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Search Publications by: Joy Dunkers (Fed)

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Displaying 151 - 175 of 197

Permeability Prediction From Non-Destructive Imaging of Composite Microstructure

May 1, 2001
Author(s)
Joy Dunkers, Frederick R. Phelan Jr., Kathleen M. Flynn, D P. Sanders, Richard~undefined~undefined~undefined~undefined~undefined Parnas
In this work, binary images of the microstructure of a unidirectional E-glass/epoxy composite were generated from the low contrast OCT data through image de-noising, contrast enhancement and feature recognition. The resulting data were input to a lattice

Studying the Buried Interfacial Region With an Immobilized Fluorescence Probe

March 1, 2001
Author(s)
Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, J H. VanZanten, Joy Dunkers, Richard~undefined~undefined~undefined~undefined~undefined Parnas
The properties of a buried epoxy / glass interfacial region were studied by covalently grafting a fluorescent probe to the glass surface. A dimethyl-amino-nitrostilbene (DMANS) fluorophore was tetherred to a triethoxy silane-coupling agent, generating a

Fiber Optic Flow and Cure Sensing for Liquid Composite Molding

February 1, 2001
Author(s)
Joy P. Dunkers, Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, S R. Kueh, J H. VanZanten, S G. Advani, Richard~undefined~undefined~undefined~undefined~undefined Parnas
The Polymer Composites group at the National Institute of Standards and Technology has efforts in both on-line flow and cure sensing for liquid composite molding. For our flow program, a novel fiber optic real time sensor system has been developed that can

The Application of Optical Coherence Tomography to Problems in Polymer Matrix Composites

January 1, 2001
Author(s)
Joy Dunkers, Frederick R. Phelan Jr., D P. Sanders, M J. Everett, William H. Green, Donald L. Hunston, Richard~undefined~undefined~undefined~undefined~undefined Parnas
The Composites Group at the National Institute of Standards and Technology has found optical coherence tomography (OCT) to be a powerful tool for non-destructive characterization of polymer matrix composites. Composites often exhibit superior properties to

Interfacial Response of a Fluorescent Dye Grafted to Glass

October 1, 2000
Author(s)
Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, J H. VanZanten, Joy Dunkers, Richard~undefined~undefined~undefined~undefined~undefined Parnas
The Quality of the fiber/resin interphase region is critical to the final mechanical properties of a composite. By grafting a fluorescent dye to a glass microscope cover slip, a model interphase region can be directly studied. A blue shift and increase in

Imaging of Composite Defects and Damage Using Optical Coherence Tomography

May 1, 2000
Author(s)
Joy Dunkers, M J. Everett, D P. Sanders, Donald L. Hunston
The Composites Group at the National Institute of Standards and Technology has found optical coherence tomography (OCT) to be a powerful tool for non-destructive characterization of polymer matrix composites. Composites can be made more cost competitive by

Long-Period Gratings as Flow Sensors for Liquid-Composite Molding

May 1, 2000
Author(s)
S R. Kueh, Richard~undefined~undefined~undefined~undefined~undefined Parnas, Joy Dunkers, S G. Advanti, P S. Furrows, M E. Jones, T A. Bailey
One of the most important issues in liquid composite molding (LCM) is the complete saturation of the preform by the resin to eliminate voids or dry spots in the structure which could later adversely affect the structural integrity of the part. While there

Interfacial Response of a Fluorescent Dye Grafted to Glass

April 12, 2000
Author(s)
Joy P. Dunkers, Jospeh L. Lenahrt, J Van Zanten, Richard~undefined~undefined~undefined~undefined~undefined Parnas
The properties of an epoxy/glass interfacial region are studied by covalently grafting a fluorescent probe to the glass surface. A dimethylaminonitrostilbene fluorophore is tethered to a triethoxysilane-coupling agent, generating a fluorescently labeled

Imaging of Impact Damage in Composites Using Optical Coherence Tomography

February 1, 2000
Author(s)
Joy Dunkers, D P. Sanders, Donald L. Hunston, M J. Everett
Resistance to impact damage is extremely important for most composites. Such damage can initiate delamination, one of the most common failure modes in composites.. Because this is such an important failure mode, many studies have tried to develop matrix

A Practical Fiber Optic Sensor to Monitor Resin Cure and Interphase Formation

January 1, 2000
Author(s)
Joseph~undefined~undefined~undefined~undefined~undefined Lenhart, J H. VanZanten, Joy Dunkers, Richard~undefined~undefined~undefined~undefined~undefined Parnas
A fluorescent probe, covalently grafted to glass, can be used to study the glass/resin interphase region near the surface. A blue shift in fluorescence during resin cure can be monitored when the grafted dye is immersed in epoxy. The position of the