JLA Vol:17 Iss:1 (Excimer laser ablation of glass-based arrayed microstructures for biomedical, mechanical, and optical applications)
Authors:
Ying-Tung Chen
Department of Mechanical Engineering, Chung Cheng Institute of Technology, Tashi, Taiwan 33508, Republic of China
Kung-Jeng Ma
Department of Mechanical Engineering, Chung Hua University, Hsinchu, Taiwan 30067, Republic of China
Jack G. Zhou
Department of Mechanical Engineering, Drexel University, Philadelphia, Pennsylvania 19104
Ampere A. Tseng
Department of Mechanical and Aerospace Engineering, Center for Solid State Electronics Research, Arizona State University, Tempe, Arizona 85287-6106An excimer laser has been used for ablation of glass-based substrates for making arrayed microstructures. T...
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JLA Vol:17 Iss:1 (Fracture control of unsupported ceramics during laser machining using a simultaneous prescore)
Authors:
A. E. Segall
G. Cai
R. Akarapu
A. Romasco
Department of Engineering Science and Mechanics, The Pennsylvania State University, University Park, Pennsylvania 16802
B. Q. Li
Department of Mechanical and Materials Engineering, Washington State University, Pullman, Washington 99164While lasers offer many advantages when machining ceramics, costly premature fractures and related damage is the tradeoff often faced by manufacturers. This tradeoff is especially apparent for higher-speed machining of complex shapes where traditional “nail-bed” supports are not always practical. To help overcome these problems, re...
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JLA Vol:17 Iss:1 (In-process monitoring and adaptive control for stable production of sound welds in laser microspot lap welding of aluminum alloy)
Authors:
Yousuke Kawahito
Seiji Katayama
Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, JapanA new procedure of in-process monitoring and adaptive control has been developed for laser microspot lap welding of A3003 aluminum alloy sheets of 0.1 and 1 mm in thickness. The objective is to consistently produce sound laser partial-penetration lap-joint welds. It was revealed that the reflected laser beam and the radiated heat from the welding area were effective as in-process monitoring signals in detecting melting, keyhole generation, and through-hole formation in the upper sheet during laser irradiation. Laser pulse...
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JLA Vol:17 Iss:1 (Microstructural characterization of dissimilar laser weld between austenitic and ferritic stainless steels)
Authors:
Rakesh Kaul
P. Ganesh
A. K. Nath
Industrial CO2 Laser Section, Centre for Advanced Technology, P. O. CAT, Indore 452 013, IndiaThe present work involved microstructural characterization of thin sheet dissimilar laser welds between type 304 austenitic stainless steel and stabilized 17% Cr ferritic stainless steel and their comparison with welds produced by autogenous gas tungsten arc welding (GTAW). Low heat input of laser welding (LW) effectively reduced the size of fusion zone (FZ) and heat affected zone (HAZ). LW with focused laser beam (LB), preferentially displaced towards austenitic stainless steel (ASS), produced FZ with uniform and highly ref...
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JLA Vol:17 Iss:1 (Review of laser hybrid welding)
Authors:
Claus Bagger
Flemming O. Olsen
IPU, Institute for Product Development, Technical University of Denmark, Building 425, DK-2800-Lyngby, DenmarkIn this article, an overview of the hybrid welding process is given. After a short historic overview, a review of the fundamental phenomenon taking place when a laser (CO2 or Nd:YAG) interacts in the same molten pool as a more conventional source of energy, e.g. tungsten in-active gas, plasma, or metal inactive gas/metal active gas. This is followed by reports of how the many process parameters governing the hybrid welding process can be set and how the choice of secondary energy source, shielding gas, etc. can a...
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JLA Vol:17 Iss:1 (The role of electron–phonon coupling in ultrafast laser heating)
Authors:
J. K. Chen
W. P. Latham
J. E. Beraun
Laser Effects Research Branch, Directed Energy Directorate, Air Force Research Laboratory, Kirtland AFB, New Mexico 87117Most of the ultrafast laser heating analysis to date has been accomplished with a constant electron–phonon coupling factor (G). Due to the significant changes in the electron and lattice temperature caused by high-power laser heating, G could be temperature dependent. In this article a phenomenological temperature-dependent G is introduced to simulate ultrafast laser heating in metals. The electron temperature and the ablation depth computed with the temperature-dependent G compare well w...
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JLA Vol:17 Iss:1 (Thermodynamics and laser material processing)
Authors:
W. W. Duley
Physics Department, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1In 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 NetherlandsAluminum 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, ChinaAluminum 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 65409-1060As 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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