Mathematical Model of Autoclave Curing of Epoxy Resin Based Composite Materials
A. Abdul
dnan
author
J.
Najat
author
Sh.
Hassen
author
text
article
2007
eng
Polymer matrix composites using thermosetting resins as the matrix are increasingly finding use in several applications. Process modeling describing the governing curing has played an important role, in improving the fundamental understanding and development of composite fabrication techniques. In present work, the thermokinetic involved in the autoclave curing of fiber-reinforced epoxy has been studied by means of a computer program, using the transient heat conduction equation coupled with kinetic equation, and the initial and boundary conditions. In the analysis the cure assembly is assumed to consist of a tool plate, composite laminate. The temperature distribution and the degree of reaction are obtained as a function of position and time.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
828
835
https://etj.uotechnology.edu.iq/article_181277_9957cf776630377f8fca403661ae5c8b.pdf
dx.doi.org/10.30684/etj.25.7.2
Improvement of Thermal Properties for Binary Systems PVFPh, PVF-B by Addition of Silicon Carbide
A.
Mohammed
author
text
article
2007
eng
Two binary systems of (PVF-Ph and PVF-B) were prepared at specificconditions, and then thermal properties were improved by addition of a ceramicmaterial (SiC).A different mixing ratio of ceramic material (SiC) powder was added to aprepared binaries (PVF-Ph, PVF-B) at (polyvinyl formal-phenol, and polyvinylformal-bitumen) with a range (0.1-1)gm varied with (1-0.1)gm addition from bothphenol (Ph) and bitumen ( B ).The thermal properties (thermal conductivity, stability) were measured forboth improved binary systems (PVF-Ph, and PVF-B), and the results proved that:All thermal properties of two binaries (PVF-Ph, PVF-B) are modified withexcellent properties of bitumen that will be raised from(50˚C to 250˚C) and othersystem (PVF-Ph) improved from (120˚C to 200˚C). Also the thermal conductivityis modified at a wide range from (0.0999 w/m˚C to 0.000477 w/m˚C.).A home made thermogravimetric system was designed to give TG-analysiscurve and check the stability of composite prepared system, where the resultsproved that the optimum mixing ratio of composite system gives high stabilityfrom (100˚C to 315˚C) with excess of ( 215˚C) than base one (PVF-B).
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
836
848
https://etj.uotechnology.edu.iq/article_181278_4e3b56a08ccfd2719dec702ecc7f5620.pdf
dx.doi.org/10.30684/etj.25.7.3
Effect of Zn% and Thermomechanical Treatments on the Mechanical Properties of Al-Zn-Mg Alloys
H.
Ali
author
text
article
2007
eng
The aging kinetics and the coupling between plastic deformation andsubsequent aging on a set of Al-Zn-Mg alloys having different Zn-content(6.33%, 7%, 7.5% and 8%) are investigated. These alloys are produced withan extreme care during melting, alloying and sampling where the bestconditions of alloying are adopted .The response to multi thermomechanicaltreatments practices are reported, where the combination between rollingpractice and aging is monitored by hardness measurements, tensile, impacttoughness measurements in addition to x-ray diffraction testing. The studyproves that, the zinc percent has a very important role in the precipitationhardening sequence of tested alloy; this effect is concentrated on the speedingup the kinetics of hardening by increasing the density and stability of GPzones and μ'-phase.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
849
862
https://etj.uotechnology.edu.iq/article_181279_894198b580859b9718ce8620d6f34017.pdf
dx.doi.org/10.30684/etj.25.7.4
Computer Aided Design and Modeling of FCCU Processing Iraqi Feed Stock
K.
Neran
author
H.
Shayma
author
text
article
2007
eng
The relationships between the process variables for a Fluid Catalytic Cracking unit (FCCU), processing vacuum gas oil (VGO) feedstock from Kirkuk crude oil, were studied depending on material and energy balance calculations. Computer programs written in Visual Basic (6.0) are developed to evaluate all the process variables. The steady state models is used to design the reactor, regenerator, fractionator and slurry settler. A hydrodynamic model for the complete description of the FCCU is developed. The model simulates the riser and the regenerator and incorporates operating conditions, feed properties and catalyst effects. The effect of the selection of the input (manipulated variables) on the output (measured variables) for the reactor and regenerator is also studied.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
863
878
https://etj.uotechnology.edu.iq/article_181280_56ab0c4bef8d74e06a3d3a4ff52ce421.pdf
dx.doi.org/10.30684/etj.25.7.5
The Effect of Cutting Tool Vibration on Surface Roughness of Workpiece in Dry Turning Operation
Y.
afeen
author
K.
Younis
author
text
article
2007
eng
his study is to find a correlation between surface roughness and cutting tool vibration in turning. The ranges of process cutting parameters in the present study are limited: cutting speed (34, 70, 130 m/min), depth of cut (0.1, 0.2mm), feed rate (0.07, 0.13, 0.17mm/rev) and tool overhanging (25, 30, 35, 40mm). The data are generated by lathe dry turning of medium carbon steel samples at different levels of the mentioned above parameters. Dry cutting tests (without using cutting fluid) are conducted to simulate a good turning, the dry turning provided a clean environment to obtain undisturbed clear cutting vibration, which results in more accurate and clear correlation between cutting vibrations and roughness. The analysis of variance reveale in this study is that the best surface roughness condition is achieved at a low (feed rate less and equal 0.13mm/rev), and with smaller tool overhang less and equal 30mm). The results also show that the cutting speed has small effect on surface roughness than feed rate and tool overhang. The depth of cut has not a significant effect on surface roughness in this study. Above results can be obtained when there is no built up edge and no damage of the tool tip. Finally experimental results have shown good correlation between the cutting tool vibration and surface roughness which can be used to control the finish surface of the workpieces during the mass production.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
879
889
https://etj.uotechnology.edu.iq/article_181281_7c396e9c4d17c67f3c15b984381da5d9.pdf
dx.doi.org/10.30684/etj.25.7.6
Gain Characteristics of Silicon Transistor Treated by Laser
O.
Rana
author
text
article
2007
eng
In this work, profiles of laser-induced diffusion of arsenic in silicon arepresented. These profiles are considered to attempt increasing of the currentgain of silicon transistors. The current gain is well enhanced. Thisenhancement is attributed to the increase achieved in the diffusion lengthwithin a certain layer of emitter region. Laser-induced diffusion is a perfecttechnique for improving the characteristics of electronic devices since it isflexible, contactless, clean and well controlled.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
890
896
https://etj.uotechnology.edu.iq/article_181282_61ee522a79882206cae766522e1e0620.pdf
dx.doi.org/10.30684/etj.25.7.7
Cumulative Damage in Fatigue of a Structure Subjected to Random Loading
Karim
Kadhim
author
text
article
2007
eng
When a structure is subjected to a random loading, its dynamic response changes, characterized by shifts in the eigenvalues and modification of eigenvectors. The peaks in the dynamic response spectrum will give indications of the natural frequencies of the structure. Any damage in the structure will be reflected in the spectrum as a shift in natural frequencies. Crack initiation and early growth of fatigue cracks in 0.4% carbon steel and 2024-T4 aluminum are investigated using spectral density approach for applied random loading. Energetic consideration and spectral density approach lead to the formulation of a model used to predict the behavior of short and long cracks initiation, propagation, and paths taking into account the microstructural variables relevant to fatigue crack initiation and early crack growth. The model indicates that crack arrest occurs when crack-tip is blocked by a grain boundary. In the short crack region, propagation and non-propagation occurs depending on random loading stress level and slip band energy released. The application of the present model to cumulative damage is compared with the experimental data and a reasonable agreement is found. The introduction of material specification shows a quantitative description of the parameters which affect the reliability of a structural component subjected to random loading. The power of the analytic model and the simulation analysis in the present work give some insight to the behavior of the structure under random loading showing the different mode shapes, eigenvalues/vectors, deformation, propagation and non-propagation of cracks, and the stresses caused by such random loading that can lead to fatigue failure. A life predication model is presented for long-life fatigue , to control the hardware design and to find a proper combination of random load and life .
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
897
917
https://etj.uotechnology.edu.iq/article_181283_73f59bdadd4341c5533eeb09b2d0d27e.pdf
dx.doi.org/10.30684/etj.25.7.8
Improving Oxidation Resistance of Stainless Steel (AISI 316L) by Pack Cementation
Ali
Ahmad
author
Khedeir
Muna
author
Mohammed
Rajab
author
text
article
2007
eng
The cyclic oxidation resistance of austenitic stainless steel (AISI 316L) can be improved by enriching the surface composition in Al and Si using pack cementation process. In this work, stainless steel is coated with two different types of coatings, the first one is Si-modified aluminide coating and the second is the Ce-doped silicon modified aluminide coating. Aluminum, silicon with and without cerium were simultaneously deposited by diffusion into St.St.316L substrate by the pack-cementation process, using a pack mixture containing (18%A1, 7%Si, 2%NH4C1 and 73%Al2O3) and 0.5% Ce (wt %) when required. Microstructure and chemical composition of the coated specimens were analyzed using electron microscopy (SEM) with energy dispersive spectroscopy (EDS). X-Ray diffraction (XRD) was used to identify phase formed in the surface layer of as-coated specimens. The coating time was changed, and it was found that diffusion coating time of 3h at 970C° produces coating thickness of 160-180μm and consist mainly of FeAl and (Cr4Si4Al13) phases. Also, the surface morphology for the coated samples after 3h coating time at 970C° are dense, smooth and homogeneous. Cyclic oxidation tests were conducted on the uncoated St.St.316L , Si-modified aluminide coating and on Ce-doped silicon modified aluminide coating at a temperature range between (700-900)C° in (air and H2O) for 120h at 10 h cycle. The oxidation kinetics for uncoated St.St.316L in air environment are found to be linear, while the oxidation kinetics at water vapor environment are found to be nearly parabolic. The linear rate constant (KL) and the parabolic rate constant (Kp) values obtained at 800C° in air and water vapor are –2.77*10-7(mg/cm2)/s and 2.18*10-5(mg2/cm4)/s respectively. The phases present on the cyclic oxidation of uncoated St.St.316L surface under most test conditions as revealed by XRD analysis are chromium (III) oxide, NiFe2O4, NiCr2O4 and iron oxide. Oxide phases that were formed on coated systems during air and H2O oxidation exposure condition are FeAl2O4, Fe(Al,Cr)2O4 and Fe2O3. The oxidation kinetics for both coated systems in air and water vapor are found to be linear and parabolic respectively.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
918
939
https://etj.uotechnology.edu.iq/article_181284_14b78c7b3b57f702572693d8255518a4.pdf
dx.doi.org/10.30684/etj.25.7.9
Effect of Window Over-Hang in Iraqi Building on Cooling Load
Farag
Nazar
author
text
article
2007
eng
A study is done on an Iraqi building to estimate and show how the use ofover hang reduces the cooling load. The study shows how the effectiveness ofover hang is affected by the orientation and the area (height) of the windows.This study shows that limit width of over hang on south window reduces thecooling load by (9%), and when using the over hang on the east or westwindow we need a large width over hang to reduce the cooling load by thesame percentage. Also this study shows that using over hang and increasingthe area of south windows allow us to receive a wide range of solar radiationin winter and use it in heating and lighting and the cooling load does notincrease by the same percentage when using west or east windows. The resultsshow that the using of over hang in Iraq is important especially for southwindows.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2007
940
949
https://etj.uotechnology.edu.iq/article_181285_51c8657eb6431ad59575f160498caef4.pdf
dx.doi.org/10.30684/etj.25.7.10
دراسة خواص الزحف للمواد المتراكبھ ذات أساس (Al-Mg-Si) مقواة بدقائق من كربید السلیكون
text
article
2006
eng
The aim of this work is to study the deformation behavior of (Al-Mg-Si) alloy reinforced with silicon carbide at elevated temperature under creep. In this research both matrix-alloy and composite material were prepared using stir-cast technique. The cast specimens were deformed using rolling process and then heat treatment was done for both matrix alloy and composite material Creep test were done at (١١٠،٢٤٠،٣٢٠) ºC used stresses (٩,٧, ١٩,٤) MPa for master alloy and stresses (٣٨,٤, ٥٧,٧) MPa for composite material. The composite material reveals lower steady state creep rate than matrix alloy especial at low temperature so it is possible to conclude that composite material has better creep resistance than matrix alloy. Scanning electron microscope result of fracture section showed that void are formed near silicon carbide and near second phase which indicates that the failure in composite material began by forming voids which connect together to form cracks which expended leading to failure.
Engineering and Technology Journal
University of Technology-Iraq
1681-6900
25
v.
7
no.
2006
https://etj.uotechnology.edu.iq/article_181276_f7eef8e0f267879cd396017577240617.pdf
dx.doi.org/10.30684/etj.25.7.1