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Search Publications by: Walter G. McDonough (Fed)

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Displaying 26 - 50 of 93

The Effect of Folding on the Mechanical Properties and Internal Structures of Fibers Used in Ballistic Applications

July 18, 2011
Author(s)
Haruki Kobayashi, Walter G. McDonough, Hae-Jeong Lee, Jae H. Kim, Amanda L. Forster, Kirk D. Rice, Gale A. Holmes
The failure of a first responder's soft body armor (SBA) composed of poly (p-phenylene benzobisoxazole) (PBO) fibers has prompted researchers to assess the long-term durability and effectiveness of current and future SBA products. Based on existing data

Statistical analysis of fiber gripping effects on Kolsky bar test

June 14, 2011
Author(s)
Jae Hyun Kim, Nathanael A. Heckert, Stefan D. Leigh, Haruki Kobayashi, Walter G. McDonough, Richard L. Rhorer, Kirk D. Rice, Gale A. Holmes
Preliminary data for testing fibers at high strain rates using the Kolsky bar test by Ming Cheng et al. 1 indicated minimal effect of strain rate on the tensile stress-strain behavior of PPTA, poly (p-phenylene terephathalamide) fibers. In a different

The Effect of Folding on the Internal Structure of Ballistic Fibers

May 26, 2011
Author(s)
Haruki Kobayashi, Walter G. McDonough, Hae-Jeong Lee, Jae H. Kim, Amanda L. Forster, Kirk D. Rice, Gale A. Holmes
In one of our previous studies, the mechanical properties of poly (p-phenylene benzobisoxazole) (PBO) fibers were degraded when the fibers were folded. When we examined poly (p-phenylene terephthalamide) (PPTA) fibers, we did not find a similar drop in

The Role of Folding in the Degradation of Ballistic Fibers

August 2, 2010
Author(s)
Gale A. Holmes, Walter G. McDonough, Jae H. Kim, Derek L. Ho
Failures of certified soft body armor led to a call to understand the underlying mechanisms of the failure. Research has indicated that the folding of ballistic fibers comprising the soft body armor may be a factor in the performance deterioration that has

Effects of fiber gripping methods on single fiber tensile test using Kolsky bar

June 10, 2010
Author(s)
Jae Hyun Kim, Richard L. Rhorer, Haruki Kobayashi, Walter G. McDonough, Gale A. Holmes
Preliminary data by Ming Cheng et al. indicate minimal impact of strain rate on the tensile stress-strain behavior of Kevlar. However, technical issues associated with specimen preparation appear to limit the number of samples and show an undesirable

A Graphical Approach for Assessing High Strength Fiber Performance

May 20, 2010
Author(s)
Walter G. McDonough, Gale A. Holmes, Amanda L. Forster, Kirk D. Rice
The design and materials used for bullet resistant body armor have evolved continuously to keep up with the threats. In this paper, a graphical approach is presented that plots the potential strain energy absorption of some common high performance fibers

High Speed Fiber Testing: The Single Fold Test

May 20, 2010
Author(s)
Haruki Kobayashi, Walter G. McDonough, Alexander J. Shapiro, Jae H. Kim, Stefan D. Leigh, Amanda L. Forster, Kirk D. Rice, Gale A. Holmes
The failure of a first responder s body armor has prompted research to assess the long-term durability and effectiveness of current and future soft body armor products. Prior work in this laboratory described a 10 % drop in tensile strength and 15 % drop

The Effect of Environmental and Mechanical Mechanisms on the Performance of Soft Body Armor

July 27, 2009
Author(s)
Gale A. Holmes, Eun S. Park, Jae Hyun Kim, Walter G. McDonough, John R. Sieber, Haruki Kobayashi, Michael A. Riley, Kirk D. Rice
The use of high performance fibers (such as, poly[(benzo-[1,2-d;5,4-d ]-benzoxazole-2,6-diyl)-1,4-phenylene]1 (PBO), ultra-high molecular weight polyethylene2 (UHMWPE), and poly(p-phenylene terephthalamide)3 (PPTA)) in soft body armor (SBA) is well

Coordinated Fracture and Failure Initiation in Microcomposites

October 16, 2008
Author(s)
Gale A. Holmes, Jae H. Kim, Chang K. Moon, Walter G. McDonough
In this paper, the failure behavior of glass fiber microcomposites is investigated. E-glass fibers treated with an epoxy compatible sizing were embedded in a diglycidyl ether of bisphenol-A (DGEBA) resin cured with meta-phenylenediamine (m-PDA). Even

The Role of Folding in the Degradation of Ballistic Fibers

May 19, 2008
Author(s)
Walter G. McDonough, Gale A. Holmes, Jae Hyun Kim, Derek L. Ho
Research has indicated that the folding of ballistic fibers comprising soft body armor may be a factor in the performance deterioration that has been observed. To quantify the impact of this failure mechanism on body armor performance, an apparatus was

The Modified-Single Fiber Test: A Methodology for Monitoring Ballistic Performance

January 18, 2008
Author(s)
Jae Hyun Kim, Walter G. McDonough, William R. Blair, Gale A. Holmes
In an effort to develop a minimally invasive testing methodology for monitoring the in-service performance of soft body armor, the ASTM D3379-75 standard was modified by measuring the fiber diameter at 5 equally spaced locations along a 6 cm gauge length

A Device for Mechanically Folding Yarns and Woven Fabrics of Ballistic Fibers

January 7, 2008
Author(s)
Walter G. McDonough, Jae Hyun Kim, Nolan J. Brandenburg, William R. Blair, Gale A. Holmes
Abstract (2000 characters maximum - spell out acronyms the first time)An apparatus was designed and built that attaches to servo-hydraulic machines that typically perform material fatigue testing. The device was designed to systematically fold woven fabric

E-Glass/DGEBA/m-PDA Single Fiber Composites: Interface Debonding During Fiber Fracture

October 1, 2007
Author(s)
Gale A. Holmes, R C. Peterson, Donald L. Hunston, Walter G. McDonough
In this paper, we examine the regions of debonding between the fibers and the matrix surrounding fiber breaks formed during single-fiber fragmentation tests. The materials used were E-glass fibers embedded in a matrix of diglycidyl ether of bisphenol-A

An Apparatus For Folding Yarns And Woven Fabrics Of Ballistic Fibers

June 4, 2007
Author(s)
Walter G. McDonough, Jae Hyun Kim, Nolan J. Brandenburg, William R. Blair, Gale A. Holmes
Folding of ballistic fibers comprising soft body armor may be a factor in the performance deterioration that has been observed in used soft body armor. To quantify the impact of this mechanism, an apparatus was designed and built to simulate the folding

Chemistry of Silanes Interfaces in Dental Polymers and Composites

September 1, 2005
Author(s)
Joseph M. Antonucci, Sabine H. Dickens, Bruce O. Fowler, Hockin D. Xu, Walter G. McDonough
The performance and service life of glassor ceramic-filled polymeric composites depend on the nature of their resin, filler and interfacial phases as well as the efficacy of the polymerization process. The synergy that exists between the organic polymer