JLA Vol:17 Iss:2 (Improved adsorption of human plasma fibronectin on magnesia partially stabilized zirconia (MgO–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 639798The 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 65409-1350Laser 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 48109-2125A 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, IndiaTribological 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 48128In 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— 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, FranceLaser 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 ...
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JLA Vol:17 Iss:3 (High-speed scanning laser-induced breakdown spectroscopy at 1000 Hz with single pulse evaluation for the detection of inclusions in steel)
Authors:
Holger Bette
Reinhard Noll
Fraunhofer-Institut fu¨r Lasertechnik (ILT), Steinbachstr. 15, 52074 Aachen, Germany
Gregor Mu¨ller
Hans-Werner Jansen
C¸etin Nazikkol
Horst Mittelsta¨dt
ThyssenKrupp Stahl AG, Kaiser-Wilhelm-Str. 100, 47166 Duisburg, GermanySpatially resolved information about the distribution and chemical composition of inclusions in steel are gained by scanning methods, such as scanning electron microscopy with energy dispersive X-ray spectroscopy, electron probe microanalysis or capillary-X-ray flourescence. Scanning laser-induced breakdown spectroscopy (LIBS) offers dis...
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JLA Vol:17 Iss:3 (Investigation of the irradiance-dependent spectral transmittance of laser filters in the nanosecond- and femtosecond-pulse regime in the wavelength range between 700 and 800 nm)
Authors:
A. Schirmacher
E. Sutter
O. Werhahn
U. Siegner
A. Nevejina-Sturhan
Physikalisch-Technische Bundesanstalt, Braunschweig, Bundesallee 100, 38116 Braunschweig, GermanyInduced transmittance is observed with polycarbonate laser filters when they are irradiated by laser pulses with a width of 200 fs. These results are compared with measurements in the nanosecond time domain. Calculations by a simple absorption model show, that single photon absorption is dominating the light-matter interaction at the pulse widths used in this study, at least at radiant exposure levels at which the filter material is not damaged. The use of eyewea...
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JLA Vol:17 Iss:3 (Laser beam analysis in direct metal deposition process)
Authors:
Huan Qi
Jyoti Mazumder
Center for Laser Aided Intelligent Manufacturing, Department of Mechanical Engineering, The University of Michigan, Ann Arbor, Michigan 48109
Larry Green
Spiricon, Inc., Logan, Utah 84341
Gary Herrit
II-VI, Inc., Saxonburg, Pennsylvania 16056The quality of a laser beam profile and its stability play fundamental roles in laser material processing. Beam reflections may dramatically affect the beam quality under certain material processing conditions. In this study, experiments were carried out to examine the variations of the continuous wave CO2 laser beam profile during the direct metal...
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JLA Vol:17 Iss:3 (Laser welding of the synchronizer stop ring and the rear gear in a manual transaxle)
Authors:
G. Casalino
Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, Bari, ItalyThe focused laser beam is one of the highest power density sources available to industry today. When the “keyhole mode” is used for welding the result is characterized by a parallel-sided fusion zone, narrow width, and deep penetration. Therefore, a higher value of the joining efficiency (i.e., the reciprocal of the specific welding energy) is obtained and less energy is necessary for heating which generates a large heat affected zone and low mechanical distortion. This article focuses on the application of the CO2 seam laser welding of the stop ring of the s...
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