• JLA Vol:3 Iss:3 (Fusion Zone Structures in Laser Welded Al‐SiC Composites)


    Authors:
    Mary H. McCay
    T. Dwayne McCay
    Narendra B. Dahotre
    C. Michael Sharp
    Center for Laser Applications, University of Tennessee Space Institute, Tullahoma, Tennessee 37388


    Metal matrix composites continue to be desirable structural materials but difficulties in joining limit their usefulness. This paper describes the results of a study on the laser welding of A356‐AI/SiC particulate composites. Three separate processing regimes are identified based upon analytical model predictions and metallographic analysis of the solidification structures.

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  • JLA Vol:17 Iss:3 (Experimental study of CO<sub>2</sub> laser welding inside a groove&mdash; Application to high thickness laser welding)


    Authors:
    M. Hamadou
    R. Fabbro
    F. Coste
    S. Slimani
    GIP GERAILP/LALP (CNRS) 16 bis, Av. Prieur de la Coˆte d’Or 94114 Arcueil, France


    Laser welding inside a groove has to be considered when a high thickness material is welded. The use of a groove shape allows the access of the laser beam to the lower part of the groove. The choice of the groove geometry (groove width, depth, or aperture angle), as well as the assist gas setup (leading, trailing or backside protection) are then significant operating parameters for the process control. In this study, U- and V-shaped groove welding with a CO2 laser was investigated. The U-shaped ...

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  • JLA Vol:22 Iss:1 (Laser roll welding of dissimilar metal joint of zinc coated steel to aluminum alloy)


    Authors:
    Hitoshi Ozaki
    Muneharu Kutsuna
    Graduate School of Engineering, Nagoya University, 1, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan

    Shigeyuki Nakagawa
    Kenji Miyamoto
    Research Center, Nissan Motor Co., Ltd., 1, Natsushima-cho, Yokosuka-shi, Kanagawa 237-8523, Japan


    There is a subject to reduce the weight of car body by replacing steel to aluminum alloys as some structural body parts for improving fuel consumption and suppressing CO2 generation. As one of the solutions, the hybrid body structure concept using aluminum alloys and high strength steels is proposed recently. However, it is well known that fusion welding of st...

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  • JLA Vol:1 Iss:3 (Chemical Composition of Laser&hyphen;Tissue Interaction Smoke Plume)


    Authors:
    John M. Kokosa
    GMI Engineering & Management Institute, Flint, Michigan 48504 U.S.A.

    John Eugene
    Beckman Laser Institute, Irvine, California 92715 U.S.A.


    Lasers are assuming an increasingly important role in surgical procedures. However, several studies have shown that the smoke produced by laser&hyphen;tissue interaction is an airway irritant. Preliminary studies in our laboratories have shown that potentially hazardous chemicals, including benzene, formaldehyde and acrolein are present in the smoke plume resulting from CO2 and Nd:YAG laser interaction with animal tissue, even at low power densities. Since these chemicals are classified a...

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  • JLA Vol:24 Iss:1 (Silicon(IV) phthalocyanine-loaded-nanoparticles for application in photodynamic process)


    Authors:
    Andreza Ribeiro Simioni
    Fernando L. Primo
    Antonio Claudio Tedesco
    Array


    The aim of this study was to evaluate the potential application of biodegradable nanoparticles containing a photosensitizer in photodynamic therapy. The poly (D,L lactic-co-glycolic acid) nanoparticles were studied by steady-state techniques, time-resolved fluorescence, and laser flash photolysis. The external morphology of the nanoparticles was established by scanning electron microscopy, and the biological activity was evaluated by in vitro cell culture by 3-(4,5 dimethyl-thiazol-2,5 biphenyl) tetrazolium bromide assay. The particles were spherical in shape exhibiting ...

    $25.00

  • JLA Vol:6 Iss:2 (Laser safety standards in Europe)


    Authors:
    B. A. Tozer
    Lasermet Ltd and City University, London, U.K.


    This paper reviews the present state of the standards&hyphen;making process in Europe, explaining such arcane terms as ‘CEN’, ‘CENELEC’, ‘Euronorm’ and ‘directive’. Standards&hyphen;making bodies in Europe work to strict guidelines with regard to their relationship to member countries of the EEC and EFTA, and work closely with the international standards bodies, IEC and ISO, to minimize duplication of effort and to ensure minimum conflict with international standards. The current situation with regard to laser safety standards in Europe is reviewed, and the author specul...

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  • JLA Vol:15 Iss:4 (Design and performance of multilevel phase fan-out diffractive optical elements for laser materials processing)


    Authors:
    Keiji Fuse
    Takayuki Hirai
    Toshihiko Ushiro
    Takeshi Okada
    Kenichi Kurisu
    Keiji Ebata
    Itami R&D Laboratories, Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024, Japan


    A multilevel phase fan-out diffractive optical element (DOE) has been developed and introduced into various kinds of laser materials processing such as drilling, cutting, welding, and soldering. The larger the number of arrayed spots the DOE generates on the surface of the workpiece, the more sensitive the intensity uniformity of the spots becomes to fabrication errors, which are deviations between designed and fabric...

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  • JLA Vol:20 Iss:1 (Optimization of production rate in diode laser hardening)


    Authors:
    Edoardo Capello
    Barbara Previtali
    Dipartimento di Meccanica, Politecnico di Milano, Via Bonardi 9, 20133 Milano, Italy


    The present paper is a contribution to the definition of optimal laser hardening conditions with production rate as the main goal. When the part to be treated is given, the optimization problem can be expressed in terms of minimal execution time subjected to two constraints: the depth of treatment and hardness of transformed layer. When the analytical expression of the objective function and the constraints was determined, the feasibility area was described and analyzed. Finally, an optimization algorithm was applied to identify the optimal solut...

    $25.00

  • JLA Vol:8 Iss:4 (Some aspects of laser heating of engineering materials)


    Authors:
    B. S. Yilbas
    A. Z. Al&hyphen;Garni
    Mechanical Eng. Dept., KFUPM, P.O. Box 1913, Dhahran, Saudi Arabia


    Laser induced heating processes are important when a laser is used as a machine tool in industry, since the quality of the machining process strongly depends on the heating mechanism. The present study examines a heat transfer model that provides useful information on the laser induced interaction mechanism. Steady state and time dependent heating models are introduced and temperature profiles inside the materials are predicted. Using appropriate assumptions, the time for the surface temperature to reach 90&percnt; of its steady state value is estimated. To valid...

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  • JLA Vol:2 Iss:2 (Laser Induced Photochromic Flow Visualization)


    Authors:
    Thomas McWaid
    Ekkehard Marschall
    Department of Mechanical Engineering, University of California, Santa Barbara, CA 93106


    The photochromic flow visualization technique has been utilized to study several different liquid flows. The technique utilizes radiachromic dyes that can be dissolved in a number of liquids. The resulting dye&hyphen;solvent solutions remain colorless in the absence of ultraviolet radiation; however, the solutions turn dark blue when exposed to ultraviolet light. A nitrogen pulse laser has been constructed for use as source of ultraviolet radiation. When sharply focused, the emitted beam of ultraviolet light produces a very narrow, well define...

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