• JLA Vol:17 Iss:4 (Effect of steel composition on the laser cutting behavior of 25-mm-thick plates)


    Authors:
    M. Manohar
    R. L. Bodnar
    Mittal Steel USA R&D, Bethlehem, Pennsylvania

    R. I. Asfahani
    U.S. Steel Research and Technology Center, Monroeville, Pennsylvania

    N. Chen
    C. Huang
    Caterpillar Technical Center, Peoria, Illinois


    Attempts were made to gain a better understanding of the effects of steel composition and thermophysical properties, such as solidus and liquidus temperatures, heat of oxidation, surface tension, viscosity and thermal conductivity, on laser-cutting behavior. Laboratory-produced heats containing varying levels of C, S, Si, Cu, Ni, Cr, and Mo were hot-rolled to 32-mm-thick plates. Laser cutt...

    $25.00

  • JLA Vol:22 Iss:1 (Surface effects of alumina ceramics machined with femtosecond lasers)


    Authors:
    J. Meeker
    A. E. Segall
    V. V. Semak
    Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802


    Laser machining is now an accepted method for shaping and modifying ceramics and is rapidly replacing other methods such as grinding and etching. In fact, new innovations such as short pulsed or femtosecond lasers have drastically decreased the amount of unwanted damage associated with laser machining. However, laser machining does still alter the surface and can change the flaw populations and the strength. In order to investigate this effect, the flaw populations and strengths of both unaltered and femtosecond...

    $25.00

  • JLA Vol:1 Iss:2 (A Study in Surface Alloying of Titanium Alloys)


    Authors:
    A. Bharti
    R. Sivakumar
    Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad‐500 258, India

    D. B. Goel
    Department of Metallurgical Engineering, University of Roorkee, Roorkee‐247 667, India


    A 5 KW CW CO2 laser has been used to alloy the surface of Ti6Al4V alloy with carbon. As a result the average microhardness was increased from 365 to 600 kg/mm.2 Compositional inhomogeneity was observed on the alloyed surface, however the compositional inhomogeneity index reduced considerably by cross scanning with defocused laser beam. Surface roughness of the alloyed surface was also studied and the roughn...

    $25.00

  • JLA Vol:23 Iss:1 (Picosecond laser-induced color centers in glass optics)


    Authors:
    David Ashkenasi
    Andreas Lemke
    Applied Laser Technology, Laser- and Medical-Technology Berlin (LMTB) GmbH, Fabeckstr. 60-62, 14195 Berlin, Germany


    It is known that ionizing radiation (x ray, gamma rays, and electrons) can induce numerous changes in the physical properties of glasses. The most obvious effect is visible coloration, which is caused by the accumulation of color centers (defects) in the irradiated volume. The application of such induced color centers has prompted a renewed interest since they can be generated and bleached reversibly. We present results on laser-induced color centers in different types of glasses using picosecond laser pulses. By applyi...

    $25.00

  • JLA Vol:7 Iss:3 (Study of liquid and vapor ejection processes during laser drilling of metals)


    Authors:
    Bekir S. Yilbas¸
    Department of Mechanical Engineering, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia


    In an experimental investigation of laser–metal interaction, one of the important parameters is the propagation velocity of the liquid–vapor interface. The quantity appears as a direct result of the theoretical examination of the interaction and may be used to test the accuracy of the theory. Consequently, in the present study, the nature of the interaction mechanism between a pulsed laser beam and metals is examined using streak photographs of the ejecta from four metals: titanium, tantalum, nickel, and EN58B stainless steel. It...

    $25.00

  • JLA Vol:15 Iss:4 (Solution of two-temperature thermal diffusion model of laser–metal interactions)


    Authors:
    S. R. Vatsya
    Kuljit S. Virk
    Integrated Manufacturing Technologies Institute, National Research Council of Canada, 800 Collip Circle, London, Ontario N6G 4X8, Canada


    The two temperature coupled equations, modeling thermal diffusion during laser-induced ablation of metals, are solved under the assumptions that the electron and the lattice heat capacities, and the thermal conductivity remain constant in the process. In view of its practical value, the solution is initially obtained for the energy sources with a Gaussian distribution. The solution is then generalized to include a larger class of source terms for comparison with other results. Present analysis is vali...

    $25.00

  • JLA Vol:20 Iss:1 (Experimental investigation of remote welding with CO<sub>2</sub> and Nd:YAG laser-based systems)


    Authors:
    George Tsoukantas
    Aristidis Stournaras
    George Chryssolouris
    Laboratory for Manufacturing Systems and Automation, Department of Mechanical Engineering and Aeronautics, University of Patras, Patras 265 00, Greece


    Remote welding provides new possibilities for highly productive and flexible joining of metal structures, especially in the automotive industry. This study presents an experimental investigation on the behavior of the lap welds’ geometrical characteristics with respect to the laser beam inclination. Two remote welding systems (RWSs) have been utilized: a large field RWS with a CO2 laser and a small field RWS with an Nd:YAG las...

    $25.00

  • JLA Vol:9 Iss:6 (Effect of nozzle orientation on the gas dynamics of inert-gas laser cutting of mild steel)


    Authors:
    Aaron D. Brandt
    Gary S. Settles
    Gas Dynamics Laboratory, Mechanical Engineering Department, Penn State University, University Park, PA 16802, U.S.A.


    This investigation applies sonic and supersonic coaxial and off&hyphen;axis nozzles to the cutting of mild steel sheet of 1–4 mm thickness. A 1.5 kW CW CO2 laser is used with nitrogen as the assist gas. Sonic coaxial cutting is compared to that of off&hyphen;axis nozzles, which vary in orientation from 20–60° behind the laser axis and in exit Mach number from 1 to 2.4. Results show a 50&percnt; increase in maximum cutting speed at approximately a 40° off&hyphen;axis nozzle angle. In com...

    $25.00

  • JLA Vol:3 Iss:3 (Treating Birthmarks With Diabetes)


    Authors:
    Myron L. Wolbarsht
    Psychology Department, Duke University


    $25.00

  • JLA Vol:14 Iss:2 (Development of simulated pigmented lesions in an optical skin-tissue phantom: Experimental measurements in the visible and near infrared)


    Authors:
    Manuela Lualdi
    Ambrogio Colombo
    Alberto Mari
    Stefano Tomatis
    Renato Marchesini
    Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy


    Realistic, pigmented skin simulants (“phantoms”) can be useful in optimizing dermal laser procedures and for laser surgical training. Diffuse reflectance of skin pigmented lesions depends on the amount and distribution of the absorbing/diffusing chromophores, mainly hemoglobin and melanin, embedded in the skin layers. The reason why diffuse reflectance of benign melanocytic lesions is different from that of melanoma is still unclear. In an attempt...

    $25.00

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