• 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...


  • JLA Vol:18 Iss:3 (Femtosecond laser production of metal surfaces having unique surface structures that are broadband absorbers)

    Neha Singh
    Dennis R. Alexander
    John Schiffern
    David Doerr
    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...


  • JLA Vol:8 Iss:1 (Frequency–time characteristics of air‐borne signals from laser welds)

    D. Farson
    K. Hillsley
    J. Sames
    R. Young

    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...


  • JLA Vol:24 Iss:2 (Synthesis of nitrogen-doped diamond films using vibrational excitation of ammonia molecules in laser-assisted combustion flames)

    L. S. Fan
    Z. Q. Xie
    J. B. Park
    X. N. He
    Y. S. Zhou
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511

    L. Jiang
    Department of Mechanical and Automation Engineering, Beijing Institute of Technology, Beijing 100081, People’s Republic of China

    Y. F. Lu
    Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511

    Nitrogen-doped diamond was synthesized in open air using laser-assisted combustion flame method. A wavelength-tunable CO2 laser was used to resonantly excite the vibration mod...


  • JLA Vol:6 Iss:3 (Acoustic emission response of soda lime glass after a single Nd‐YAG laser pulse)

    R. Harrysson
    P. Vomacka
    Department of Engineering Materials, Luleå University of Technology, S‐951 87 Luleå, Sweden

    When machining brittle solids with a laser, crack formation can occur in the material around the irradiated area causing a strength reduction of the machined material. The purpose of this work was to study a well known brittle material (soda lime glass) by means of acoustic emission (AE) in order to investigate the correlation between visually observed crack formation and detected AE energy released by the crack formation in the material. During and after irradiation of soda lime glass with an Nd‐YAG laser pulse, the number...


  • JLA Vol:15 Iss:1 (Dual laser beam modification of high alumina ceramics)

    D. Triantafyllidis

    J. R. Bernstein
    Corrosion and Protection Centre, University of Manchester Institute of Science and Technology, Manchester M60 1QD, United Kingdom

    L. Li
    Department of Mechanical, Aerospace and Manufacturing Engineering, University of Manchester Institute of Science and Technology, Manchester M60 1QD, United Kingdom

    F. H. Stott
    Corrosion and Protection Centre, University of Manchester Institute of Science and Technology, Manchester M60 1QD, United Kingdom

    Alumina-based refractory materials are extensively used in high-temperature applications, such as linings in waste incinerators. A sign...


  • JLA Vol:19 Iss:2 (Femtosecond laser microstructuring of hot-isostatically pressed zirconia ceramic)

    Niko Ba¨rsch
    Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover, Germany

    Kristian Werelius
    Department of Prosthodontics, Johann Wolfgang Goethe University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt/Main, Germany

    Stephan Barcikowski
    Fernando Liebana
    Uwe Stute
    Andreas Ostendorf
    Laser Zentrum Hannover, Hollerithallee 8, 30419 Hannover, Germany

    Densely sintered zirconia ceramics—especially hot-isostatically pressed forms of zirconia ceramics like hot-isostatically pressed yttria-stabilized tetragonal zirconia polycrystal (HIP Y-TZP)—have the potential of superseding conve...


  • JLA Vol:26 Iss:1 (Investigation on reducing distortion by preheating during manufacture of aluminum components using selective laser melting)

    Damien Buchbinder
    Wilhelm Meiners
    Norbert Pirch
    Konrad Wissenbach
    Fraunhofer Institute for Laser Technology (ILT), Aachen 52074, Germany

    Johannes Schrage
    Chair for Laser Technology, RWTH Aachen University, Germany 52024, Aachen

    The additive manufacturing process selective laser melting (SLM) can be used to directly produce functional components made out of metal. During the construction process, however, thermally induced residual stress occurs due to the layered build-up and the local input of energy by means of a focused laser beam, which can lead to distortion of the component or sections of the component itself....



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