U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by:

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 51 - 66 of 66

Size-Strain Line-Broadening Analysis of the Ceria Round-Robin Sample

December 1, 2004
Author(s)
Davor Balzar, N Audebrand, M R. Daymond, A Fitch, A Hewat, J I. Langford, A Le Bail, D Louer, P Masson, Christopher N. McCowan, N Popa, P W. Stephens, B H. Toby
We report the results of a line-broadening study on a ceria sample prepared for a size-strain round robin. The sample was prepared from a recursor hydrated ceria by heating in a silica crucible at 650 C for 45 hours. Another ceria sample wasprepared to

Comparison of Strength Properties of Normotensive and Hypertensive Rat Pulmonary Arteries

October 1, 2004
Author(s)
Elizabeth S. Drexler, Christopher N. McCowan, J Wright, Andrew J. Slifka, Dunbar Ivy, Robin Shandas
A series of tests were conducted to quantify the difference in the mechanical properties of normo-and hypertensive pulmonary arteries. A bubble-test design was emplpoyed to measure the biaxial properties of a segment of artery. The test results compare the

Constitutive Models for a Poly(e-caprolactone) Scaffold

October 1, 2004
Author(s)
Timothy P. Quinn, Tammy L. Oreskovic, Christopher N. McCowan, N Washburn
We investigate material models for a porous, polymeric scaffold used for bone. The material was made by co-extruding poly (e-caprolactone) (PCL), a biodegradable polyester, and poly(ethylene oxide)(PEO). The water soluble PEO was removed resulting in a

The Structural Steel of the World Trade Center Towers

October 1, 2004
Author(s)
Frank W. Gayle, Stephen W. Banovic, Timothy J. Foecke, Richard J. Fields, William E. Luecke, Joseph D. McColskey, Thomas A. Siewert, Christopher N. McCowan
In September 2002, the National Institute of Standards and Technology became the lead agency in an investigation of the World Trade Center (WTC) disaster of September 11, 2001. The investigation addresses many aspects of the catastrophe, from occupant

The NIST Charpy V-Notch Verification Program: Overview and Operating Procedures

September 1, 2003
Author(s)
Christopher N. McCowan, Thomas A. Siewert, D P. Vigliotti
Charpy impact testing is often specified as ,in acceptance test for structural materials, and companies performing acceptance tests are typically required to verify the performance of their impact machine periodically. The procedure for verifying the

An Experimental Method for Measuring Mechanical Properties of Rat Pulmonary Arteries Verified With Latex

June 1, 2003
Author(s)
Elizabeth S. Drexler, Andrew J. Slifka, J Wright, Christopher N. McCowan, Dudley Finch, Timothy P. Quinn, J D. McCloskey, Dunbar Ivy, Robin Shandas
A study of the biomechanics and hemodynamics of pulmonary hypertension is incomplete without including mechanical properties data comparing healthy and diseased arterial tissue. In the initial stabe of this study, Sprague-Dawley rats will be induced with

Failure Analysis of the WWVB Tower

August 1, 2002
Author(s)
Joseph D. McColskey, Christopher N. McCowan, Raymond L. Santoyo
A failure analysis was conducted on the collapse of the NIST WWVB tower. The analysis included mechanical testing, chemical analysis, and metallographic examination of the failed part. We ascertained that the underlying reason for the collapse was fatigue

The History and Importance of Impact Testing

May 1, 2002
Author(s)
Thomas A. Siewert, M P. Manahan, Christopher N. McCowan, J M. Holt, F J. Marsh
Charpy impact testing is a low-cost and reliable test method which is commonly required by the construction codes for fracture-critical structures such as bridges and pressure vessels. yet, it took from about 1900 to 1960 for impact-test technology and

Maintaining the Accuracy of Charpy Impact Machines

May 1, 2000
Author(s)
D P. Vigliotti, Thomas A. Siewert, Christopher N. McCowan
The quality of the data developed by impact machines tends to degrade over time, due to the effects of weear and vibration that are inherent in the test. This is the reason that impact standards specify periodic direct and indirect verification tests. Each

Secondary Ferrite Number Reference Materials: Gage Calibration and Assignment of Values

February 1, 2000
Author(s)
Christopher N. McCowan, Thomas A. Siewert, D P. Vigliotti, C M. Wang
Ferrite Numbers (FN) were assigned to blocks of stainless steel that serve as secondary ferrite reference materials (RM 8480 and 8481), and these specimens were placed in our Reference Materials inventory. These reference materials are used to calibrate

Performance Verification of Impact Machines for Testing Plastics

December 1, 1999
Author(s)
Thomas A. Siewert, D P. Vigliotti, L B. Dirling, Christopher N. McCowan
Valid comparison of impact test energies reported by various organizations and over time depends on consistent performance of impact test machines. This paper investigates the influence of various specimen and test parameters on impact energies in the I J

Welding Consumable Development for a Cryogenic (4K) Application

August 1, 1999
Author(s)
S F. Kane, A L. Farland, Thomas A. Siewert, Christopher N. McCowan
This paper summarizes the development and qualification of an appropriate welding consumable for a demanding cryogenic magnet application. It begins with a review of the research conducted on cryogenic fracture toughness of wrought and welded austenitic

Metallurgical Evaluation of Prestressed Wire Failures

July 1, 1998
Author(s)
Christopher N. McCowan, Thomas A. Siewert
Prestressed concrete pipe, having an inside diameter of 6.4 m (21 ft), was used to construct a series of siphons for the Central Arizona Project.