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Iraqi journal of mechanical and material engineering

المجلة العراقية للهندسة الميكانيكية وهندسة المواد

ISSN: 20761819
Publisher: Babylon University
Faculty: Engineering
Language: Arabic and English

This journal is Open Access

About

Iraqi journal for mechanical and material engineering is a refereed scientific journal published quarterly by the engineering college/ university of Babylon. It deals with high quality researches in fields of mechanical and material engineering.

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Contact info

Journal E-mail:
j.mec_mat_eng@yahoo.com
Babylon university/Babylon/Iraq P.O.Box(4)
Tel:++96430245387.(1155)

Table of content: 2009 volume:9 issue:1

Article
PREDICTION OF SHOCK WAVE AND EXTERNAL FLOW FIELD PARAMETERS IN A MODERATE SUPERSONIC FLOW OVER A 3-D ARC CIRCULAR BUMP

Authors: Dr. Ahmed Kadhim Hussein
Pages: 1-14
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Abstract

This study is used to compute the primitive variables of moderate supersonic flow based on finite difference computational fluid dynamic methods. The problem considered deals with a three-dimensional external, inviscid ,compressible supersonic flow over a three-dimensional arc circular bump. In this work, Euler equation was solved using time-marching MacCormack’s explicit technique. The flow conditions are taken at sea level and Mach number at 1.97. To deal with complex shape of arc circular bump the so-called “body fitted coordinate system” were considered and the algebraic methods were used to generate grids over an arc circular bump. The results showed a good agreement with other published results.


Article
DYNAMIC BEHAVIOR OF GAS-SOLID FLOW IN HORIZONTAL PIPES

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Abstract

The dynamic behavior of a two phase (gas-solid) flow in a horizontal pipe is studied in this work. The experimental and theoretical methods are set to examine the effects of inlet velocity, loading ratio for different sizes of solid particles on the pressure, velocity and the volume phase fraction along the pipe .The range of velocities used in this work are between (12-42 m/s) and the loading ratios are between (2-12) as mass of solid to mass of air. The solid is the sand at four groups of particle size (150-300 ), (300-425 ), (425-600 )and (600-850 ). The experimental rig is constructed to measure the inlet velocity and pressure along (3.175cm) diameter (6m) long horizontal pipe. The results show that the loading ratio (LR) and Reynolds number (Re) are the main parameters that control the pressure drop along the pipe. The pressure drop increases as both Reynolds number and loading ratio increase whereas the effect of particle size is opposite to that effect. The pressure drop for a small particle is less than for the larger one. The empirical correlation that relates the friction coefficient (Cf) through the pipe is represented by the dimensionless groups (Re), (volume fraction, ) and (Froude number, Fr). The theoretical analysis consists of the solution of the steady state and the unsteady state of the differential equations using the boundary conditions that govern the two phase (gas-solid) flow GSVF is the computer program that was build to simulate the dynamic behavior of the flow involved in the semi-empirical correlation for (gas–solid) interaction (Sa). The dimensionless number (SR) suggested in this work indicates that the volume fraction is the most effective parameter than Re and Fr. The volume fraction, velocity and pressure profiles are evaluated as the output of the computer program, only the pressure profiles are compared with the experimental values. The pressure drop and the friction coefficients produced from the theoretical analysis show that the theoretical values are (24%) higher than the experimental one.

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Article
THE SLUMP PROBLEM OF CELLULAR CONCRETE BLOCK (THERMOSTONE)

Authors: Montadher A. Muhammed
Pages: 41-52
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Abstract

The research treats the problem of slump(as a type of creep) under self weight, that thermostone suffers during manufacturing process because the large dimensions and viscoelastic properties that the material has. Chemical composition and the percentage of added elements, especially the Gypsum and their effect on slump problem are studied using a practical method. The viscoelastic solution is applied here by Finite Element Method using the suitable model and taking with care the phenomena of aging. The viscoelastic solution is compared with the practical results for several stages of adding Gypsum.


Article
EFFECT OF THERMOMECHANICAL TREATMENTS ON AGING BEHAVIOR AND FRACTURE TOUGHNESS OF AL-CU-MG ALLOY PLATES USED IN AIRCRAFT STRUCTURE

Authors: Dr. Alaa A. Ateia,
Pages: 53-67
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Abstract

The effects of variations in the thermomechanical treatments parameters on the microstructure and mechanical properties of Al-Cu-Mg alloy plates used in aircraft structure subjected to a post heat treatments have been conducted. It was confirmed that a large gain in fracture toughness combined with a good mechanical properties could be achieved by choice of the correct initial condition, amount and temperature of deformation, and the time temperature of the final age hardening sequence. In general, it was found that the material should be age hardened to the peak hardness conditions before deformation at an elevated temperature (warm rolling at 200°C) in order to prompt homogeneous slip. Room temperature deformation resulted in planar slip at the peak hardness conditions non uniform response on subsequent aging and give lower fracture toughness.


Article
FORMATION OF NI-SB PHASES BY ELECTRO-CODEPOSITION DIFFUSION COATING
تكوين أطوار Ni-Sb بطريقة الترسيب الكهربائي _ الانتشاري للطلاء

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Abstract

Electrodeposited metal matrix/metal particle composite coatings (EMMC’s) were deposited, heat treated and characterized. Nickel matrix/ antimony particulate coatings deposited on Inconel 600 substrate (Ni-base superalloy) was chosen as a model system. The microstructure of the plated and heat treated coatings was characterized using light optical microscope (LOM) and X-ray diffraction analysis (XRD). Results showed that Ni5Sb2, Ni3Sb, and NiSb phases are presented in the coated layer. Further NiSb is a good source for Sb2O4 compound formation under open heating. This oxide has good stability at high temperatures.


Article
AN INVESTIGATION TO THE COMBINED EFFECT OF NON-UNIFORM PERMEABILITY AND SHAFT MISALIGNMENT ON THE PERFORMANCE OF POROUS BEARINGS

Authors: Lekaa' H. Abd Al-shaheed
Pages: 76-89
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Abstract

A porous bearing with misaligned journal and non uniform permeability has been investigated through the present work. The Reynolds' boundary condition has been used to determine the boundary of the effective oil film. Two types of misalignment, axial (vertical displacement) and twisting (horizontal displacement) with different values have been adopted. Two models are considered to analyze a finite porous bearing with misaligned shaft and non uniform permeability. In the first model the permeability a cross the radial direction has been varied, while in the other model the axial permeability has been varied. Effect of different supply pressure and misalignment are investigated for a particular bearing permeability. It was found that there is a slight effect to the supply pressure on the performance parameters of the porous bearing. Varying the permeability in radial and axial direction cause an increase of load carrying capacity with slight increase in coefficient of friction. It is also noticed that the journal misalignment has a considerable effect on the bearing performance.


Article
ESTIMATION OF FLEXURAL CREEP MODULUS OF SHORT FIBER REINFORCED POLYMERIC COMPOSITE MATERIALS USING (FEM)

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Abstract

The present work is a theoretical macro mechanics study, which concentrates on linear viscoelastic creep behavior of short fiber reinforced polymeric composite materials to estimate their flexural creep modulus at constant room temperature and at a time range of 1 to 10 9 seconds. The loading cases are concentrated and the deformations have been limited with small strains without permanent deformation. A three-parameter model is used as a mathematical viscoelastic model. A finite element program in Quick Basic had been designed to obtain the flexural creep modulus. Halpin-Tsai equation shows an improvement in the modulus values for composite materials reinforced with short fibers in both aligned and random reinforcement through flexural creep estimations. On the other hand, the modified rule of mixtures shows a slight effect of reinforcement on this property. 56789ا:


Article
Soft Soldering of Ferritic Nodular Cast Iron to Aluminum-Zinc Alloy
ربط حديد الزهر ذي الكرافيت الكروي الفرايتي بسبيكة الالمنيوم- خارصين

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Abstract

The research devoted the possibility of soft soldering ferritic nodular cast iron to aluminum - zinc alloy, by using filler metals ASTM 60A, 40A & 70A. Cast iron was electroplated with iron and tin, while aluminum was coated with different layers of zinc, zinc-copper, zinc-copper-tin, zinc-copper-nickel and zinc-copper-nickel-tin. The specimens were fixed in the overlap position, and heated in a furnace to temperatures suitable to the soldering alloy in different holding times 5, 10, 15, 20, 25, 30 & 40min. The bond on the aluminum side could not be achieved when it was immersion coating with zinc while electroplating aluminum with copper over the zinc gave shear strength of 7MPa at 30min. holding time, using 60A as soldering alloy. Electroplating another layer of tin on aluminum increased shear strength to 11MPa at the same holding time and soldering alloy. While electroplating with nickel layer on the aluminum after zinc and copper layers gave shear strength of 10MPa. Adding fourth layer of tin on aluminum helped increasing shear strength to 23MPa . Using 40A as a solder alloy with the same two plated layers on cast iron and the four layers on aluminum gave shear strength of 14MPa while 70A solder achieved 13MPa at holding time 25min. The microstructure examinations show the formation of intermetallic compounds on both metals while the X-ray diffraction test shows the formation of FeSn and FeSn2 phases on the cast iron, and ε-Cu3Sn, η-Cu6Sn5 and γ-NiSn, δ-Ni3Sn4 on the aluminum, which are responsible for the bond.


Article
PREPARATION OF INSULATOR MATERIAL AND STUDY ITS THERMAL AND MECHANICAL PROPERTIES
تحضير عازل حراري ودراسة خواصه الحرارية والميكانيكية

Authors: د. علي هوبي حليم
Pages: 119-124
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Abstract

Due to increasing the importance of search about materials which have the capability to resistance generated flame from fires and in the same time acts as an insulator material so, this research introduced a material combined between these characteristics. In the present research, the preparation method of an insulator material, which composed of phenol – formaldehyde reinforced by carbon fibers up to 40% weight percentages, was expressed, as well as described thermal and mechanical properties. Thermal erosion test was indicated the performance of the insulator material efficiency to thermal insulation and flame retardancy. Thermal Erosion rate is 0.166mm /Sec. Mechanical properties (compression test, impact test, flexural test) indicated high toughness of insulator material.

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