Publications

Displaying 26 - 50 of 104

Characteristics and Mechanisms of Hydrogen-Induced Quasi-Cleavage Fracture of Lath Martensitic Steel

January 10, 2021

Author(s)

Lawrence Cho, Peter E. Bradley, Damian S. Lauria, May L. Martin, Matthew J. Connolly, Jake Benzing, Eun Jung Seo, Kip O. Findley, John G. Speer, Andrew J. Slifka

This study presents an in-depth characterization of the microstructures, crystallographic orientations, and dislocation characteristics beneath the hydrogen-induced quasi-cleavage features of an as-quenched, lath martensitic (') 22MnB5 steel. The fracture

Elastic-plastic properties of mesoscale electrodeposited LIGA nickel alloy films: microscopy and mechanics

November 22, 2020

Author(s)

Li-Anne Liew, David T. Read, May Martin, Frank W. DelRio, Peter E. Bradley, Nicholas Barbosa, Todd R. Christenson, John T. Geaney

The elastic-plastic properties of mesoscale electrodeposited LIGA Ni alloy specimens are investigated as a function of specimen size, strain rate, and material composition. Two material compositions are studied: a high-strength fine-grained Ni-Fe alloy and

A new method for heat transfer coefficient measurements of single-phase fluids during laminar flow in microchannels

May 22, 2020

Author(s)

Seungwhan Baek, Ray Radebaugh, Peter Bradley

The measurement of heat transfer coefficients in microchannels is complicated due to the small sizes involved. Moreover, a heat transfer mechanism which is not usually considered, the axial conduction effect in the channel wall, must also be evaluated in

Modelling the test methods used to determine material compatibility for hydrogen pressure vessel service

October 16, 2019

Author(s)

Christopher P. Looney, Matthew J. Connolly, Peter E. Bradley, Andrew J. Slifka, Robert L. Amaro

Vessels used to transport pressurized gasses via truck must be approved for service by the U.S. Department of Transportation. Many of the most common, relatively small volume, pressure vessels in service are designated as DOT 3AA cylinders. The

HEXRD Measurement of Strain and Dislocation Density ahead of Crack Tips Grown in Hydrogen

September 13, 2019

Author(s)

Matthew J. Connolly, May L. Martin, Peter E. Bradley, Damian S. Lauria, Andrew J. Slifka, Jun Sang Park, Robert Amaro

The deformation fields near fatigue crack tips grown in hydrogen and in air were measured using high-energy x-ray diffraction. A larger magnitude of elastic strain was observed in the hydrogen case compared to the air case. The magnitude of elastic strain

Unification of hydrogen-enhanced damage understanding through Strain-Life Experiments and Modeling

June 20, 2019

Author(s)

May L. Martin, Christopher P. Looney, Peter E. Bradley, Damian S. Lauria, Robert L. Amaro, Andrew J. Slifka

Strain-life testing of a 4130 pressure vessel steel was conducted in hydrogen gas through the careful adaptation of an existing hydrogen-gas mechanical testing apparatus. The strain-life mechanical results reveal that hydrogen has a significant effect on

Heat transfer coefficient measurement of LN2 and GN2 in a microchannel at low Reynolds flow.

July 30, 2018

Author(s)

Seungwhan Baek, Peter E. Bradley, Ray Radebaugh

The heat transfer coefficients of single-phase fluids in the laminar flow regime have been studied for decades. However, inconsistent results are found in the literature. The common finding is that the Nusselt number is dependent on the Reynolds number in

Demonstration of a Chamber for Strain Mapping of Steel Specimens Under Mechanical Load in a Hydrogen Environment by Synchrotron Radiation

June 4, 2018

Author(s)

Matthew J. Connolly, Peter E. Bradley, Damian S. Lauria, Andrew J. Slifka, Elizabeth S. Drexler

We present a demonstration of a chamber for diffraction measurements of lattice strain for specimens in hydrogen gas under mechanical load. The chamber is suitable for static and cyclic mechanical loading. Synchrotron x-ray radiographs of a fatigue crack

In Situ Neutron Transmission Bragg Edge and Synchrotron X-Ray Measurement of Strain Fields Near Fatigue Cracks Grown in Hydrogen

April 18, 2018

Author(s)

Matthew J. Connolly, Peter E. Bradley, Damian S. Lauria, Andrew J. Slifka, Elizabeth S. Drexler

The embrittlement and enhanced fatigue crack growth rate of metals in the presence of hydrogen is a long-standing problem. In an effort to determine the dominate damage mechanism behind hydrogen assisted fatigue crack growth, we performed High-Energy X-ray

In Situ Neutron Transmission Bragg Edge Measurements of Strain Fields Near Fatigue Cracks Grown in Air and in Hydrogen

August 14, 2017

Author(s)

Matthew Connolly, Peter Bradley, Andrew Slifka, Elizabeth S. Drexler

In situ transmission Bragg edge measurements of the strain field were performed near cracks grown in air and in hydrogen. Through the use of a novel test chamber which is capable of pressurization with hydrogen gas, and amenable to neutron-scattering

Chamber for Mechanical Testing in H2 with Observation by Neutron Scattering

June 1, 2017

Author(s)

Matthew J. Connolly, Peter E. Bradley, Andrew J. Slifka, Elizabeth S. Drexler

A gas-pressure chamber has been designed, constructed, and tested at a moderate pressure (3.4 MPa, 500 psi) and has the capability of mechanical loading of steel specimens for neutron scattering measurements. The chamber will allow a variety of in situ

Design and Analysis of a 150 K Cascade Joule-Thomson Microcooler

June 9, 2014

Author(s)

Ray Radebaugh, Peter E. Bradley, Collin J. Coolidge, Ryan J. Lewis, Y.C. Lee

Lightweight and compact microcoolers are needed for advanced, hand-held infrared systems. A temperature of 150 K is adequate for high sensitivity with some of the latest IR detectors, which simplifies the cooling requirements compared to 80 K detectors

Performance Analysis of an Integrated Micro Cryogenic Cooler and Miniature Compressor for Cooling to 200 K

June 24, 2013

Author(s)

Ryan J. Lewis, Mu Hong Lin, Yunda Wang, Jill Cooper, Peter E. Bradley, Ray Radebaugh, Marcia L. Huber, Yung-Cheng Lee

Joule-Thomson (J-T) based micro cryogenic coolers (MCCs) are attractive because they can provide the cryogenic temperatures needed for small electronic devices while having a low cost and small volumetric footprint. A compressor is a major part of a

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