Preferred Language
Articles
/
alkej-519
Investigation of Thermal Stress Distribution in Laser Spot Welding Process
...Show More Authors

The objective of this paper was to study the laser spot welding process of low carbon steel sheet. The investigations were based on analytical and finite element analyses. The analytical analysis was focused on a consistent set of equations representing interaction of the laser beam with materials. The numerical analysis based on 3-D finite element analysis of heat flow during laser spot welding taken into account the temperature dependence of the physical properties and latent heat of transformations using ANSYS code V.10.0 to simulate the laser welding process. The effect of laser operating parameters on the results of the temperature profile were studied in addition to the effect on thermal stresses  and dimensions of the laser welded workpiece which showed good correlations between analytical and numerical results. It was found that the temperature gradients during laser welding are usually very large and it was viewed that very high temperature at the center of the workpiece, and is decreased very significantly as propagating along the radial direction. Also it found that the thermal residual stresses around the laser spot due to plastic strains were very small and localized within 1.0 mm range. It is concluded that the laser welding process is effective to reduce the welding residual stress. The stresses along the lateral direction of the workpiece changed from compression at the spot under the laser beam and tension away from the spot at the end of welding to tension at the spot under the laser beam and compression away from the spot when it cooled, which are in a good agreement with the published results.

   

View Publication Preview PDF
Quick Preview PDF
Publication Date
Mon Sep 30 2013
Journal Name
Iraqi Journal Of Science
Protective Effect of Vitamin A against Oxidative Stress Caused by Methotrexate
...Show More Authors

Methotrexate (MTX), a folate antagonist agent, is mainly used in treatment of malignant tumors and autoimmune diseases. The present study was undertaken to determine whether antioxidant vitamin (vitamin A) could ameliorate methotrexate induced oxidative stress in male rabbits. Twenty male rabbits were randomly assigned into four groups. Group 1: control group, Group 2: MTX-treated group (received 20 mg/kg MTX intraperitoneally), Group 3: Vit.A treated group received 5000 IU Vit.A orally) and Group 4: MTX+Vit.A treated group received MTX 20 mg/kg plus 5000 IU vit.A). After 4 weeks of treatment, blood samples were collected by cardiac puncture to determine the serum malondialdehyde (MDA), as a good indicator for lipid peroxidation and

... Show More
Publication Date
Tue Oct 01 2019
Journal Name
Journal Of Engineering
Generation and Experimental Stress Analysis of Elliptical Gears with Combined Teeth
...Show More Authors

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

... Show More
View Publication Preview PDF
Crossref
Publication Date
Sun Dec 17 2017
Journal Name
Al-khwarizmi Engineering Journal
Formation of Compressive Residual Stress by Face Milling Steel AISI 1045
...Show More Authors

Abstract

     Machining residual stresses correlate very closely with the cutting parameters and the tool geometries. This research work aims to investigate the effect of cutting speed, feed rate and depth of cut on the surface residual stress of steel AISI 1045 after face milling operation. After each milling test, the residual stress on the surface of the workpiece was measured by using X-ray diffraction technique. Design of Experiment (DOE) software was employed using the response surface methodology (RSM) technique with a central composite rotatable design to build a mathematical model to determine the relationship between the input variables and the response. The results showed that both

... Show More
View Publication Preview PDF
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
...Show More Authors
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
View Publication
Crossref (4)
Crossref
Publication Date
Mon Nov 01 2010
Journal Name
Iraqi Journal Of Physics
Plasma Dynamics and Pulse Shape Rules in Laser Heating of Opaque Targets in Ai
...Show More Authors

A theoretical model is developed to determine time evolution of temperature at the surface of an opaque target placed in air for cases characterized by the formation of laser supported absorption waves (LSAW) plasmas. The model takes into account both plasma dynamics and time variation of incident laser pulse (i.e. pulse shape or profile).Shock tube relations were employed in formulating plasma dynamics over target surface. Gaussian function was chosen in formulating the pulse profile in the present modeling

View Publication Preview PDF
Publication Date
Fri Feb 08 2019
Journal Name
Iraqi Journal Of Laser
Effects of Laser Energy on n-Ge/p-SnS Hetrojunction Diode Detector in Different Environments
...Show More Authors

In the present work, heterojunction diode detectors will be prepared using germanium wafers as a substrate material and 200 nm tin sulfide thickness will be evaporated by using thermal evaporation method as thin film on the substrate. Nd:YAG laser (λ=532 nm) with different energy densities (5.66 J/cm2 and 11.32 J/cm2) is used to diffuse the SnS inside the surface of the germanium samples with 10 laser shots in different environments (vacuum and distilled water). I-V characteristics in the dark illumination, C-V characteristics, transmission measurements, spectral responsivity and quantum efficiency were investigated at 300K. The C-V measurements have shown that the heterojunction were of abrupt type and the maximum value of build-in pot

... Show More
View Publication Preview PDF
Publication Date
Sat Feb 01 2020
Journal Name
Journal Of Engineering Science And Technology (jestec)
Analysis Of Sedimentation In Trunk Sewer With Laboratory Investigation Of Sewage Sediment Characteristics In Baghdad City
...Show More Authors

Sediment accumulated in sewers is a major concern source as it induces numerous operational and environmental problems. For instance, during wet weather flow, the re-suspension of this sediment accompanied by the combined sewer overflow may cause huge pollutant load to the receiving water body. The characteristics of the sewer sediment are important as it shapes its behaviour and determines the extent of the pollution load. In this paper, an investigation of sewer sediment and its characterization is done for a case study in Baghdad city. Sediment depth covers more than 50% of the sewer cross-sectional area; several operational causes are comprised to cause this huge depths of sediment depositions. The testing and analysis of the s

... Show More
Publication Date
Wed Feb 01 2023
Journal Name
Journal Of Engineering
Vertical Stress Prediction for Zubair Oil Field/ Case Study
...Show More Authors

Predicting vertical stress was indeed useful for controlling geomechanical issues since it allowed for the computation of pore pressure for the formation and the classification of fault regimes. This study provides an in-depth observation of vertical stress prediction utilizing numerous approaches using the Techlog 2015 software. Gardner's method results in incorrect vertical stress values with a problem that this method doesn't start from the surface and instead relies only on sound log data. Whereas the Amoco, Wendt non-acoustic, Traugott, average technique simply needed density log as input and used a straight line as the observed density, this was incorrect for vertical computing stress. The results of these methods

... Show More
View Publication Preview PDF
Crossref (1)
Crossref
Publication Date
Fri Nov 01 2024
Journal Name
Human Antibodies
Free radicals and oxidative stress: Mechanisms and therapeutic targets
...Show More Authors
BACKGROUND:

Free radicals are small extremely reactive species that have unpaired electrons. Free radicals include subgroups of reactive species, which are all a product of regular cellular metabolism. Oxidative stress happens when the free radicals production exceeds the capacity of the antioxidant system in the body’s cells.

OBJECTIVE:

The current review clarifies the prospective role of antioxidants in the inhibition and healing of diseases.

METHODS:

Information on oxidative stress, free radicals, reactive oxidant species, and natural and synthetic antioxidants was obta

... Show More
View Publication
Scopus (18)
Crossref (15)
Scopus Crossref
Publication Date
Sun Apr 08 2018
Journal Name
Al-khwarizmi Engineering Journal
Experimental Investigation of the Effect of Curvature Ratio on Heat Transfer in Double Pipe Helical Heat Exchanger
...Show More Authors

Different parameters of double pipe helical coil were investigation experimentally. Four coils were used; three with a curvature ratio (0.037, 0.031, and 0.028) and 11mm diameter of the inner tube while the fourth with 0.033 curvature ratio and 13 mm diameter of the inner tube. The hot water flow in the inner tube whereas the cold water flows in the annulus. The inlet temperatures of hot and cold water are 50 0C and 18 0C respectively. The inner mass flow rate ranges from 0.0167 to 0.0583 kg/s. The results show the Nusselt number increase with increase curvature ratio. The Nusselt number of the coil with 0.037 curvature ratio increases by approximately 12.3 % as compare with 0.028 curvature ratio. The results also r

... Show More
View Publication Preview PDF
Crossref