A5058123694- Mechanical Behavior of Composites
- Fiber-reinforced polymer composites
- Textile materials and evaluations
- Advanced Fiber Optic Sensors
- Polymer Nanocomposites and Properties
- Epoxy Resin Curing Processes
- Natural Fiber Reinforced Composites
- Material Properties and Processing
- Synthesis and properties of polymers
- High-Velocity Impact and Material Behavior
- Polymer crystallization and properties
- Composite Material Mechanics
- Occupational Health and Performance
- Adhesion, Friction, and Surface Interactions
- Additive Manufacturing and 3D Printing Technologies
- Industrial Vision Systems and Defect Detection
- Forensic Fingerprint Detection Methods
- Graphene research and applications
- Energetic Materials and Combustion
- Innovative concrete reinforcement materials
- High voltage insulation and dielectric phenomena
- Advanced ceramic materials synthesis
- Manufacturing Process and Optimization
- Nuclear Physics and Applications
- Fullerene Chemistry and Applications
National Institute of Standards and Technology
2013-2023
Material Measurement Laboratory
2015-2020
National Institute of Standards
2002-2014
Materials Science & Engineering
2009
Drug Enforcement Administration
2009
Building Research Institute
2009
Measurement Specialties (Germany)
2006
Engineering Systems (United States)
2005
Texas A&M University
1994
The single fiber fragmentation test (SFFT) as currently devised involves the repeated fracture of a embedded in matrix dogbone specimen until process ceases (saturation). average fragment length (lƒ) obtained from this procedure is then used shear-lag model to determine fiber-matrix (F-M) interfacial shear strength (IFSS) (tIFSS). This testing methodology has many issues that have precluded it becoming standardized method. In 1991 Galiotis et al. developed model-independent non-saturation...
It is well known that the fiber-matrix interface in many composites has a profound influence on composite performance. The objective of this study to understand composition and concentration coupling agent strength by coating E-glass fibers with solutions containing mixture hydrolyzed propyl trimethoxysilane (PTMS) n -aminopropyl (APS). failure behavior were assessed single-fiber fragmentation test (SFFT), while structure silane was studied terms its thickness ellipsometry, morphology atomic...
Abstract A minimally invasive testing methodology was developed to monitor the in‐service performance of soft body armor. In spirit single fiber test standard, ASTM C 1557‐03, diameter measured at five equally spaced locations along a 6‐cm gauge length specimen. addition, specimen modified by placing reflecting tape just outside allow use laser extensometer for directly measuring displacement and hence, strain. This found be reproducible provide data that normally distributed based on...
This study focuses on understanding the effect of cellulose nanocrystals (CNCs) glass fiber/epoxy interfacial interactions. The fibers (GF) were coated with solutions containing nanomaterial. parameters that investigated CNC surface chemistry, concentration, and dispersing medium, i.e., aqueous solution only versus emulsions. To determine coatings adhesion, specimens a single GF in an epoxy matrix prepared for coating by varying formulations. shear stress (IFSS) was determined fiber...
Abstract The present study indicates that a distribution of alkylammonium chain lengths in the interlayer montmorillonite (MM) results greater degree dispersion into an epoxy matrix (or possibly different polymer matrices) and improved ultimate tensile strengths. This hypothesis is supported by x‐ray diffraction (XRD) data from modified MM clays, which clearly shows increase d ‐spacing does not result improvement Additional support obtained DSC analyses first second heats treated clays...
Abstract Research has indicated that the folding of ballistic fibers comprising soft body armor may be a factor in performance deterioration been observed. To quantify impact this failure mechanism on performance, an apparatus was designed and built to simulate occur while vest is use. This device systematically folds woven fabric yarns enable assessment fiber properties. After cycling piece poly(benzoxazole) (PBO) for 80,000 cycles, 41% reduction both ultimate tensile strength strain PBO...
A method is presented to test whether the conversion of mass spectrum a polydisperse analyte its molecular distribution quantitative. Mixtures samples with different average masses, coupled Taylor's expansion mathematical formalism, were used ascertain reliability distributions derived from spectra. Additionally, describes how may be corrected if degree bias within certain defined limits. This was demonstrated on C(60) fullerenes functionalized ethylpyrrolidine groups measured by...
Abstract Precise measurements of fiber break regions have been made during the single fragmentation test (SFFT) procedure on E‐glass/diglycidyl ether bisphenol‐A (DGEBA)/meta‐phenylenediamine (m‐PDA) specimens. From these measurements, location and size each fragment was determined, resulting information used to construct maps tested fiber. By comparing maps, process supports random along length Since interfacial shear strength (IFSS) or stress transfer coefficient (I‐STC) is obtained from...
Abstract In this paper, a brief review of the fiber-matrix interphase/interface region is given for carbon- and glass-fiber composites. The substructure discussed in terms three interphases: (a) fiber interphase (FI), (b) sizing (SI), (c) matrix (MI), two interface regions: FI-SI SI-MI interface. These substructures are synthesis ideas advanced by Ishida Koenig Drzal. schematic model deformation behavior originally Bascom reconstructed to include research results from above researchers. To...
Abstract The goals of the research effort described in this article are to develop a framework evaluate improvements next‐generation fibers used soft body armor and anticipate long‐term performance potential fiber deterioration. This date has included effect folding on exploring interaction between specific strain energy their sound velocity. Previous work lab noted severe drop‐off tensile strength strain‐to‐failure poly( p ‐phenylene benzobisoxazole) (PBO) when subjected repeated folding....
Abstract In this paper, we examine the regions of debonding between fibers and matrix surrounding fiber breaks formed during single fragmentation tests. The are accompanied by areas surface fiber. With increasing applied strain, lengths these debonded generally increase. At end test, tensile strain adjacent to debond is an order magnitude higher than (40% vs. 4%). Although edges typically remain attached at same locations on fragments, propagation along fragments under has been observed in...
Because of the premature failure in-service soft-body armor containing ballistic fiber poly[(benzo-[1,2-d:5,4-d′]-benzoxazole-2,6-diyl)-1,4-phenylene] (PBO), Office Law Enforcement Standards (OLES) at National Institute and Technology (NIST) initiated a research program to investigate reasons for this develop testing methodologies protocols ensure that these types failures do not reoccur. In report focused on stability benzoxazole ring is characteristic PBO fibers, Holmes, G. A.; Rice, K.;...