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Search Publications by: Brian Simonds (Fed)

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Displaying 26 - 50 of 76

In Situ Monitoring of Cu/Al Laser Welding using Laser Induced Fluorescence

September 10, 2020
Author(s)
Brian Simonds, Tran N. Tran, Paul A. Williams
We investigate laser spot welding of 200 µm thick Cu and Al foils using laser-induced fluorescence (LIF). The key to strong Cu/Al welds is limited intermetallic compound formation through controlled molten metal interaction time. For laser lap welds, Cu in

Simultaneous High-speed X-ray Transmission Imaging and Absolute Dynamic Absorptance Measurements during High-power Laser-metal Processing

September 10, 2020
Author(s)
Brian Simonds, Jack R. Tanner, Alexandra B. Artusio-Glimpse, Paul A. Williams, Niranjan Parab, Cang Zhao, Tao Sun
During high-power laser metal processing, the absorbed light is intimately related to the molten metal cavity shape. For the first time, we directly and simultaneously observe this relationship by implementing state-of-the-art techniques of high-speed x

Measurement of thermophysical properties of NIST SRM 1155a (Cr18-Ni12-Mo2)

December 9, 2019
Author(s)
Peter Pichler, Brian Simonds, Jeffrey W. Sowards, Gernot Pottlacher
SRM 1155a is an AISI 316 stainless steel (Cr18-Ni12-Mo2) and Standard Reference Material (SRM) intended for use with test methods for elemental analysis. At the National Institute of Standards and Technology (NIST) in Boulder, Colorado dynamic absorptance

Time-Resolved Absorptance and Melt Pool Dynamics during Intense Laser Irradiation of a Metal

October 25, 2018
Author(s)
Brian J. Simonds, Jeffrey W. Sowards, Joshua A. Hadler, Erik A. Pfeif, Boris Wilthan, Jack R. Tanner, Paul A. Williams, John H. Lehman
Laser welding is a complex, dynamic process by which focused, high-intensity laser light is used to join two metallic surfaces and is being increasing deployed in a variety of industrial applications. Determining the time-dependent absorptance of the laser

Dynamic and absolute measurements of laser coupling efficiency during laser spot welds

September 3, 2018
Author(s)
Brian J. Simonds, Jeffrey W. Sowards, Joshua A. Hadler, Erik A. Pfeif, Boris Wilthan, Jack R. Tanner, Chandler Harris, Paul A. Williams
Laser absorptance (coupling efficiency) changes rapidly during laser metal processing due to temperature and multiple phase changes. We find that there is limited literature data available, but this property is vital for accurate process simulations, as

Reduction of Short Wavelength Reflectance of Multi-wall Vertically Aligned Carbon Nanotubes Through UV Laser Irradiation

May 29, 2018
Author(s)
Michelle S. Stephens, Brian J. Simonds, Christopher S. Yung, Davis R. Conklin, David J. Livigni, Alberto R. Oliva, John H. Lehman
Multi-wall carbon nanotube coatings are used as broadband, low-reflectance absorbers for bolometric applications, blackbody radiators, and for stray light control. Irradiation of single wall carbon nanotubes with UV laser light has been shown to remove

Optical Measurements of Dynamic Absorptance during High-power Laser Spot Welding

May 7, 2018
Author(s)
Brian Simonds, Jeffrey W. Sowards, Joshua A. Hadler, Boris Wilthan, Erik A. Pfeif, Jack R. Tanner, Chandler Harris, Paul A. Williams, John Lehman
We present precision measurements of the time-dependent absorptance during a 10 ms fiber-laser spot weld on 316L stainless steel. From these, the precise time and energy at which a keyhole is formed can be determined.

On-site multi-kilowatt laser power meter calibration using radiation pressure

December 1, 2017
Author(s)
Paul A. Williams, Joshua A. Hadler, Brian J. Simonds, John H. Lehman
We have demonstrated the calibration of a thermal power meter against a radiation-pressure power meter in the range of 20 kW in a manufacturing test environment. The results were compared to a traditional calorimeter-based laboratory calibration undertaken