JLA Vol:16 Iss:2 (Laser short pulse heating of copper: Thermo–elasto–plastic analysis)

Authors:
A. F. M. Arif
B. S. Yilbas
ME Department, KFUPM. Dhahran, Saudi Arabia

Laser short pulse heating of metallic substrates results in excessive electron temperatures in the surface vicinity. This gives rise to nonequilibrium energy transport in the region irradiated by a laser beam. Moreover, the thermomechanical coupling effect should be incorporated into the energy transport equation as lattice site temperature increases. In the present study, laser short pulse heating of copper is considered. The electron kinetic theory approach is employed to model the nonequilibrium heating process while thermomechanical coupling is introduced in the energy transport equation t...

JLA Vol:20 Iss:3 (Diode-pumped solid state laser light sources for confocal laser scanning fluorescence microscopy)

Authors:
Mårten Stjernstro¨m
Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden and Department of Chemistry, Royal Institute of Technology, SE-100 44 Stockholm, Sweden

Fredrik Laurell
Hjalmar Brismar
Department of Applied Physics, Royal Institute of Technology, SE-106 91 Stockholm, Sweden

Diode-pumped solid-state lasers (DPSSLs) have been integrated as light sources in confocal laser scanning microscopy (CLSM). The standard argon ion laser at 488 nm is compared with a DPSSL operating at 473 nm in terms of noise and CLSM image characteristics. The equally high fluorescence image quality togeth...

JLA Vol:9 Iss:3 (High power laser welding in hyperbaric gas and water environments)

Authors:
G. J. Shannon
W. McNaught
W. F. Deans
J. Watson

A hyperbaric laser welding facility has been constructed and the feasibility of high power CO₂ and Nd:YAG laser welding in both high pressure gas and water environments, to simulated water depths of 500 m, has been established. From initial trials on welding through water at atmospheric pressure, it was found that the different absorption characteristics of water to 10.6 μm (CO₂ laser) and 1.06 μm (Nd:YAG laser) radiation proved crucial. The Nd:YAG laser was totally unsuitable as the beam was largely diffused in the water, whereas the CO₂ beam was rea...

JLA Vol:4 Iss:2 (A Systematic Method for the Design of a Multivariable Controller Actuating Power and Speed during a CO₂ Laser Surface Treatment)

Authors:
F. Bataille
J. M. Cerez
D. Kechemair

Temperature control systems actuating laser power and scanning velocity during laser surface hardening have already been presented. This paper exposes a systematic method for the design of a multivariable Linear Quadratic Gaussian controller adapted to this laser treatment. The preliminary identification step and the controller design are included. This corrector insures a better regulation and the generality of the method hopefully allows an easier adaptation to other laser treatments, materials or absorbing coatings.

JLA Vol:14 Iss:2 (Thermomechanical effects in laser microprocessing for dieless metal wire drawing)

Authors:
Yonggang Li
School of Optic/CREOL (Center for Research and Education of Optics and Lasers), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida, 32816-2700

Nathaniel R. Quick
USF Filtration and Separations Group, Inc., 1750 Filter Drive, DeLand, Florida 32724-2045

Aravinda Kar
School of Optic/CREOL (Center for Research and Education of Optics and Lasers), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida, 32816-2700

A new dieless metal fiber drawing process is developed in which a high-precision laser is used to heat the...

JLA Vol:1 Iss:1 (High‐Speed Laser Welding Discontinuities)

Authors:
Charles E. Albright
Shichan Chiang
Department of Welding Engineering, Ohio State University, Columbus, Ohio

JLA Vol:18 Iss:3 (Thermal and microstructural aspects of the laser direct metal deposition of waspaloy)

Authors:
Andrew J. Pinkerton
Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, PO Box 88, Manchester M60 1QD, United Kingdom

Mallikarjun Karadge
Manchester Materials Science Centre, School of Materials, The University of Manchester, Grosvenor Street, Manchester M1 7HS, United Kingdom

Waheed Ul Haq Syed
Lin Li
Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, PO Box 88, Manchester M60 1QD, United Kingdom

A potential problem in applying the laser direct metal deposition (LDMD) technique to the f...

JLA Vol:23 Iss:2 (Recent advances in laser surface treatment of titanium alloys)

Authors:
J. J. Candel
V. Amigo´
ITM Instituto de Tecnologia de Materiales, UPV, Valencia, Spain

This paper reviews progress over the last five years in the field of laser surface modification of titanium alloys. The authors analyze the effect of new laser technologies and new materials as tools for improving surface properties—specifically, biocompatibility and resistance to wear, corrosion, and high temperatures. The authors discuss the effect of laser processing parameters on the microstructure and compare the results obtained by various researchers. Therefore, an overview of the difficulties involved in the laser processing of titanium is provided with a di...

JLA Vol:7 Iss:4 (Laser cutting of thick sectioned steels using gas flow impingement on the erosion front)

Authors:
P. M. Ilavarasan
P. A. Molian
Department of Mechanical Engineering, Iowa State University, Ames, IA 50011, U.S.A.

An off‐axial gas jet has been developed that has the potential to extend the laser's effectiveness by improving the rate at which parts can be machined, producing high‐quality surfaces, enhancing the cutting thickness, and adding to the range of materials that can be machined. In laser cutting, an erosion front (liquid–gas region) forms at the momentary end of the cut. Laser heating, exothermic reactions and shear force between the gas flow and the molten layer dictate the material removal rates. The principle of the off‐axi...

JLA Vol:16 Iss:4 (Dimensional and material characteristics of direct deposited H13 tool steel by CO₂ laser)

Authors:
J. Choi
Y. Hua
Department of Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri, Rolla, Missouri 65409-1060

Laser aided direct metal/material deposition process builds metal parts layer-by-layer directly from the computer aided design representation. Success of this technology in the die and tool industry depends on the parts quality to be achieved. To get designed geometric dimensions and material properties, delicate control of the process variables such as laser power, spot diameter, traverse speed, and powder mass flow rate is critical. With a closed loop optical height control system, the dimensional accuracy was achieved ...