Iraqi journal of mechanical and material engineering

This paper present an investigation of the collapse load in cylinder shell under uniform
external hydrostatic pressure with optimum design using finite element method via
ANSYS software. Twenty cases are studied inclusive stiffeners in longitudinal and ring
stiffeners. Buckling mode shape is evaluated. This paper studied the optimum design
generated by ANSYS for thick cylinder with external hydrostatic pressure. The primary
goal of this paper was to identify the improvement in the design of cylindrical shell under
hydrostatic pressure with and without Stiffeners (longitudinal and ring) with incorporative
technique of an optimization into ANSYS software. The design elements in this research
was: critical load, design variable (thickness of shell (TH), stiffener’s width (B) and
stiffener’s height (HF). The results obtained illustrated that the objective is minimized
using technique of numerical optimization in ANSYS with optimum shell thickness and
stiffener’s sizes. In all cases the design variables (thickness of shell) was thicker than the
monocoque due to a shell’s thicker is essential to achieve the strength constraints. It can be
concluded that cases (17,18,19, and 20) have more than 90% of un-stiffened critical load.
The ring stiffeners causes increasing buckling load than un-stiffened and longitudinal
stiffened cylinder.

A study is reported of the laser cladding of a nominal composition of Ni 5 wt% Al on cold
rolled low carbon steel (0.16 wt% C), using a high power continuous CO2 laser. The severe
rolled microstructure of steel was changed considerably at the heat affected zones under all
specific energies. The cladded coatings showed the presence of ɣ solid solution and β
(NiAlFe) phases. Sound metallurgical bonding with absence of porosity and cracks was
observed between the substrate and the clad coat at specific energy higher than 80 J/mm2.
The ferrite and pearlite microstructure of the substrate was changed to martensite at the region
adjacent to the clad interface. It followed by large grains of austenite/ferrite and pearlite
(grain growth zone), fine grains of austenite/ferrite and pearlite (recrystallization zone) and
very small zone of relatively small change of cold structure (recovery zone). The last zone
was confirmed by micro hardness as a recovery zone.
This investigation confirms clearly the possibility of formation different structures of grain
growth, recrystallization and recovery at the laser heat affected cold rolled low carbon steel.
The observed results suggest the developing of a new technique to obtain tentative
functionally graded material.

Several studies have been made during the recent years to evaluate the plasma sprayed
yttria partially stabilized zirconia thermal barrier coatings but less attention were
undertaken on ceria-yttria stabilized zirconia. In this study, zirconia- 20 wt% ceria-3.6
wt% yttria thermal barrier coatings were produced by air plasma spraying deposited on
IN 738 LC superalloy substrate. The objective of this study is to analysis the distribution
of porosity, hardness and fracture toughness on the deposited coatings. Under optimum
plasma spraying conditions, it is dangerous to consider the mean values of hardness and
fracture toughness. The distributions of hardness and fracture toughness are highly
scattered. The Weibull distribution is the main parameter to describe the plasma sprayed
coatings hardness and fracture toughness.

Magnesium oxide (MgO) is regarded as a biocompatible material. A composite material from
MgO oxide prepared by mixing MgO powder with TiO2 (rutile phase) (2, 5, 10)Wt.% using
powder metallurgy technique. It is used to be bioceramic material. The compressed samples
were dried and sintered at (1200) ᵒC. porosity measurement showed that the porosity
decreasing with increasing TiO2% . X-ray showed the presence of Mg2TiO4 in the composite
structure of MgO with (5, 10)%TiO2 samples.
The mechanical study showed an increasing in compressive strength, hardness, wear
resistance and biodegradation resistance with increasing TiO2% content in the limit of used
percentage. The prepared composite material didn’t present antibacterial activity while
previous researches showed opposite result because of using nanoscale particle size of MgO.

This paper present an investigation of the collapse load in cylinder shell under uniform
external hydrostatic pressure with optimum design using finite element method via
ANSYS software. Twenty cases are studied inclusive stiffeners in longitudinal and ring
stiffeners. Buckling mode shape is evaluated. This paper studied the optimum design
generated by ANSYS for thick cylinder with external hydrostatic pressure. The primary
goal of this paper was to identify the improvement in the design of cylindrical shell under
hydrostatic pressure with and without Stiffeners (longitudinal and ring) with incorporative
technique of an optimization into ANSYS software. The design elements in this research
was: critical load, design variable (thickness of shell (TH), stiffener’s width (B) and
stiffener’s height (HF). The results obtained illustrated that the objective is minimized
using technique of numerical optimization in ANSYS with optimum shell thickness and
stiffener’s sizes. In all cases the design variables (thickness of shell) was thicker than the
monocoque due to a shell’s thicker is essential to achieve the strength constraints. It can be
concluded that cases (17,18,19, and 20) have more than 90% of un-stiffened critical load.
The ring stiffeners causes increasing buckling load than un-stiffened and longitudinal
stiffened cylinder

The free convection between two tilted adiabatic plates with centered heated horizontal
cylinder with attached plate fin was investigated experimentally and numerically. The
experimental rig constructed from vertical adiabatic was filled with air plates with aspect
ratio of (A= 12) tilted by angles of (15o
, 30o
, 45o
, 60o
, 75o
, and 90o
). A horizontal heated
cylinder with diameter of (16 cm) subjected under constant heat flux of (100, 500, 700, and
1000 W/m2
), the Rayleigh number ranging from (3.5 ×107
to 4.5 ×109
). At the bottom of the
rig left an opining with distance of (2, 4, 6, and 8 cm) but the upper left open to the
atmosphere. The tested cases was of (without fin, smooth, triangular, square, and semi-circle
fin) was attached to the right wall of the cavity. The numerical solution of the case was
performed by solving the governing equations by ANSYS-FLUENT 14.0 package that
dependent upon the finite volume method. The experimental results show that the Nusselt
number increases with increasing Rayleigh number, decreasing the inclination angle,
increasing heat flux and with increasing the bottom opining distance. Basically, the results
showed that the using fins with any geometry will lead to increase the heat transfer rate. The
optimum increasing in the Nusselt number was found by using triangular plat fin. Finally,
the experimental data was compared with a numerical calculation and found that there is a
good agreement in the same conditions

Welded parts are often subjected to variable loads. Paper’s aim is to evaluate the fatigue
characteristics of friction stir welding of AA6061-T6 alloy under variable loading and
observed the influence of heat treatment for friction stir welding joint on the fatigue stress
analysis. The microstructure of the welds alloy are studied before and after heat treatment.
The friction stir welding was employed using milling machine with constant tool rotation
(1000 rpm) and feed rate (20 mm/min). Artificial aging are made for aluminum friction stir
welded alloy using electrical furnace at temperature of 500ºC for 20 min. Quenching at
190ºC for 4 hr. via water is followed the aging process. Fatigue test were done for specimens
(base metal, friction stir welding alloys before and after heat treatment) to obtain the S-N
curves for each case. Finite element via ANSYS software is used to analysis the FSW
(temperature, Von-Mises stress, deformation in the welded zone and contact friction stress
distributions) and Fatigue test (fatigue life, fatigue damage, fatigue safety factor, biaxiality
indication , equivalent alternating stress and stress intensity factors) where the general
thermo-elasto plastic relation produced under thermal and mechanical loads with isotropic,
kinematic and mixed hardening rule in three dimensional problems is proposed. The results
shown that the heat treatment for the friction stir welded alloy would be increased the
fatigue strength of the welded plate that the number of cycles of base metal (AA6061-T6)
was 1.2×106
and the number of cycle for welded joints without heat treatment was
(0.9×106
), where the number of cycles was 1×107 with heat treatment with quenching within
4hr. also it can be concluded that, the fracture opening mode (mode I) is exist in the un
heated welded alloy and disappeared with heating treatment

In Iraq, the significant increase in the number of passenger cars and trucks (increased in
axle loads) in addition to the unprecedented rise of temperature in the summer has
increased the risk of permanent deformation of flexible pavement (Rutting) in recent
times. Lower costs maintenance and extending serves life of flexible pavements are the
main objectives of this study by improving rut resisting of it using the waste locally
available materials (Dates Kernel Powder).
The Superpave design criteria is used to determine optimum asphalt content at 4% air
voids for hot mix with Lime Stone Dust and Dates Kernel Powder as a filler materials to
three types of aggregate blend. Preparing 54 samples with dimension (400*300*50) mm
at 110˚C compacted temperature to test it by Wheel-Tracking device at 40˚C, 50˚C and
60˚C. Based on wheel-tracking device results, it can be show that there was a significant
decrease in the value of the Rut Depth when using the Dates Kernel Powder as an
alternative to Lime Stone Dust as a filler materials in Hot Mix Asphalt and it can be used
to improve the rut resisting; the maximum percent of reduction is 67.71 after 3000 cycle
of passing at 60ºC and 49.35 as a minimum percent of reduction after 5000 cycle at 40ºC
tested temperature, then it can be seen that the impact of Hot Mix Asphalt with Dates
Kernel Powder is less at high temperatures than mixes with Lime Stone Dust on Rut

In this work, aluminum metal matrix composites (AMMCs) were fabricated by using
powder metallurgy. AA7075 powder is reinforced with two different ceramic particles
(TiC,B4C) with different weight fractions (2.5, 5, 7.5 and 10 wt.%). The composites were
produced by powder metallurgy by preparing the powder, mixing, compacting and
sintering. The particle size of unreinforced AA7075 about 100µm, while particle size of
each TiC and B4C about 150 µm. The mixing process was done by planetary mixing setup
rotating at 250 rpm for 2hr. by adding zinc stearate as an activator material with steel ball
milling. However the mixture was compacted by hydraulic uniaxial press type (Leybold
Harris No.36110) about 200 kg/cm² according to (ASTM-D 618). After compacting
process, the mixture sintered at 475 °C for 2hr. by using electrical furnace with argon
atmosphere.
There are many examinations and tests were carried out for the synthesized composites
material (AA7075/ TiC and AA7075/ B4C) such as examination of the microstructure,
mechanical tests such as hardness and compressive strength, physical tests such as
density and porosity.
The results of this work showed that improving in physical properties (theoretical
density, experimental density, porosity) and mechanical properties (Rockwell hardness
and Compressive strength)

Minimizing the scheduling production time consider one of the most important factors for
companies which their objectives is achieve the maximum profits. This paper studies the
identical parallel machine scheduling problem which involves the assignment numbers of
job (N) to set of identical parallel machine (M) in order to minimize the makespan
(maximum completion time of all job). There are numerous troubles in solving the large
size of “parallel machine scheduling” problem with an excessive jobs and machines, so
the genetic algorithm was proposed in this paper which is consider an efficient algorithm
that fits larger size of identical “parallel machine scheduling” for minimizing the
makespan. Most studies in the scheduling field suppose setup time is insignificant or
included in the processing time, in this paper both the sequence independent setup times
and processing time were considered. The solutions of algorithms are coding in
(MATLAB). A numerical example of (11) jobs are schedule on (3) machines to
demonstrative the effectiveness of algorithm solution. The result show the algorithm can
effectively solve large size of scheduling problem and given the best schedule with
minimum makespan

The effect of DC pulsed GTAW method factors on mechanical properties of Aluminum
alloys 6061–T6 is proves. Throbbed GTAW on the sheet having dimension of (200* 100*
5mm) is implemented at variable pulse current (150, 160, 170, 190) and constant frequency
to get numerous connected joints by electrode type" ER4043 (Al Si5) as a padding metallic
and argon as protective gas and compared with base current GTAW welding at D C current
at 90 amps. The welded pieces are examined by X-ray radiography. The welded joints were
treated by heat, the joints heated for half an hour in the furnace to 150 C° then cooled in the
air to release the residual stresses. Mechanical quality of the weld joints. Microstructural
categorizations, Micro hardness, enduring stress are examined. Consequences exposed that
a common decline of mechanical properties of TIG welded joints conveyed 34% analogies
with parent metal while the PGTAW joined offers better mechanical qualities analogy with
of TIG joined in reductions conveyed 8.4% analogies with original metal this is because of
the microstructure variations through the joining method and compressive residual stress
generation in the weld zones. It has been found that by PGTAW improved the mechanical
properties of welded joints which rely on current parameters.

In this study, nano-composite of polymeric materials, prepared from unsaturated polyester
resin (UP). Two groups of nanocomposites were prepared by Hand Lay-up method. The first
group consists from (UP) reinforced by hybrid nanoparticles consisting of a mixture of
zirconium oxide and yttrium oxide (30 mol%Y2O3- ZrO2) with particles size (83.98nm). The
second group consists of (UP) reinforced by zirconia nanoparticles (ZrO2) with particle size
(47.23nm). The effect of volume fraction (0.5%, 1%, 1.5%, 2%, 2.5%, 3%) of the
nanoparticles additives on some mechanical properties of composites materials was studied
also. The results shown that the values of the flexural modulus, impact strength and fracture
toughness increased, as the volume fraction ratio of the nanoparticle increased for both
groups of nanocomposites, while flexural strength values decreased with the increased the
volume fraction ratio of the nanoparticles for both groups of nanocomposites also. As well
as, the unsaturated polyester resins reinforced by hybrid nanoparticles has higher mechanical
properties as compared with their counterparts of composites reinforced by zirconia
nanoparticles only. The morphological formation of the fracture surface showed a close
interconnection between all components of the prepared polymeric compositions. This
reinforce a good compatibility between unsaturated polyester resins and reinforcement
nanoparticles, which enhancement the mechanical properties.

Improvement of Wear adhesive properties using laser peening treatment at varied number of
pulse of Austenitic stainless 316L is studied. According to typical ASTM G99-05 number of
wear inspection test are prepared in dimensions 20x10 mm then compiled into four groups.
The surface test of three groups is exposed to a number of laser pulse 1, 2, 4 pulses
respectively by laser peening without coating. Microstructure, residual stress, hardness, is
tested. Wear test using pin on disc method are used on all groups of specimens at two
parameters, diverse times 10 ,20,30 min with constant load 1kg , and divers load 1,1.5, 2
kg with constant time 10 min. from results it was concluded that decrease in hardness and
rises in ductility shared to increases in wear properties for the original metal and leaser
peening participated to rise in the wear resistance due to increase in hardness , compression
residual stress and the heterogeneity of the evidence in the microstructure ,four pulse laser
peening give the lowest wear rate comparing with one pulse which witness decreases in
wear rate

This work represents an attempt to introduce further improvement on the
properties of these coatings, although the (Zn-Ni) 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 (Zn-Ni) and (Zn-Ni-SiC) particles with
different particles size of silicon carbide once microscale (73µm) and another nanoscale
(70-100nm) .After electroplating, these samples were analyzed by X-ray fluorescent to
confirm all the content for each alloy