JLA Vol:14 Iss:3 (Effects of laser welding parameters on magnetic materials with the aid of a mechatronic measuring system)
Hussein A. Abdullah
School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1, Canada
Chris R. Chatwin
School of Engineering, University of Sussex, Brighton BN1 9QT, United Kingdom
This article reports results from an experimental investigation into laser welding of ferromagnetic material, which, for example, is of interest to the European Space Agency. The effects of laser welding power and translation velocities on the magnetism of ferromagnetic materials were studied. An automated system using a Hall effect transducer was constructed to measure the magnetic field transverse to the laser weld before welding, immediately after welding and thr...
Marc D. Friedman
Hans I. Bjelkhagen
Biomedical Engineering, Northwestern University, Evanston, Illinois
JLA Vol:18 Iss:3 (Femtosecond laser production of metal surfaces having unique surface structures that are broadband absorbers)
Dennis R. Alexander
Center for Electro Optics and Electrical Engineering Department, University of Nebraska-Lincoln, 248 N WSEC, Lincoln, Nebraska 68588-0511
Femtosecond laser induced modification of surface structure and the optical properties of metals are studied. A Ti:sapphire femtosecond laser is used for ablating bulk aluminum 2024 T3 alloy and highly pure neutron activation quality gold metal samples at different laser irradiation parameters. The ablation parameters are optimized for the two metals to form a low reflection surface in the wavelength range of 0.3–50 μm. “Blac...
Laser Zentrum Hannover e.V., Hollerithallee 8, D-30419 Hannover, Germany
Lehrstuhl fuer Laseranwendungstechnik, Ruhr-Universitaet Bochum, Universitaetsstr. 150, D-44780 Bochum, Germany
Surface texturing is an established method for altering the structure of a surface. All known methods deal with material removal. For applications where only small walls remain on the surface, this means that most of the surface must be treated. In this paper, a new approach is presented in which texturing and laser cladding are co...
Gary K. Lewis
David A. Cremers
W. W. Duley
Physics Department, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1
In many laser applications it is the conversion of photon energy to heat that drives the process. Heat transfer theory accurately describes the effects produced, and other aspects of thermodynamics need not generally be considered explicitly. The highly nonequilibrium nature of laser materials processing operations can usually be ignored once the heat transfer problem is defined. However, “equilibrium” is a concept that is basic to thermodynamics, and so it is useful to examine this concept in the context of traditional laser materials processing applications. Some of the ass...
JLA Vol:21 Iss:2 (Visualization of refraction and attenuation of near-infrared laser beam due to laser-induced plume)
Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan
This study was performed to obtain a fundamental knowledge of the interaction between a near-infrared laser beam and an induced plume during welding. The plume was characterized by spectroscopy, and the effect and mechanism of the laser-induced plume on the refraction and/or attenuation were investigated by high-speed video observation of the plume and the probe laser, and power meter measurement of the fiber probe laser beam of 1090 nm wavelength which pa...
The acoustic emissions from laser lap welds in stainless steel sheet were recorded and analyzed. The acoustic signals emanating from the weld were sensed with an instrument microphone and analyzed using short‐time Fourier spectra to characterize their time‐frequency distributions. It was determined that the acoustic spectrum of good‐quality, full‐penetration welds could be differentiated from the spectra of poor‐quality welds, defined as either partial‐penetration welds or welds having a gap between the sheets being joined. A novel, relatively simple class...
H. W. Bergmann
Forschungsverbund Lasertechnologie Erlangen (FLE), Martensstr. 5, 8520 Erlangen, West Germany
Aluminum alloys are used extensively in aerospace structures because of their high strength‐to‐weight characteristics. Unfortunately, these alloys are difficult to cut by laser processing. This behavior stems from: 1) their affinity for atmospheric gases, 2) their tendency to form high melting point reaction products and 3) the marked difference between their solidus and liquidus temperatures, which leads to formation of a mushy zone during cutting. This paper describes the results of a program directed t...
JLA Vol:15 Iss:2 (Automatic detection of lack of fusion defects in CO<sub>2</sub> laser gear welding)
Department of Mechanical, Aerospace, and Industrial Engineering, Ryerson University, Toronto, Ontario M5B 2K3, Canada
Department of Mechanical Engineering, Queen’s University, Kingston, Ontario K7K 3N6, Canada
Powerlasers Ltd., Advanced Technologies Centre, Kitchener, Ontario N2G 2Y5, Canada
Laser welding is becoming increasingly important in the automotive industry and quality of the weld is critical for a successful application. In many cases the increase in welding speed provided by laser welding has resulted in the need for an automated, on-line weld monitoring system....
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