JLA Vol:1 Iss:4 (Optical Methods in Flow Visualization)

Authors:
Wen‐Jei Yang
Yi Chen
Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan 48109

Optical techniques for flow visualization are presented, including light‐sheet flow visualization, shadowgraphy, schlieren method, interferometry, holography, speckle photography, laser‐induced fluorescence and thermography. The principles of these methods are briefly described and the examples of their applications to flow visualization are given.

JLA Vol:18 Iss:1 (Effect of oxygen in ambient atmosphere on penetration characteristics in single yttrium–aluminum–garnet laser and hybrid welding)

Authors:
Yasuaki Naito
Masami Mizutani
Seiji Katayama
Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Welding with a yttrium–aluminum–garnet (YAG) laser only or with hybrid source combined with a YAG laser and a TIG arc was carried out on Type 304 stainless steel plate with low S content in the air or in the chamber with Ar gas including 0%–15% oxygen gas. It was confirmed in both laser and hybrid welding that the penetration and geometry of welds depended upon the volume of the oxygen in the ambient atmosphere, and that a pronounced “nail head” disappeared in a weld...

JLA Vol:22 Iss:3 (Evaluation criterion and closed-loop control of penetration status during laser-MIG hybrid welding)

Authors:
Yongqiang Zhang
Shougang Research Institute of Technology, Beijing 100043, Peoples Republic of China

Peng Wen
Jiguo Shan
Yuanqing Shuang
Wuzhu Chen
Department of Mechanical Engineering, Tsinghua University Beijing 100084, Peoples Republic of China

Laser-MIG hybrid welding is an advanced joining process and is widely applied in various industries. It is important to make sure the plate is fully penetrated with an appropriate weld formation in practical applications. In this paper, 3 kW CO₂ laser and pulse MIG machine were used to compose the laser-MIG hybrid welding equipment to make butt weld of stainless...

JLA Vol:25 Iss:4 (On the exposure limits for extended source multiple pulse laser exposures)

JLA Vol:9 Iss:2 (Laser cladding with a pulsed Nd:YAG laser and optical fibers)

Authors:
M. Brandt
D. A. Scott
S. B. Emms
J. M. Yellup

A new laser cladding technique for producing wear and corrosion resistant surfaces on engineering components is reported. The technique involves the combination of the pre‐placed and injected powder delivery methods for producing clad layers. The clad layers were formed with a pulsed Nd:YAG laser and optical fibers. The results using a nickel‐based alloy (Hastelloy C) indicate that uniform clad layers in excess of 1 mm in thickness can be achieved in a single pass with 240 W average power incident on the workpiece. The laser beam was delivered through a step‐index glass ...

JLA Vol:4 Iss:3 (High Tech or High Risk — The laser on your manufacturing floor)

Authors:
Tom Wiley
Lumonics Industrial Products Division

JLA Vol:16 Iss:1 (Laser-induced electrochemical characteristics of aluminum alloy 2024-T3)

Authors:
Olga Kachurina
Tammy L. Metroke
Kai Dou
Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078

Laser-induced surface modification of aluminum alloy 2024-T3 was investigated as laser intensity dependence of surface composition and patterning related to electrochemical characteristics using techniques of environmental scanning electron microscopy (ESEM), potentiodynamic scan, and electrochemical impedance spectroscopy (EIS). Analysis of surface composition using ESEM and EIS indicated that laser fluences in a range of 1.1–1.3 J/cm² were found to preferentially reduce the copper concentration in the alloy surf...

JLA Vol:20 Iss:2 (Review of exposure limits and experimental data for corneal and lenticular damage from short pulsed UV and IR laser radiation)

Authors:
Karl Schulmeister
Austrian Research Centers, A-2444 Seibersdorf, Austria

David H. Sliney
US Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Ground, Maryland 21010-5422

John Mellerio
Department of Ophthalmology, Rayne Institute, St. Thomas’ Hospital, London, SE1 7EH, United Kingdom

David J. Lund
Bruce E. Stuck
US Army Medical Research Detachment, Walter Reed Army Institute of Research, Brooks City-Base, San Antonio, Texas 78235-5108

Joseph A. Zuclich
Northrop Grumman Information Technology, San Antonio, Texas 78288-1330

Laser exposure limits as ...

JLA Vol:23 Iss:2 (Microcomputed tomography analysis of intralayer porosity generation in laser direct metal deposition and its causes)

Authors:
M. Naveed Ahsan
Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester M13 9PL, United Kingdom

Robert Bradley
Henry Moseley X-ray Imaging Facility, School of Materials, University of Manchester, Grosvenor Street, Manchester M13 9PL, United Kingdom

Andrew J. Pinkerton
Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester M13 9PL, United Kingdom

Laser direct metal deposition has wide application in the areas of rapid manufacturing, surface coating, and compon...

JLA Vol:9 Iss:6 (Scaling laws for thick‐section cutting with a chemical oxygen–iodine laser)

Authors:
A. Kar
J. A. Rothenflue
W. P. Latham

Almost all laser‐assisted materials processing involves melting, vaporization and plasma formation which affect the utilization of laser energy for materials processing. To account for the effect of these phases, an effective absorptivity is defined, and a simple mathematical model is developed for the cutting of thick‐section stainless steel using a high power chemical oxygen—iodine laser (COIL). The model is based on an overall energy balance, and it relates the cutting depth with various process parameters that can be used to predictively scale the laser materials processing performance to ...