JLA Vol:15 Iss:4 (Laser–material interaction and process sensing in underwater Nd:yttrium–aluminum–garnet laser welding)
Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China
Tarasaki R&D Center, JAPEIC, Hitachinaka, Ibaraki 312-0003, Japan
Laser–material interaction and process sensing technology for local-dry underwater Nd:yttrium–aluminum–garnet laser beam welding were studied. The optical emissions induced by laser–water interaction were detected with an infrared (IR) optical sensor and observed with a charge coupled device camera. It was found that under laser irradiation, a kind of water–vapor plasma formed immediately above the ...
JLA Vol:20 Iss:1 (Practical and theoretical investigations into inert gas cutting of 304 stainless steel using a high brightness fiber laser)
Centre for Industrial Photonics, Institute for Manufacturing, Department of Engineering, University of Cambridge, Cambridge, CB2 1RX, United Kingdom
A 2.2 kW fiber laser was used in a series of inert cutting trials on stainless steels of section thicknesses in the range of 6–10 mm. Variations in the cutting performance with changing gas pressure, focal position, and nozzle diameter were investigated. Results showed the difficulties associated in cutting with high brightness lasers, specifically in obtaining full melt eject through narr...
JLA Vol:23 Iss:4 (Evaluation of the bone repair in defects grafted with hydroxyapatite and collagen membrane combined with laser therapy in rats)
Marcelo Rodrigues da Cunha
Luanda de Abreu Figueira
Joa˜o Paulo Mardegan Issa
Ricardo Alexandre Junqueira Calzzani
Daniele Cristina do Prado Ribeiro
Mariane Silva Pettian
Bone regeneration is the result of cellular events such as osteogenesis and neovascularization. However, implantation of autogenous grafts may be necessary in cases of bone mass loss due to high impact trauma. The disadvantages of the latter approach include morbidity of the donor area. Biomaterials represent an alternative for bone restoration. The most widely used compounds are collagen or hydroxyapat...
D. H. Abbott
C. E. Albright
The most widely used shielding gases for laser welding of steels are helium and argon. Helium produces significantly more penetration than argon in penetration‐mode laser beam welding. Another gas that has been proposed as an alternative to these inert gases is carbon dioxide. The benefits of using carbon dioxide as a shielding gas for laser welding are that it costs less than helium and argon and that it provides nearly the same penetration as helium. The major drawback to its use as a shielding gas for mild steel is that it can cause porosity and other weld discontinuities. In this investigation helium and carbon dioxide were...
JLA Vol:14 Iss:1 (Physical–computational model to describe the interaction between a laser beam and a powder jet in laser surface processing)
O. O. Diniz Neto
Departamento de Engenharia de Materiais, Instituto Superior Te´cnico, 1049-001 Lisboa, Portugal
Frequently laser surface treatments use a powder jet in conjunction with the laser beam. In this study we present a physical–computational model to describe the interaction between a laser beam and a powder jet. The model can be used to calculate the spatial distribution of particle temperature and laser beam attenuation at any moment and all over the region where the laser and particle beams interact. In calculating particle temperature, the attenuation of the laser beam by the particles themselves is taken into acc...
JLA Vol:18 Iss:2 (Fabrication of titanium microchannels using laser-assisted thermochemical wet etching)
S. W. Son
M. K. Lee
K. H. Oh
S. H. Jeong
Department of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryongdong Bukgu, Gwangju, 500-712 Republic of Korea
A fabrication method of titanium microchannels of an aspect ratio up to 16 and channel width of 10–30 μm is developed using laser-assisted thermochemical wet etching. For the fabrication of deep channel, the workpiece was repeatedly etched over the same path with the control of process parameters. The cross-sectional profile of the microchannel varied between a V shape and a U shape, depending largely upon the laser beam power and etchant concentration. Bubb...
M. T. Wang
Inner Mongolia University, Hohhot 010021, China
A novel localization scheme called laser beam scan localization by combining grid and light (laser) with mobile localization policy for wireless sensor networks is designed. The scheme utilizes a moving location assistant (LA) with a laser beam, through which the deployed area is scanned. The LA sends identities to unknown nodes to obtain the locations of sensor nodes. High localization accuracy can be achieved without the aid of expensive hardware on the sensor nodes, as required by other localization systems...
R. J. Hull
M. L. Lander
Since 1976, the Laser Hardened Materials Evaluation Laboratory (LHMEL) has been characterizing material responses to laser energy in support of national defense programs and the aerospace industry. Now that capability is available to commercial industry as well. LHMEL's power levels, beam uniformity, and diagnostics capabilities make it an ideal facility for proof‐of‐concept testing or process development. Located at Wright‐Patterson Air Force Base, Ohio, LHMEL is managed by the Wright Laboratory Materials Directorate and operated by Lawrence Associates, Incorporated. The facility's advanced hardware is centered aroun...
Paul J. Patt
The feasibility of using a diffractive optical element, a phase grating, as a beam handling device for use in industrial laser material processing is examined. The binary phase grating is an efficient beam splitting device and is useful in many materials processing operations (welding, cutting, soldering, drilling) where a high degree of parallelism could significantly improve process throughput. Overall efficiency of etched quartz binary gratings agrees well with published predictions (nominal 70–90%). Copies of the grating formed in PMMA (acrylic) survived preliminary life tests (more than 1000 9‐J pulses from a commercial multimode N...
Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan
The object of this study is to investigate the solidification problem in laser cladding with the wire feeding technique. The solidification phenomenon of laser cladding was analyzed by numerical simulation and experimental visualization. Good agreement has been obtained for 304 stainless steel wires cladding on round tubes and it transpires that there were three basic modes of clad profiles: thinning, thickening, and wavering of the clad thickness at different velocity settings between the feeding wire and the substrate in laser wire cladding. ©...
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