JLA Vol:20 Iss:4 (Laser cutting of 2024-T3 aeronautic aluminum alloy)

Authors:
A. Riveiro
F. Quintero
F. Lusquin˜os
J. Pou
M. Pe´rez-Amor
Departamento de Fi´sica Aplicada, Universidade de Vigo, ETS Ingenieros Industriales, Vigo, 36310, Spain

Since the beginning of the aeronautic industry, aluminum alloys have played a crucial role in its development. Nowadays, different aluminum alloy families are the base material of many pieces of aerospace vehicles. In this work, a novel approach to process aluminum alloys is explored. The authors efforts are aimed to cut 2024-T3 plates by a CO₂ laser. They used a novel laser cutting head assisted by a gas jet working in supersonic regim...

JLA Vol:8 Iss:3 (Laser Hardened Materials Evaluation Laboratory (LHMEL))

Authors:
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...

JLA Vol:2 Iss:2 (Binary Phase Gratings for Materials Processing)

Authors:
Paul J. Patt
Array

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...

JLA Vol:14 Iss:4 (Visible and invisible laser radiation—problems in laser safety terminology)

Authors:
David H. Sliney
U.S. Army Center for Health Promotion and Preventive Medicine, Aberdeen Proving Grounds, Maryland 21010

David J. Lund
U.S. Army Medical Research Detachment, Brooks Air Force Base, Texas 78235

Wesley J. Marshall
U.S. Army Center for Health Promotion and Prevention Medicine, Aberdeen Proving Grounds, Maryland 21010

The spectral band between 400 and 700 nm is termed “visible” in laser safety standards, this is not the full extent of the visible spectrum. Light, or visible radiation, is that which is perceived by the human eye, and the spectral bandwidth for vision is really larger, extending into what some r...

JLA Vol:19 Iss:1 (Three-dimensional numerical approach for geometrical prediction of multilayer laser solid freeform fabrication process)

Authors:
Masoud Alimardani
Ehsan Toyserkani
Jan P. Huissoon
Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada

This article presents the development of a three-dimensional numerical method for predicting transient geometrical and thermal characteristics of multilayer laser solid freeform fabrication as a function of process parameters and material properties. In the proposed method, the thermal domain is numerically obtained, assuming the interaction between the laser beam and powder stream is to be decoupled. Once the melt pool boundary is obtained, the physical domain is discretized in a cross-se...

JLA Vol:25 Iss:5 (Heat transfer and fluid flow in additive manufacturing)

Authors:
A. Raghavan
H. L. Wei
T. A. Palmer
T. DebRoy
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802

In laser-based direct energy deposition additive manufacturing, process control can be achieved through a closed loop control system in which thermal sensing of the melt pool surface is used to adjust laser processing parameters to maintain a constant surface geometry. Although this process control technique takes advantage of important in-process information, the conclusions drawn about the final solidification structure and mechanical properties of the deposited material are li...

JLA Vol:24 Iss:4 (Laser-assisted nanofabrication of carbon nanostructures)

Authors:
Yun Shen Zhou
Wei Xiong
Jongbok Park
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511, USA

Min Qian
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588-0511, USA and Department of Physics, East China Normal University, Shanghai 200062, People’s Republic of China

Masoud Mahjouri-Samani
Yang Gao
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511, USA

Lan Jiang
Department of Mechanical and Automation Engineering, Beijing Institute of Technology, Bei...

JLA Vol:5 Iss:1 (Heat Flow in Laser Die Blank Welding)

Authors:
Y.‐S. Yang
C. R. Hsu
C. E. Albright
Y. Kuroda

Laser welded die blanks are finding increased usage in many industrial applications. This investigation was undertaken to establish a simplified means of calculating thermal cycles experienced in the fusion and heat affected zones on laser welds typically used in die blank welding. A planar solution domain perpendicular to the direction of travel was selected to simplify the finite element calculations. The resulting calculation technique provided reasonably accurate prediction of the thermal cycles measured by Moon and Metzbower, and the size of fusion zones and heat affected zones o...

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 16056

The 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...

JLA Vol:21 Iss:4 (Contributions of Charles Townes’ research to nonlinear optics)

Authors:
Elsa Garmire
Thayer School of Engineering, Dartmouth College, Hanover, New Hampshire 03755, USA

Nonlinear optics was profoundly influenced by early work of Charles Townes and his group at Massachusetts Institute of Technology from 1961 to 1967. His foundational contribution was the realization that coherent molecular oscillations resulted from stimulated Raman scattering, leading to the introduction of stimulated Brillouin scattering. Self-trapping of light beams and self-steeping of light pulses in nonlinear materials were two other important innovations. Some applications today of these early ideas are outlined.