research centers


Search results: Found 7

Listing 1 - 7 of 7
Sort by

Article
Analysis of Temperature and Residual Stress Distribution in CO2 Laser Welded Aluminum 6061 Plates Using FEM
تحليل توزيع درجات الحرارة والاجهادات المتبقية في صفائح الالمنيوم 6061الملحومة باليزر باستخدام طريقة العناصر المحددة

Author: Sanaa Numan Mohammed سناء نعمان محمد
Journal: Al-Khwarizmi Engineering Journal مجلة الخوارزمي الهندسية ISSN: 18181171 23120789 Year: 2011 Volume: 7 Issue: 3 Pages: 48-58
Publisher: Baghdad University جامعة بغداد

Loading...
Loading...
Abstract

This paper develops a nonlinear transient three-dimensional heat transfer finite element model and a rate independent three-dimensional deformation model, developed for the CO2 laser welding simulations in Al-6061-T6 alloy. Simulations are performed using an indirect coupled thermal-structural method for the process of welding. Temperature-dependent thermal properties of Al-6061-T6, effect of latent heat of fusion, and the convective and radiative boundary conditions are included in the model. The heat input to the model is assumed to be a Gaussian heat source. The finite element code ANSYS12, along with a few FORTRAN subroutines, are employed to obtain the numerical results. The benefit of the proposed methodology is that it offers the capability of optimizing laser welding process, and also provides a reliable estimation of the developed temperatures, as well as the thermal stress (residual stress) and strain fields reducing the experimental effort.

في هذا البحث تم تطوير نموذج ثلاثي الابعاد لاخطي لنمذجة عملية الانتقال الحراري والتشوه الميكانيكي الحاصل في عملية اللحام بالليزر في سبائك الالمنيوم 6061-T6 . تم استخدام اسلوب المحاكاة الحراري والهيكلي المقترن اللامباشر في عملية اللحام. ولكون النموذج المقترح هو لاخطي فقد استخدمت خواص حرارية وميكانيكية متغيرة مع درجة الحرارة مع الاخذ بنظر الاعتبار الظروف المحيطة بالعملية مثل الحمل الحراري والاشعاع. تم التحليل باستخدام برنامج ANSYS12 مع بعض البرامج الداعمة والتي كتبت بلغة FORTRAN .الفائدة المتوخاة من هذا البحث هو انه يمكن اعتماد المنهجية المقترحة في دراسة وتحليل عملية اللحام بالليزر وما يرافقها من تشوهات واجهادات حرارية وبالتالي الحصول على عملية لحام مثلى.


Article
The Effect of Laser Welding on the Ten-sile Strength and Radiographic Analysis of Co-Cr Repaired Joints

Authors: Abdullah J Mohammed --- Nazar Gh Jameel --- Nadira A Hatim
Journal: Al-Rafidain Dental Journal مجلة الرافدين لطب الأسنان ISSN: 18121217 Year: 2012 Volume: 12 Issue: 19 Pages: 1-13
Publisher: Mosul University جامعة الموصل

Loading...
Loading...
Abstract

Aims: To evaluate the effect of laser welding and arc welding on the ultimate tensile strength, radio-graphic appearance of the joints, and microscopic porosities in the fractographs. Four joining methods have been used, laser welding, and arc welding using three types of electrodes (iron, stainless steel, and brass). Effect of surface roughness on the aforementioned properties was evaluated. Materials and Methods: Three specimens as-cast control group, seventy two specimens were treated by polishing, laser, and sandblasting, and joined with the four joining methods. Joints examined by radiograph and porosities were measured by Dimax software program, their ultimate tensile strength, and strain was tested, and the microscopic porosities in the fractographs were measured using AutoCAD software program. Three cobalt chromium bars from the third group were joined to three stainless steel bars from the fourth group of the same diameter to test the ultimate tensile strength, and strain of the dissi-milar alloys. Results: Laser welded and brass soldered joints had significantly lower ultimate tensile strength and strain when compared to the control group, while the iron, and stainless steel soldered joints had insignificant differences in the ultimate tensile strength and strain when compared to the control group. Results shown that the iron and stainless steel soldered samples fractured in the heat affected zone while the brass soldered and laser welded samples fractured in the weld zone. The iron and stainless steel soldered joints had superior mechanical properties when compared with the control group. Laser welding of dissimilar alloys had the lowest mechanical properties among all techniques. Conclusions: revealed that laser welding was the most precise technique used in the current study. Weld fractures shown less tensile strength average and more brittle behavior. Radiographic properties had no influence on the mechanical properties of the joints.


Article
HAZ and Melt Limits of 3-D CO2 Laser welding

Authors: A.K. Hamoudi --- W.K. Hamoudi --- S.A. Salih
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2011 Volume: 7 Issue: 2 Pages: 11-17
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

Loading...
Loading...
Abstract

An analytical and numerical 3-D model for keyhole CO2 laser welding of thick C/Mn steel sheets is constructed to study the heat affected zone (HAZ) and melt limits. Simulation results are compared with experimental investigations under variety of laser material processing conditions. The model combines a moving point source for the top part of the weld and a moving line source for the parallel sided region of the weld. The good match of theoretical and experimental results makes the model a good tool to predict the HAZ volume in which microstructure changes may occur. Such prediction is useful in the investigation of hardening and the cracks formation during laser welding.


Article
Modeling of the Preheating Effect on Keyhole Laser Welding Efficiency

Authors: K.S. Khashan --- O.A. Hamadi
Journal: Iraqi Journal of Applied Physics Letters الرسائل العراقية في الفيزياء التطبيقية ISSN: 1999656X Year: 2008 Volume: 1 Issue: 1 Pages: 10-15
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

Loading...
Loading...
Abstract

In this work, results of a mathematical analysis of the role of workpiece preheating in laser keyhole welding were presented. This analysis considered the steady-state welding as well as certain range of boundary conditions over which preheating effect would be indicated. This work is an attempt to interpret the role of preheating to increase welding depth and perform keyhole welding with high quality using physical and thermal properties of steel alloys.


Article
Modeling of 3-D Keyhole CO2 Laser Welding of Steel

Authors: W.K. Hamoudi --- A.K. Hamoudi --- S.A. Salih
Journal: Iraqi Journal of Applied Physics المجلة العراقية للفيزياء التطبيقية ISSN: 18132065 23091673 Year: 2010 Volume: 6 Issue: 1 Pages: 15-23
Publisher: iraqi society for alternative and renewable energy sources and techniques الجمعية العراقية لمصادر وتقنيات الطاقة البديلة والمستجدة

Loading...
Loading...
Abstract

A mathematical 3-D model for keyhole CO2 laser welding of thick C/Mn steel sheets under variety of laser material processing conditions is presented. The analysis yields profile of the melt pool and compare it with experiments. The model combines a moving point source for the top part of the weld and a moving line source for the parallel sided region of the weld (stem). This concept produces weld profiles that have good qualitative agreement with the experiments. Mathematical model and computer program were constructed to solve two basic heat conduction equations for the moving point and line sources. The excellent match of theoretical and experimental weld profiles will make this work a good candidate for laser welding prediction in robotic networks.


Article
Parametric Optimization of Pulsed Nd:YAG Laser Lap Welding of Stainless Steel ASTM A240/ 316L with Carbon Steel ASTM A570/Gr30

Author: Thaier A. Tawfiq
Journal: AL-NAHRAIN JOURNAL FOR ENGINEERING SCIENCES مجلة النهرين للعلوم الهندسية ISSN: 25219154 / eISSN 25219162 Year: 2017 Volume: 20 Issue: 1 Pages: 27-35
Publisher: Al-Nahrain University جامعة النهرين

Loading...
Loading...
Abstract

This work describes seam welding process using dissimilar ferrous metals by pulsed Nd:YAG. The main objective of this work is to achieve the best welding conditions. This imposes careful selection for the welding parameters and inevitably the well design of experiment (DOE). Sheets of ASTM A240/316L stainless steel to ASTM A570/Gr30 carbon steel all of 0.5 mm in thickness were lap welded. Different pulse energies or the related peak power, pulse duration, pulse repetition rate, and welding speeds were used. Moreover, different welding speeds were controlled by the employed manipulator. The laser beam spot diameter and the standoff distance were fixed. Experimental results are supported by the computational 2D and 3D models. In this article response surface methodology (RSM) was applied to design the experiment and obtain the best parameters through a set of mathematical models that define the weld characteristics. The results show that the best joint in term of joint strength is obtained at 31.9 J pulse energy (related to 5.5 kW peak power and 5.8 ms pulse duration), power density of 1.43×106 W/cm2, 1.5 Hz pulse repetition rate, and 0.5 mm/s welding speed.


Article
Modeling of Continues Laser Welding for Ti-6Al-4V Alloys Using COMSOL Multiphysics Software

Authors: Haneen A. Salman --- Kadhim A. Hubeatir --- Mohammed M. AL-Kafaji
Journal: Engineering and Technology Journal مجلة الهندسة والتكنولوجيا ISSN: 16816900 24120758 Year: 2018 Volume: 36 Issue: 8 Part (A) Engineering Pages: 914-918
Publisher: University of Technology الجامعة التكنولوجية

Loading...
Loading...
Abstract

A model for laser welding process using finite element method, the model was used for this work using the COMSOL Multiphysics software to predict the distribution of the temperature in the joint and to show the four welding zones (the melting zone, partial melting zone, zone affected by heat, and the material base). CO2 continues (CW) Laser used in the model welding thin sheets of titanium alloy Ti-6Al-4V. The results of this simulation work have been compared with the experimental works to show good agreement.

Listing 1 - 7 of 7
Sort by
Narrow your search

Resource type

article (7)


Language

English (6)

Arabic and English (1)


Year
From To Submit

2018 (1)

2017 (1)

2012 (1)

2011 (2)

2010 (1)

More...