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

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: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:14 Iss:3 (Appropriate regimes of laser drilling models containing melt eject mechanisms)

Authors:
S. S. Kudesia
Department of Physics, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, United Kingdom

P. Solana
Departamento de Matema´tica Aplicada, Universidad Polite´cnica de Madrid, Spain

W. S. O. Rodden
D. P. Hand
J. D. C. Jones
Department of Physics, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, United Kingdom

The significance of melt ejection during various drilling regimes of laser drilling is investigated. The predictions of two analytical models of the drilling process, with and without the melt ejection mechanism, are compared with experimental measurements made using a ...

JLA Vol:18 Iss:3 (Multiscale modeling of solidification during laser cladding process)

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

Laser cladding is an additive manufacturing process in which a laser generates a melt pool on the substrate material while a second material in a powder or wire form is injected into that melt pool. Among all laser manufacturing processes, laser cladding offers the most extensive variety of possibilities to alter a component at its surface. Despite immense potential and advancements, the process model of microstructure evolution and its coupling with macro parameters of the laser cladding process has not been fully developed. To address this...

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:26 Iss:1 (Performance enhancement of aluminum infrared laser welding by preconditioning with nanosecond laser pulses)

Authors:
Philipp von Witzendorff
Anas Moalem
Uwe Stute
Ludger Overmeyer
Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany

We condition the welding zone of the aluminum surface with nanosecond laser pulses prior to welding with infrared laser radiation to increase the process efficiency and weld quality. The high reflectivity of aluminum for infrared laser radiation (95% at 1064 nm) leads to poor process efficiency of aluminum laser welding processes. To increase the workpiece's absorptivity, the welding zone is conditioned with nanosecond laser pulses at a wavelength of 532 nm. The samples are nonalloy, 0.5 mm thick alum...