Iraqi journal of mechanical and material engineering

ABSTRACT This paper describes a unique solution of bouncing and pitching interactions, in which it plays an increasingly significant role in vehicle. While the behavior of vibrating system has motivated numerous experimental and numerical works, very few studies have been devoted to the case of vibration of car. This paper presents an investigation of bouncing – pitching effects, which is of strong interest for vibration of vehicle. The prediction of the natural frequencies in the car is thus a challenging task. This paper has a novel discussion of the dynamic behavior (natural frequencies and mode shapes) of vehicle and the relationships between the coupled natural frequency of the car. This work is theoretical and finite element method via ANSYS software study of dynamic performance of vehicle which is consists of two masses (body of car and tire). The paper deals with obtaining the vibration characteristic of an automobile analyzed as system without damping due to the effect of bouncing and pitching. The focus of the vibration analysis is to obtain the eigenvectors, and the corresponding natural frequencies of the system. Good agreement is evident between the theoretical and finite element method in which the discrepancy between the two methods is about 0.05% for bouncing and 0.2% for pitching model. Also, it can be deduced that the join between car and tire, the result of the natural frequencies is differed from that of the natural frequency for the individual one, in which the higher frequency is increased and decreased the less one.

A theoretical solution is presented for polymeric thick pressurized cylinder,
where material behaviour is described by the modified Von Mises criterion. The
solution is carried out using different values of Yc/Yt ratio to demonstrate their effects
on the plastic zone radius and on the radial and hoop stresses also on the residual
stress components.
The results is indicated that the influence of α ratio or (Yc/Yt) ratio on the
plastic zone radius and stress distributions is significant, and it can be shown that ,
when α ratio increases the plastic zone radius decreases , the value of α ratio has no
effect on the value and distribution of radial stress, and when α ratio increases the
level of the hoop stress increases in the plastic zone and decreases in the elastic zone
and the value of α ratio is directly proportional to the value of residual radial and
hoop stresses in the cylinder. A published finite element results give a reasonable
agreement with the obtained results.

This research aimed to study the effect of flame retardant material addition namely antimony trioxide (Sb2O3) on thermal conductivity of composite material consist of conbextra epoxy (EP-10) resin reinforced by chopped E–type glass fibers with density (600g/cm2) .The effect of different percents of antimony trioxide (10%, 20%,30%) on thermal conductivity was investigated by using Fourier equation to calculate the thermal conductivity coefficient (k) for this composite material before and after addition of flame retardant material ,where the thermal conductivity value improved after added trioxide where it change from(0.35 W/m.ºC) before added antimony trioxide to (0.4 W/m.ºC) after addition (30%) from oxide at temperature (50 ºC) which the best value from oxide additive .

This research aims to study the effect of quenching by oil with tempering at
180°C and 400°C on wear rate of 100Cr6 steel. A pin-on-disc technique was used to
measure wear rate at different loads and different sliding times with constant sliding
speed(2.199m\\\\\\\\sec)and the hardness of steel dise was 45HRC.
The results show that the wear resistance of the specimen quenched by oil and
tempered at 400°C was more than the specimen quenched by oil and tempered at
180°C.

This research aims to, first: to increased thermal insulation to conbextra epoxy
(EP10) by additive magnesium oxide (MgO) with (5 µm) particle size as a filler with
different Weight percentages (10%,20%,30%) to resin and study the effect of this
additive on thermal insulation of the resin . Fourier equation was used to calculate the
changing in thermal conductivity coefficient (k) for conbextra epoxy (EP10) before
and after addition of magnesium oxide ,where the results show improved thermal
insulation of the resin by reduced in thermal conductivity coefficient value after oxide
addition, and the value of thermal insulation will increase with increasing of additive
percentage of magnesium oxide, where it changes from (0.24 W/m.ºC) before added
oxide to (0.13 W/m.ºC) after addition (30%) from oxide at temperature (40 ºC) which
the best value from oxide additive. The second: to study the mechanical behavior of
the resin after reinforced it by the above weight percentage of magnesium oxide and
studied its effect on mechanical properties of the resin which included: impact strength
, tensile strength, and compression strength. It has shown an improvement in these
mechanical properties after reinforcement by magnesium oxide where the value of
mechanical properties will increase with increasing percentage of reinforcement.
Impact strength increased from(30Kj/m2) to (39Kj/m2), and tensile strength
from(60Mpa) to (74Mpa), and compression strength from(132Mpa) to (146 Mpa), for
reinforcing percentages 0% and 30% from magnesium oxide respectively.

This research was conducted following the process of coating by thermal spray flame
technology through the use of a mixture gas composed of oxygen and acetylene for the
purpose of obtaining a surface layer of ceramic coating on the surface of the medium
carbon steel type (AISI 1050), provides an increase in the surface properties of the
metal which is represented by wear resistance. The research carried out in three
successive stages, the first stage included the preparation of the surface of specimens as
well as the preparation of powder coating and analysis of chemical components of the
specimens and coating powders. While the second stage included the implementation of
the connector coating process (nickel aluminum) and coating the main (alumina) using
a flame spray coating process conducted in different ways for each specimen by change
in spraying factors, which included the surface roughness of the base specimens, the
temperature of the surface of the base specimens before the coating process, the distance
between the spray gun nozzle and the surface of the specimens and thickness of the
coating. The third stage included the testing of standard tests, which includes adhesion
test, check wear and roughness of different coatings in addition to a microscopic
examination of the successive layers of coat and surface basis.
It has been reached on the best variables that give the high adhesion and the lowest
wear rate, where the results showed that the increase of roughness from (0.85 m) to
(10.50 m) led to the low rate of wear by up to about (51%) more than half, The best
temperature of the heated surface of the foundation before the coating process to obtain
the lowest rate of wear and higher adhesion ranging from (200 C º) to (300 C º). While
the optimal distance between the spray nozzle and the surface of the specimen ranging
from (150 mm) to (200 mm) and thickness optimized for coating ranging from
(0.15mm) to (0.5mm) for the best coating with the lowest wear rate.

A theoretical study to calculate the performance of the turboshaft engine (TV3
117 MT), used to power the helicopter (MI17). It is clear that the engine works less
efficiently in a hot ambient especially during takeoff because the engine at takeoff
needs maximum power. The engine performance is also calculated after water
injection at compressor entrance. A new mixture (water and air), the dew point
temperature has also been calculated at compressor entrance and in every stage to
ensure that no condensation of water vapor is take place on the blades of the
compressor. To satisfy this aim the amount of water injection should not exceed
(0.8%) of air mass flow rate depending on the permissible payload of the engine.
The performance with water injection was calculated at different amounts of water
injection (0.2 %, 0.5 %, 0.7 %, and 0.8 % of air mass flow rate with constant
temperature (10 C0)).The results showed that an increase in the amount of water
injection leads to decrease in the mixture temperature and to an increase in the
specific heat at constant pressure.
The percentage improvement in the performance for the specific power, thermal
efficiency and specific fuel consumption at (Ta=55 C0) and •
m=0.8% of air mass
flow rate at the entrance of the compressor were (14.7, 12.6 and 11.3) respectively.

In this study Tungsten Inert Gas spot welding (TIG Spot ) is carried out for Al
Mg alloy (5052) with the overlap join for sheet of 1mm thickness. Welding process is
carried out at different welding currents and times at a constant arc length (1.6mm).
optimum welding conditions are determined depending on maximum shear force of
weld joint. Theoretical work is by using finite element method by utilizing program
(Ansys 5.4) to calculate thermal stresses in TIG Spot at welding currents
(80,100,110,120) Amp and welding times (6,7,8) sec.
The results showed that the best maximum shear force for welds was 2000N at
110Amp and 6sec. These result gives better distribution for thermal compressive
stresses through depth and diameter of spot weld. The comparisons between
computational results and experimented work from hardness measurement through a
cross section of spot weld has a good agreement.

This work represents an attempt to introduce further improvement or the properties
of theses coatings, although the (ZnNi) deposition is known to be an anomalous
electrodeposited process , where added Ceramic materials is (silicon carbide) ,with
very good mechanical properties .
Carbon steel samples were coated with (ZnNi) and (ZnNiSiC) particles with
different particles size of silicon carbide once microscale (73µm) and another
nanoscale (70100nm) .After electroplating, these samples were analyzed by Xray
fluorescent to confirm all the content for each alloy.

In this paper, Y2O3/Al–Si composites are prepared by squeeze casting process and
merit rating method is used to optimize the squeeze casting process parameters. A
wear rate and hardness tests were conducted and the density is calculated for the
resulted castings. The primary objective is to use merit rating method to find a better
group of parameters that give the good balance of high density and hardness with low
wear rate. The evaluated squeeze casting parameters are pouring temperature, die
temperature, and squeeze pressure. The experimental and analytical results showed
that the merit rating method was successful in determining the group of parameters
that give an optimum balance of properties. Also it showed that if the difference in
any property values among specimens is high, it can affect the selection process with
the importance sequence.

Fuzzy logic defines rules that determine the behavior of the system using word
descriptions instead of mathematical equations, fuzzy logic control algorithms can be
used to solve problems that are difficult to address with traditional control techniques.
In this research a fuzzy control strategy is proposed to control the stability of an crane
work. It is beneficial that the fuzzy logic concentrates on the significance rather than
the accuracy and the mechanism is applied without get in complex mathematics,
therefore the only important thing here is the stability. The results of the four case
studies indicate that the proposed control strategy is feasible with more simplicity and
acceptance.

This study examines the flow of water and air in a cross junction by fluent under
Ansys 12. Initially the problem will solve by using the less computationally intensive
mixture model, and then turn to the more accurate Eulerian model. In this study which
is using flow of water and air inside closed and vertical conduit as cross junction so
the flow is water and air as mixture in inlet of pipe and the mixture leaves the pipe in
three outlets as shown in Figure (1), also the phase of the air is assume to be bubble
flow, so the diameter of the bubble of air will be present. The slip velocity equation
need to solve since there will be significant difference in velocities for the different
phases. The study used solid work programme to work the figure and then export it to
fluent of Ansys. The study used the mixture model and Eulerian model to investigate
the distribution of air inside the cross pipe and the where of the effect of static
pressure inside the cross conduit for design. Also, the contour of velocity magnitude is
used to know the moving and distribution of the flow. The comparison between the
two model have happened to know the range of converge for results for two model.

NickelTitanium shape memory alloy (Nitinol or NiTi) is a fascinating material
for dental applications. In this work the alloy has been prepared by powder
technology and the effect of Mg and Zn additives has been studied on the corrosion
rate, in artificial saliva. Samples (without additives) were prepared using powder
mixture of 55 wt.% Ni and 45 wt.% Ti by blending in a ball mill for two hours, then
compacted at 800 Mpa, and then sintered at 950 oC for 9 hours under controlled
atmosphere (argon). The same approach was made for the samples with 0.1, 0.2 and
0.3 wt% of Mg and Zn additions. XRD test shows that the sintered samples are
consisting of two phase\'s martensite and austenite at room temperatures. From the
results: it was found Zn additives increase the corrosion rate while Mg additives
decrease the corrosion rate.

A Pin on Disc wear testing rig of variable sliding speed with varying load
and sliding time has been used in this research to measure the wear rate of the
carbon/epoxy composite specimens at dry and wet working conditions.
In this research the composite specimens made from the epoxy used as a
matrix and the carbon fiber with length ≤ 3mm and volume fraction (3, 6 & 9 vol. %)
as reinforcement.
The results show that the wear rate of composite specimens increase in
nonlinear relationship with increase the applied load, sliding speed and sliding time
and decrease in nonlinear relationship with increase the volume fraction of carbon
fiber.
The results also show that the wear rate for the epoxy reinforced by carbon
fibers for dry working conditions was higher than the wear rate for wet working
conditions. The maximum percentage reduction in wear rate was 30% for wet
working conditions and 18.5 % for dry working conditions at 9 % Vol. of carbon
fibers when compared with the neat epoxy.

In this work the mechanical properties of polymer composites reinforced with ceramic
particulates are investigated. The epoxy resin used as a Matrix material is Ep10 and the
reinforcement particulate materials are silica with particle size (5363)µm and alumina with
particle size (106150)µm ,and having weight fraction of 20%, 30% and 40% respectively.
Specimens of the matrix material and the six types of composite materials were subjected to
tensile, compression, bending, impact and hardness tests. Experimental tests results indicate
that the composite materials have significantly higher modulus of elasticity than the matrix
material. It was found that the enhancement in modulus of elasticity is directly proportional to
the weight fraction of reinforcement material and that alumina composites have higher modulus
of elasticity than silica composites with equivalent weight fraction .The highest modulus of
elasticity is that of the composite with 40 % alumina, which is 182% higher than that of the
matrix material. The tensile and bending strength of the matrix material were found to be
significantly higher than those of the composite material while composites with 30% and 40%
weight fraction reinforcement martial have marginally higher compressive strength than the
matrix material. Test results also indicate that material toughness, fracture toughness and
hardness of the composite materials are significantly higher than those of the matrix material.
The enhancements in these properties are found to be directly proportional to the weight
fraction of reinforcement materials. These properties of composites reinforced with alumina are
significantly higher than that of composites reinforced with equitant silica(quartz) content. The
highest material toughness, fracture toughness and hardness are that of the composite with 40
%alumina.