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Temperature and Stress Evaluation during Three Different Phases of Friction Stir Welding of AA 7075-T651 Alloy
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The current study performs an explicit nonlinear finite element simulation to predict temperature distribution and consequent stresses during the friction stir welding (FSW) of AA 7075-T651 alloy. The ABAQUS® finite element software was used to model and analyze the process steps that involve plunging, dwelling, and traverse stages. Techniques such as Arbitrary Lagrangian–Eulerian (ALE) formulation, adaptive meshing, and computational feature of mass scaling were utilized to simulate sequence events during the friction stir welding process. The contact between the welding tool and workpiece was modelled through applying Coulomb’s friction model with a nonlinear friction coefficient value. Also, the model considered the effect of nonlinear material properties as well as heat transfer conditions such as heat losses due to convection and thermal contact conductance between the workpiece and the backing plate interface on the thermal history. To validate the computational model results, an experimental procedure was carried out to measure temperature history on both sides of the specimen as well as the plunging force throughout the whole process time. The results obtained showed that symmetrical temperature distribution throughout the workpiece width was distinguished, implying that the tool rotation has a minor effect on the final temperature distribution. In addition, asymptotic V shape with high gradient temperature value in the weld nugget region after the full plunging was distinguished. Mechanical stresses and related plastic deformations generated, while achieving the FSW samples were evaluated in addition to the tool reaction force and heat generated to protect against tool failure.

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Publication Date
Fri Jan 29 2021
Journal Name
International Journal Of Applied Mechanics And Engineering
Unified Methodology for Strength and Stress Analysis of Structural Concrete Members
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Abstract<p>In this paper, a methodology is presented for determining the stress and strain in structural concrete sections, also, for estimating the ultimate combination of axial forces and bending moments that produce failure. The structural concrete member may have a cross-section with an arbitrary configuration, the concrete region may consist of a set of subregions having different characteristics (i.e., different grades of concretes, or initially identical, but working with different stress-strain diagrams due to the effect of indirect reinforcement or the effect of confinement, etc.). This methodology is considering the tensile strain softening and tension stiffening of concrete in additio</p> ... Show More
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Publication Date
Tue Oct 01 2019
Journal Name
Journal Of Engineering
Generation and Experimental Stress Analysis of Elliptical Gears with Combined Teeth
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In this study, generation of elliptical gears with different teeth profiles of crowned involute, double circular arc (DCA), and combined (crowned involute with DCA) has been developed. The resulting mathematical equations have been computerized and feed to CNC end mill machine to manufacture elliptical gear models with different profiles. These models are investigated in plane polariscope to show the resulting stresses under certain load. Comparison of photo-elastic stress results shows that combined elliptical gears with DCA side as a loaded side have a minimum resulting contact stress with a reduction percentage of 40% compare with contact stresses in counterpart elliptical gear of involute profile (which is commonly u

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Publication Date
Fri Jan 01 2016
Journal Name
Journal Of Engineering
Theoretical and Experimental Stress Analysis of Cam With Simple Harmonic Motion
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Cams are considered as one of the most important mechanical components that depends the contact action to do its job and suffer a lot of with drawbacks to be predicted and overcame in the design process. this work aims to investigate the induced cam contact and the maximum shear stress energy or (von misses) stresses during the course of action analytically using Hertz contact stress equation and the principal stress formulations to find the maximum stress value and its position beneath the contacting surfaces. The experimental investigation adopted two dimensions photoelastic technique to analyze cam stresses under a plane polarized light. The problem has been numerically simulated using Ansys software version 15 as FE

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Publication Date
Thu Nov 02 2017
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Oxidative Stress and The Activities of Catalase , GST in Thalassemic Patients
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The  study  concentrated  on  measuring  the  lipid  peroxidation marker malon di aldehyde (MDA) in sera of thirty five patients with minor Thalassemia  (Tm), thirty five with major Thalassemia (TM) and thirty five healthy control, their age ranged from (17-30) years. Erythrocytes  enzymes  (Glutathione  -S   - transferase  (GST  )and Catalase) were assayed . The results showed a significant elevation in (MDA) in sera of both patient groups compared to control.

An  increase in the activity of catalase and GST in erythrocytes of

minor Thalassemic patients compared to control was found to be significant. Also, a high significant increase in the

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Publication Date
Mon Jun 17 2019
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
The First Record of Three Species of Dogielius (Monogenea) From Three Cyprinid Fishes From the Greater Zab River, North of Iraq*
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A total of 352 freshwater fishes, belonging to three species of the family Cyprinidae were collected from the Greater Zab river in north of Iraq during the period from November 2000 to the end of November 2001. The inspection of their gills revealed the infection of these fishes with three species of monogenetic trematodes belonging to the genus Dogielius. These species included D. mokhayeri from Aspius vorax with a percentage incidence of 37.5%; D. molnari from Cyprinion macrostomum (33.3%) and D. persicus from Barbus luteus (41.2%). The record of this genus and its three above-named species of the present study are considered as the first record on fishes of Iraq.

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Publication Date
Tue Jun 21 2022
Journal Name
Peerj Computer Science
Performance evaluation of frequency division duplex (FDD) massive multiple input multiple output (MIMO) under different correlation models
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Massive multiple-input multiple-output (massive-MIMO) is considered as the key technology to meet the huge demands of data rates in the future wireless communications networks. However, for massive-MIMO systems to realize their maximum potential gain, sufficiently accurate downlink (DL) channel state information (CSI) with low overhead to meet the short coherence time (CT) is required. Therefore, this article aims to overcome the technical challenge of DL CSI estimation in a frequency-division-duplex (FDD) massive-MIMO with short CT considering five different physical correlation models. To this end, the statistical structure of the massive-MIMO channel, which is captured by the physical correlation is exploited to find sufficiently

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Publication Date
Tue Jan 07 2025
Journal Name
Journal Of Baghdad College Of Dentistry
Evaluation of tissue displacement in posterior palatal seal area with different impression techniques with varying palatal forms
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Background: This study was designed to measure the displacement pattern of posterior palatal seal (pps) area in different forms of the palate and with different impression techniques. Materials and method: This study was used to measure the displacement pattern of (pps)in different palatal shapes by using different impression materials Korrecta wax No.4,Green compound and design of House for pps for each palatal forms by using a 3D Scanner of CAD/CAM and measuring the distance between 2 points in pps area by using Caural Threw. Result: The results show highly significant differences between these techniques and the control group (impression with light body) Conclusion: The physiological impression technique of pps with Korecta wax no.4

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Publication Date
Tue Nov 01 2016
Journal Name
Journal Of Economics And Administrative Sciences
Using Cluster Analysis In Determining The Variables Affecting The Evaluation The Growth Of Children At Different Levels
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In light of the increasing interest in Child-rearing in nurseries and kindergartens and the most important experiences gained by the child at this stage that form the basis for the subsequent stages of her/his physical mental and social growth.

The significance of the research concentrates the need to asses the affecting variables on the child growth to create opportunities for her/him to have intact rearing.

The research also aims to classify these variables at each age level and highlight its moral role.

The problem of the research is the lack of clarity of different variables impact of the child growth in different age levels in nurseries and kindergart

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Publication Date
Mon Oct 01 2012
Journal Name
Iraqi Journal Of Physics
Nanostructural study of Ti-Ni binary alloy prepared by mechanical alloying
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In the present study, a powder mixture of elements Ti and Ni was mechanically alloyed in a high energy ball mill. Microstructure of the nanosized amorphous milled product in different stages of milling has been characterized by X- ray diffraction, scanning electron microscopy and differential thermal analysis. We found that time of mechanical alloying is more significant to convert all crystalline structure to the amorphous phase. Nanocrystalline phase was achieved as a result of the mechanical alloying process. The results also indicates that the phase transformation and the grain size occurs in these alloys are controlled by ball milling time

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Publication Date
Fri Jan 01 2021
Journal Name
Journal Of Mechanical Engineering Research And Developments
Fatigue life of welded joint improvement with various welding principles and shot peening process for AISI 1020 low carbon steel
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