• JLA Vol:17 Iss:1 (Thermodynamics and laser material processing)


    Authors:
    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...

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  • JLA Vol:17 Iss:2 (Autogenous laser keyhole welding of aluminum alloy 2024)


    Authors:
    B. Hu
    Netherlands Institute for Metals Research, Rotterdamseweg 137, 2628 AL Delft, The Netherlands

    I. M. Richardson
    Delft University of Technology, Rotterdamseweg 137, 2628 AL Delft, The Netherlands


    Aluminum alloy (AA) 2024 is one of the heat treatable aluminum alloys regarded as difficult to fusion weld using autogenous techniques. In this study the weldability of AA 2024 sheet with autogenous laser keyhole welding was examined as part of a systematic study on the welding parameters in order to obtain the optimal welding conditions. A high-speed video camera was employed to capture the keyhole dynamics. Results from the high-speed video show that a rou...

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  • JLA Vol:17 Iss:2 (Experimental investigation on the weldability and forming behavior of aluminum alloy tailor-welded blanks)


    Authors:
    C. H. Cheng
    L. C. Chan
    Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

    C. L. Chow
    Department of Mechanical Engineering, University of Michigan-Dearborn, Dearborn, Michigan 48128

    T. C. Lee
    Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China


    Aluminum alloy tailor-welded blanks (TWBs) have developed rapidly due to increasing interest and market pressure [J. M. Story, S. Heinemann, and S. Naegeler, Light Metal Age 56, 40–47 (1998). R. W. Davies, H. E. Oliver, M. T. ...

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  • JLA Vol:17 Iss:2 (Feedback control effects on dimensions and defects of H13 tool steel by direct metal deposition process)


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


    As a promising and novel manufacturing technology, laser aided direct metal deposition (DMD) process produces near-net-shape functional metal parts directly from the computer aided design (CAD) model. In-process feedback control has been recognized as a critical element to ensure the dimensional accuracy as well as near-net-shape production. Furthermore, process parameters should be delicately controlled to produce defect-free parts with superior mechanical properties. A closed loop real-time optical height control system...

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  • JLA Vol:17 Iss:2 (Improved adsorption of human plasma fibronectin on magnesia partially stabilized zirconia (MgO&ndash;PSZ) bioceramic resulting from CO<sub>2</sub> laser irradiation)


    Authors:
    L. Hao
    J. Lawrence
    Manufacturing Engineering Division, School of Mechanical & Production Engineering, Nanyang Technological University (NTU), Singapore 639798


    The adsorption of proteins onto a biomaterial surface from the surrounding fluid phase is rapid, with the surface properties of the biomaterial determining the type, amount, and conformation of the adsorbed proteins. Magnesia partially stabilized zirconia (MgO–PSZ), a bioinert ceramic used at the high-load bearing sites, does not naturally form a direct bond with bone. It is believed that a favorable adsorption of the fibronectin could promote cell adhesion and subsequently the bonding between the...

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  • JLA Vol:17 Iss:2 (Modeling of laser deposition and repair process)


    Authors:
    Lijun Han
    Kaushik M. Phatak
    F. W. Liou
    Department of Mechanical and Aerospace Engineering, University of Missouri-Rolla, Rolla, Missouri 65409-1350


    Laser aided deposition is a material additive based manufacturing process via metallurgically bonding the deposited material to the substrate. Due to its capability to bond various materials together, it becomes an attractive technology for part repair in small scale. However, the details of the process remain an active area for research because of the complicated interactions involved. In this study, a mathematical model was established to investigate thermal and mass transportation phenomena, which incl...

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  • JLA Vol:17 Iss:2 (Numerical simulation of femtosecond laser interaction with silicon)


    Authors:
    Hyungson Ki
    Mechanical Engineering Department, Michigan State University, East Lansing, Michigan 48824-1226

    Jyoti Mazumder
    Center for Laser Aided Intelligent Manufacturing, University of Michigan, Ann Arbor, Michigan 48109-2125


    A numerical model for simulating femtosecond laser interaction with silicon is presented. This model simulates laser beam propagation by directly solving Maxwell’s equations using the finite-difference time-domain method, so that complete electromagnetic nature of a laser beam is simulated accurately. Accurate computation of laser beam passage ensures realistic heat generation pattern in the target material. The two-temperat...

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  • JLA Vol:17 Iss:2 (Property enhancement of diffusion borided layers by laser treatment)


    Authors:
    S. M. Shariff
    Vipin Jain
    G. Sundararajan
    S. V. Joshi
    International Advanced Research Centre for Powder Metallurgy & New Materials, Balapur P.O., Hyderabad-500005, India


    Tribological properties such as abrasion and erosion resistance of boride coatings on steels have been proven to be outstanding when compared with conventional hardening techniques, e.g., carburizing and nitriding. Pack boriding is a relatively simple and economical technique among all the methods available for boriding. A single phase Fe2B layer is desirable in the boride coating for its superior performance and this can be achieved in several ways. Howeve...

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  • JLA Vol:17 Iss:3 (Determination of true stress-strain curve for the weldment of aluminum laser-welded blanks)


    Authors:
    C. H. Cheng
    L. C. Chan
    C. Y. Tang
    Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

    C. L. Chow
    Department of Mechanical Engineering, University of Michigan-Dearborn, Dearborn, Michigan 48128


    In the automotive industry, the weld quality of aluminum laser-welded blanks (LWBs) is generally assessed by a conventional transverse tensile test. The engineering stress-strain curve, together with other tensile properties (e.g., yield strength, tensile strength, and total elongation) of the monolithic LWBs, can then be obtained by this test. However, LWBs should be ...

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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 ...

    $25.00

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