Table of content

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: 2011 volume:11 issue:2

Article
Numerical Study of the Unsteady State Cross Flow Heat Exchanger with Variable Fluid Parameters
نموذج رياضي لمبادّلِ حراري متقاطع الجريان غير مستقر مع مائع ذو خصائص متغيره

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Abstract

ABSTRACT A numerical model for the unsteady state cross flow heat exchanger with variable fluid parameters is presented. The model contains many sophisticated assumptions that always avoided in the traditional analyzing of cross flow heat exchanger like variation of fluid properties (density, viscosity, thermal conductivity and convection heat transfer coefficient) and three dimensions unsteady state. The hydrodynamic properties for both fluids are taken as fluid temperatures dependence. The heat transfer from the hot fluid to the surrounding cold fluids, and the heat exchanged between the cold fluid and the surrounding hot fluids channels and surrounding cold fluids ducts are taken in account. The air is used as cold fluid, while the water as hot fluid. A numerical analysis by using Finite difference method is used to solve the governing equations for both hot and cold fluids. The results shows that at small values of dimensionless X-xis (X = ΔX - 3ΔX) (ΔX = 0.021625), the hot fluid temperature decreases at a constant value of dimensionless Y-Axis (height). The hot and cold fluid temperature lines are curved and lower values of the temperature in the left side (X = ΔX - 3ΔX) and higher values of the temperature in the right side (X = 5ΔX - 8ΔX). The hot and cold overall effectiveness of the system increase with increase number of the cold duct per pass (ncp).


Article
TURBINE BLADE COOLING BY AIR USING DIFFERENT METHODS
تبريد ريشة توربين باستخدام طرق مختلفة

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Abstract

ABSTRACT The determination of temperature distribution within a turbine blade is important in regards to avoid excessive high metal temperatures and temperature gradients. The prediction of temperature distribution was achieved through the use of the finite difference technique, developed to solve the problem with the transformation and grid generation techniques. Steady-state two-dimensional conduction heat transfer equation was applied to the internal nodes in mesh to get the temperature distribution, where at the surface nodes (outer, inner), forced convection heat transfer equation was applied. The solution of the problem was established using computer program, which serves to solve the equations by using Gauss-Siedel iterative method. In the present study, three cases are used for thermal analyses of the blade, which requires the specification of external and internal boundary conditions. It is also found from the results obtained that the best cooling method to the turbine blade have been obtained for the third case when the blade cooled by impingement and film cooling method. It was found in the film cooled blade that the blade temperature decreases about (170 K) cooler than the blade cooled without the film cooling method. The results of thermal analyses obtained were compared with the finite element results. The comparison shows that the finite difference results give a good agreement with the finite element results with a small difference was calculated to be (3.5%) as maximum value and it fall to (0%) in most regions.


Article
STUDY OF MIXED CONVECTION IN A SQUARE ENCLOSURE WITH A ROTATING CIRCULAR CYLINDER AT DIFFERENT VERTICAL LOCATIONS
دراسة للحمل المختلط داخل حيز مربع بوجود اسطوانة دائرية دوارة في مواقع عمودية مختلفة

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Abstract

Abstract Mixed convection in a square enclosure with a rotating circular cylinder located at different vertical locations is numerically studied. The horizontal and vertical walls are kept at constant temperature Tc, while the surface of the rotating circular cylinder is maintained at a constant temperature Th. A two dimensional solution for steady laminar mixed convection is obtained by solving governing equations in stream function-vorticity form with finite difference technique for different Richardson number (Ri=Gr/Re2) varying over the range of 0.0 to 10. Depending on the Richardson number the convection phenomena inside the enclosure becomes natural, mixed, and forced convection. For the first time this study goes to investigate the effect of changing the rotating circular cylinder positions along the vertical centerline on the fluid flow and heat transfer inside the enclosure. The phenomena inside the enclosure is analyzed through a streamlines, isothermal patterns and average Nusselt numbers. The results show that the flow field and temperature distribution inside the enclosure are strongly dependent on the Richardson numbers and the position of the rotating circular cylinder, and the enclosure has maximum heat transfer rate when the cylinder near the bottom wall (δ=0.25).


Article
The Effect Of Sloping Angle And Orientation Of Inclination Roofs In Frame Building In Baghdad City On it's The Electrical Energy Consumption For Cooling Purpose
ةنيدم يف ةيلكيهلا ةينبلأل ةلئاملا فوقسلا هيجوتو تأثير زاوية ميل بغداد على الطاقة الكهربائية المستهلكة لأغراض التكييف فيها )ةيبيرجت ةسارد(

Authors: Atif Ali Hasan عاطف علي حسين
Pages: 262-278
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Abstract

Abstract :- The object of this paper is to find the relationship between slop angle, orientation for inclination roofs which used in frame building (steel & concrete) in Baghdad city. (Latitude 33.3º North), and it's effect on the solar heat gain value which transferred through that roofs and it's effect on the electrical power consumption for summer cooling purpose. The researcher is build (1 x 1 x 1)m frame building sample, it’s roof is rotated horizontally eight times and is made by two parts, first part is called frontal part (it’s slop angle would vary from 5° to 45°), the second part is called rear part (it’s slop angle would vary from 90° to 5°). Finally , the researcher was found the relationship between that angles will be taken the following form :  If frontal angle less than 20°, the minimum electrical energy was occur at North , North East and North-West, when rear angle is 20°, while , for East, West and East-South was occur at 10°, the another orientation at 5°.  If frontal angle equal to 20°, the minimum electrical energy for cooling was occur at 5° rear angle for all orientation.  If frontal angle more than 20°, the minimum electrical energy was occur for North & East North at 20° rear angle, while, for South orientation at 5°, while the other orientation was occur at 10° rear angle. And also, can notice that the roofs 20° frontal angle & 10° rear angle is consuming lowest energy for cooling with all orientation .


Article
EXPERIMENTAL METHOD FOR CALCULATION OF LAMINAR BURNING VELOCITY OF PARAFFIN GASEOUS FUEL IN CLOSED VESSEL USING DATA ACQUISITION SYSTEM
طريقة عملية لقياس سرعة الاحتراق الطباقية لوقود غازي بارافيني في وعاء مغلق باستخدام نظام اكتساب البيانات

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Abstract

ABSTRACT The burning velocity is defined as the velocity at which unburned gases move through the combustion wave in the direction normal to wave surface. It is used in many areas of combustion science such as in designing burners and predicting explosions. In this research a data acquisition system has been designed to measure the laminar burning velocity using a modern technique, which uses thermocouples as measuring sensors connected to a an interface computer. The hardware has been designed to connect three groups of sensors to the computer. A program has been used to access the interface and to acquire the huge measured data which is filtered through reading in a suitable manner. The results made it possible to achieve an imperical equation can be used in evaluating laminar burning velocity of parraffin gaseous fuels, the expermintal investigations show acceptable computations compared with previous researches results.


Article
MODELING THE SURFACE CHARACTERISTICS OF SHOT PEENED 2024 ALUMINUM ALLOY
نمذجة المواصفات السطحية لسبيكة الالمنيوم 2024 المسفعة بالكرات

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Abstract

Abstract The present research aims to study the effect of shot peening time (SPT) using metal balls (stainless steel balls) on surface roughness ,hardness and residual stresses .the above first two parameters (roughness, hardness) were measured before and after shot peening،While the third parameter i.e. the residual stresses were calculated based on the original yield stress of the ALUMINUM ALLOY 2024. The above three parameters were empirically modeling using the curve fitting equations The following conclusions can be drawn from this work: 1- Surface roughness increases with increasing the (SPT). 2- The hardness increases with increasing SPT (For the current study an improvement of 36.75%) using shot peening of 2024-Al alloy. 3- The compressive residual stresses increases with increasing SPT (for the present study an improvement of 11%using shot peening of 2024 –Al alloy.


Article
DESIGN AND ANALYSIS OF A NEW PROSTHETIC FOOT FOR PEOPLE OF SPECIAL NEEDS
تصميم وتحليل قدم صناعي غير مفصلي لذوي الاحتياجات الخاصة

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Abstract

ABSTRACT: Loss of the lower limb can cause loss of mobility .At all places and at all times, efforts have always been made to make up for such a loss. The basis of this investigation is to research current prosthetic in order to design and build a more human like prosthesis. Also this investigation aims at combining these characteristics in order to achieve a more multi functional prosthesis. In undertaking such a design, the new prosthesis will be exhibit a broader range of characteristics than those displayed in current prosthetic feet. In doing so, the new prosthesis will enable a closer representation of the functions inherent of a normal human foot. The characteristics involved in normal walking include dorsiflexion, impact absorption and fatigue foot test. The characteristics displayed in the manufactured new foot tested were compared to those of SACH foot. The characteristics exhibited by prostheses which compared favorably to those of a human foot were investigated further. A new prosthetic foot is designed and manufactured from polyethylene and a comparison study with SACH foot was used to determine if there are differences in the gait pattern while wearing the NEW foot and whether these differences would be problematic. The basis of the new prosthetic design combines current prosthetic design elements, such as materials and components. The analytical part presents the results of the static and fatigue analysis by methods; numerical methods (Finite Element method FEM) and experimental methods. The new foot was designed and the number of cycle, dorsiflexion and impact were measured. The new prosthetic foot has a good characteristic when compared with the SACH foot, such as good dorsiflexion (7.8-6.4o), force transmitted at impact heel (9.82N-9.50N) and life of foot (2,103,445-896,213) cycles respectively.


Article
DYNAMIC RESPONSE ANALYSIS OF VISCOELASTIC MOVING BELTS
تحليل الاستجابة الديناميكية للأحزمة الناقلة للحركة المصنوعة من مواد لزجة مرنة

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Abstract

Abstract The dynamic response and stability of parametrically excited viscoelastic belts are investigated in the current study. In this work, the generalized equation of motion is obtained for a viscoelastic moving belt with geometric nonlinearity. Non-dimensional analysis of the model was built on some assumptions to simplify the problem. The viscoelasticity of the model was modelled using Kelvin-Voigt model, the dynamic equation of motion derived using perturbation technique. The displacement of vibration found using the zeroth order solution that was subdivided into two parts, real and imaginary parts, due to the nature of nonlinear system. In this research effects of many elastic and viscoelastic parameters are studied, it was shown that there exists an upper boundary for the existence condition of the summation parametric resonance due to the existence of viscoelasticity. Effects of viscoelastic parameters, excitation frequencies, excitation amplitudes, and the axial moving speed on dynamic responses and existence boundaries were investigated.


Article
THE EFFECT OF HEAT TREATMENT TEMPERATURES (ANNEALING, AGING AND DOUBLE AGING) ON HARDNESS OF 16%NI CAST MARAGING STEELS
دراسة تاثير تغير درجات الحرارة للمعاملة الحرارية (التلدين -التعتيق) على صلادة الفولاذ المراجيني الحاوي على نيكل بنسبة16%

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Abstract

Abstract The primary purpose of the present work was to study the effect of different annealing and aging temperature on the mechanical properties of 16%Ni cast Maraging steels. In addition subsidiary studies were made of the hardening mechanism responsible for high strength. It was found the annealing temperature must be done above approximate 750C◦ but not exceed 1250C◦ to give the good hardness during aging.. Marked hardening occurred within several minutes during from 485oC to545 oC but only after several hours in the range between 325 to 375 oC Heat treatment of 3 hour at 485 oC of cast alloys was most satisfactory. While the aging at 485 oC for long time decrease this hardening caused softening due to the reversion of the body centered cubic matrix to austenite. The aging kinetics mechanism refer to that lattice defect were influencing the reaction rate. X-ray diffraction evident indicated the formation of any bcc structure of matrix as martensite and the appeared that hardness was due to coherent precipitate having concentration in matrix that formed as Fe2CoNi,Ni3Ti and Ni3Mo phases. The double aging of cast alloys in different temperature given normal hardening result.


Article
EFFECT OF FIBER ORIENTATION ON FATIGUE OF GLASS-FIBER REINFORCEMENT EPOXY COMPOSITE MATERIAL
دراسة تاثير اتجاه الالياف على الكلال للمادة المتراكبة ذات اساس الايبوكسي المدعم بالياف الزجاج

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ABSTRACT In this research, the main objectives of this investigation as, first, study the effect of fibers orientation on fatigue strength for composite materials, second, study the effect of fiber orientation on shape and direction of fracture surface for composite materials. The experimental work using to study fatigue limit for composite material with different fiber orientation as (00, 30o, 450, 60o, 90o) and study of the fatigue surface (shape and direction of fatigue surface of composite material) for each fiber orientation fiber. The material using for composite material in this research are epoxy resin matrix and glass reinforcement fiber with volume fracture of fiber in composite material about (0.21). The results are endurance fatigue strength with number of cycle for fiber orientation (00, 30o, 450, 60o, 90o) and the shape and direction of surface fatigue of composite material.


Article
REDUCING KAOLIN SHRINKAGE BY USING KAOLIN GROG
تقليل تقلص الكاؤلين باستخدام الكاؤلين كورك

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Abstract

ABSTRACT In this work, the suitability of using local Kaolin and Kaolin Grog to reduce shrinkage in clay product like firebrick was experimentally investigated and the optimal ratio of Kaolin grog constituent determined. Ten samples of different compositions were fired at a temperature of 1200ºC. Three of the samples (samples 8, 9, and 10) crumbled during firing. The surviving samples gave the following limits of results:- Total shrinkage: 28%- 9.8%; apparent porosity: 63.6% - 77.13%; water absorption: 47.83% - 60.2%; bulk density: 1.329g/cm3 - 1.281g/cm3; apparent density: 5.60g/cm3 – 3.65g/cm3; and compressive strength: 61.5MPa – 52.11MPa. The results showed that the first seven samples had good shrinkage and compressive strength. Mixing ratio of 35:100 (representing weight in grams of water and Kaolin respectively) which represent the critical water content.


Article
STUDY OF THE EFFECT OF ACETONE DILUTION PERCENTAGE ON MECHANICAL PROPERTIES OF EPOXY-ACETONE SYSTEM
دراسة تأثير النسبة المئوية للألأسيتون على بعض الخواص الميكانيكية لمادة ايبوكسي - أسيتون

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Abstract: A series of epoxy-acetone blends have been prepared with different acetone percentages. After stiffening, the prepared epoxy samples are cured in 40°C for 24 hrs. Then a tensile test for the material specimens was performed by a universal computer aided testing machine. The measured tensile tests for the specimens reveal that as the acetone percentage is increased, the elastic properties are increased. Nevertheless, when the acetone percentage reaches a maximum value, the tensile properties decreases with further increase in acetone percentages. The results are explained in terms of that the acetone additions reduces the cross linking density and reduce the brittle character of the prepared epoxy. When the acetone content is more than (5%), the strength becomes to decrease due to severe reduction of cross linking density


Article
"STUDYING THE EFFECT OF NITRIC ACID ON REINFORCED AND UNREINFORCED UNSATURATED POLYESTER "
"دراسة تاثير حامض النتريك على البوليستر غير المشبع المقوى وغير المقوى

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Abstract:- The aim of this work is to study the effect of different concentrations of nitric acid (20%,40%,60)for each 100ml of distilled water on unsaturated polyester and composite material. The composite material consists of unsaturated polyester reinforced with powder of aluminum at (0.1, 0.25, 0.5)wt% for (2-10) days. Nitric acid affects on unsaturated polyester through: physical degradation which represents by yellowish of polymer, swelling, the formation of pits, and hydrolytic corrosion. The presence of aluminum powder will inhibit the molecules of solution from penetration into the cross-linked polymeric chains and consequently will decrease the swelling at 0.1 wt% but the reinforcement with greater ratios of aluminum powder will lead to increase in weight.

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