effect of the particle size (dp) and the fluidized velocity investigated Experimentally and
theoretically for different values of heat flux thermal behavior in gas-solid fluidized bed was done
with time.
In this work three different particle size was employed (450,650 and 850 m µ ). The fluidizing
agent was air at different velocities in the range of (2-2.8 m/s). The rig provided with a horizontal
heating tube with outer diameter of (3.175cm) was heated eclectically with different power supplies
(80,240,350 Watt).
Presented mathematical model one dimensional unsteady includes energy, continuity, and
momentum equations for each of two phases. In order to solve the foregoing equations in a
numerical way, the discretization method based on control volume procedure has been used the
computer code (FLBD) which is written with mathlab 2008.
The results show that the temperature distribution along the packing height decreases with
increase particle size and the heat flux represents as the temperature increases as the air velocities
increase with time. Compared the experimental and theoretical results and the comparison is a good
agreement.

Soot particles emitted from diesel engines to atmosphere pollute the environment air because
many hydrocarbons known for their cancerous properties adsorb on its surfaces during the
combustion processes of diesel fuel.
These soot particles have very small diameters (less than 2.5 µm) and easy enter with air to
the human respiratory system during the inhalation process. In order to control of soot emitted from
four stroke, direct injection, air cooled and single cylinder diesel engine we executed two important
parts: (1) Rate of soot mass emitted from this engine was measured inside the passageway of
exhaust gases. One of the gravimetric methods for soot mass measurement in combustion systems
was developed to measure the rate of soot emitted from diesel engine. (2) The rate of soot emitted
from the engine was treated in a laboratory scale. Different diesel soot mass patterns were prepared
according soot mass measured in limited time interval at different engine loads, and then the soot
oxidation rates were studied using linear heating and isothermal heating inside the electrical
furnace. The results of soot emitted measurements show that the rate of soot emitted significantly
increases and reaches, at high engine loads, to 0.4533 mg/min because of highly reduced in A/F
ratio. Then large amounts of diesel fuel inside the cylinder suffer from pyrolysis heating. The
results of soot mass treatment with linear heating show that the rate of soot mass oxidation is
significant at mid and high loads between the temperatures (500- 800 Co). It can be concluded, from
the results of soot mass oxidation at isothermal heating with different temperatures (600 Co, 700 Co,
800 Co), that the rates of soot mass oxidation at different soot masses (i.e. different engine loads) is
approximately equal 25 mg/min.

In this paper, the experimental estimation of the fatigue strength and the standard deviation
for the 35NCDV12 alloy steel have been found using the Staircase (up and down) method. The
specimens divided into two groups. The first group contains 15 non-chromium specimens and the
second group contains 15 hard chromium specimens. The thickness of the chrome is about (100 to
120 microns). The fatigue or endurance limit has been determined for each group and then
compared with that estimated from S-N (W hler) curve for the 35NCDV12 alloy steel. The results
show that the endurance limit of the chromium specimens is decreased to a ratio about 60 % from
those non-chromium specimens. This proves that the chromium plating increases the wear and
corrosion resistance of the metals and decreases the fatigue strength and endurance limit of those
metals. In addition, the results show that the staircase method is very useful testing compared with
S-N curve for estimation the endurance limit without a large number of specimens.

The fatigue crack growth ( FGG ) behaviour of medium carbon steel alloy under different
rest periods is investigated under room temperature and stress ratio R= -1 using replication
technique . This work examines the constant and variable amplitude torsional fatigue under
different time of rest periods . The short and long fatigue crack growth equations are obtained
experimentally . The average grain size diameter is 0.277 mm which separates between short and
long crack region. The main remarks can be drawn from this work are :
The fatigue life of specimens is increase by rest periods under constant amplitude tests . The factor
of increasing is about 1-12. While this factor becomes 1.75 – 8.7 times the predicted life for
variable amplitude tests. Rest periods generate strain ageing which in terms increase the total
fatigue life.

In this paper, the unsteady state heat transfer through the thermal energy storage system is investigated numerically by using finite difference method in order to study the optimum thermal design of the latent heat thermal storage. The present analysis takes into account the heat transfer in two dimensions for fluid, tube and the PCM. The conical shape of the PCM is examined here for different diameters depending on the cone angle (ψ). The results of the present study are compared with other study to confirm the accuracy. Results of a numerical case study are presented and discussed. The results show that the decreasing the value of (ψ) will increase the hot and cold fluids effectiveness\'s and the difference between the effectiveness (hot and parallel cold and counter cold) increased with decreased value of (ψ) in the negative range (ψ = -0.13 deg). The counter flow for the cold fluid produces higher effectiveness than the parallel flow for the cold fluid especially for the negative value of (ψ = - 0.13 - 0 deg).

BaTiO3, synthesized in polycrystalline form, using stoichiometric mixture of oxide with
traditional ceramic technique and characterized by X-ray diffraction, tetragonal structure of
prepared powder were found. Moreover, particle size of ceramic powder determined using laser
particle size analyzer. The particle size distribution was found in the range (0.427-3.195)µm. The
epoxy ceramic composite system was prepared. BaTiO3 with content 10%, 20%, 30%, 40%, 50%
wt and 60% wt. respectively used as filler. Permittivity of the composites was investigated at
frequencies from 2KHz to 5 MHz The dielectric loss tangent (tanδ) was determined as a function of
frequency, compositions. It was found that the weight percent of BaTiO3 filler in ceramic/epoxy
composite effect on the dielectric properties. At low frequencies, BaTiO3/Epoxy composites have
much higher dielectric constant. Dielectric constant increases considerly with the addition of
BaTiO3 fillers, however, the higher conductivity of BaTiO3 than epoxy lead to an increase in ac
conductivity with increases BaTiO3 content, the increase in both properties was attributed to the
presence of the high permittivity ferroelectric phase

In this study grey cast iron welded by arc carbon method for two state: first the sample welded
immediately, second the sample preheating to 500 oC for samples of weld Region and heat affect
zone HAZ then cooling in different media ( air , dry sand and furnace) after test we found that
decreasing in hardness and tensile strength, when the cooling rate decrease than that of cooling in
the air, microstructure located on the surface of the weld sample convert to Martinsite Phase ( M ),
For the sample which cooling in dry sand and furnace, the hardness was less because of decreasing
cooling rate that made less changing in microstructure. It was also found that the decreasing in
hardness when preheating for sample and increasing in tensile strength led to obviation growth in
grain size resultant partial decomposing for perlite that led to improving toughness and Impact
strength.

The object of this work is study the thermal behavior for building roofs which made
from 150 mm concrete and cover with different materials instead of concrete roofing tiles ( gray
color ) at Baghdad city ( 33.2° N) ,its found that the concrete roofing tiles which painted by white
color gave 35 % saving value when compared with that energy consumed ordinary tiles (before
painted) while put the plastic tiles over that tile gave %28 saving value, and used the concrete
roofing tiles which contained 8 mm insulated materials with fiber glass screen gives %27saving
value and that tile is less weight.

In this study, effect of temperature, aspect ratio, number of layers and boundary conditions on
critical buckling load of composite laminated plate was investigated numerically. Six different
boundary conditions: (SSSS, SSFC, SSFS, SSFF, SSCC and CCFF), three temperatures (40C, 60C
and 80C) and four aspect ratios (1, 1.3, 1.5 and 2) would consider. These variables were analyzed
with different types of laminated plate (unidirectional, cross - ply and angle - ply). The thickness of
the plate was changed by increasing the number of layers.
The results showed that in the case of (a/b = 1 and θ = 0), and the temperature changed from
(40C) to (80C), the maximum value of critical buckling load dropped by about (53 %) for (CCFF),
while the minimum value of critical buckling load dropped by about (63 %) for (SSCC).
Also, it was found that the maximum value of critical buckling load dropped by about (60 %) at
the ply orientation (0/0) and (20/-20) at a/b = 1 and CCFF, while the minimum value drops by
about (64 %) at the ply orientation (0/0), a/b = 1 and SSCC as the temperature changed from 40C to
80C.

In this search the effect of silicon additions on the corrosion and dry sliding wear
behavior of (Cu+13wt%Al+3.8wt%Ni) shape memory alloy have been studies, alloys prepared by
powder metallurgy in two case based alloy after sintering treatment at temperature 850 for 6hr
and alloys after addition silicon as (0.4 , 0.8 wt%Si).Corrosion test based up electrochemical by
drawing the polarization curves method (Tafel) in salt solution (3.5wt%NaCl).A Dry sliding wear
has been studies based on pin on disk at a constant load, constant velocity and constant distance of
sliding with various sliding time. The result shows when the silicon content increase the corrosion
resistance of alloy increases also the dry sliding wear resistance of an alloy increases .

Field research confirmed that the maintenance activity equal to the importance of productive
activity
At the same time is not seen as purely a work of engineering, but among the activities of
administrative and engineering, economic, because it aims to achieve a better exploitation of factors
of production of basic materials, machinery and work Production Elements in order to reduce
production costs next to maintain the specified quality standards for the finished products.
That the calculated requirements best Perfects the elements of major maintenance (labor - raw
materials - labor - costs) will be reflected certain to increase the amount of production per unit time
and improve product quality by reducing the rates of damage during production and reduce the cost
of manufacturing, from here it is clear that interest in conservation and the adoption of systems and
advanced studies for planning effectiveness factor of the key factors for achieving the goals of
industrialization and improve the indicators of profit on the whole level of productive activity for
any manufacturing facility, and therefore we can through this research to achieve the following
advantages : - Utilization of production capacity available to the most efficient. -Managementof maintenance efficiency target. - Improve the indicators of profits through control of the cost elements of the search. - Find elements are indicators of the operational efficiency of the facility. - Reduce accidents and injuries during the implementation stages of production for the manufacture
of specific goods.

High-speed machining (HSM) has emerged as a key technology in rapid tooling and
manufacturing applications. The present work studies the effect of cutting parameters (cutting
speed, feed and depth of cut) in turning process applied on C-60 steel using multi- coated carbide
cutting tools at high cutting speeds. The influence of cutting parameters on a cutting forces, tool
wear and surface roughness are analyzed. The importance of orthogonal force components to
surface finish and tool wear are explored. The results show that cutting forces has a very strong
correlation with surface finish and that increased spindle speeds lead to far superior surface finish
. Tool wear measurements demonstrated the capability of such coated carbide tools in turning steel
with reasonable low tool wear (i.e. high tool life). Forces measured resulted in relatively low values.
The cutting component (Fc) is the largest of all. For the different cutting conditions studied, the feed
rate has the greatest influence on force and tool wear.