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Test methods for the dynamic mechanical properties of polymeric materials. Final report

Description: Various test geometries and procedures for the dynamic mechanical analysis of polymers employing a mechanical spectrometer have been evaluated. The methods and materials included in this work are forced torsional pendulum testing of Kevlar/epoxy laminates and rigid urethane foams, oscillatory parallel plate testing to determine the kinetics of the cure of VCE with Hylene MP, oscillatory compressive testing of B-3223 cellular silicone, and oscillatory tensile testing of Silastic E and single Kev… more
Date: June 1, 1980
Creator: Baker, G.K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Computer programs, to determine credible regions for Weibull distribution

Description: Computer software for analyzing life test data with a Weibull distribution is given. The programs calculate and plot the 95, 90, 50 and 5% highest probability density contours and the maximum likelihood estimators on the same frame for all sets of data. They also calculate the maximum likelihood estimator of mean life and conservative 95, 90, 50 and 5% credible intervals on mean life. The programs are used to analyze data on the lifetimes of Kevlar/Epoxy spherical vessels and the results are gi… more
Date: unknown
Creator: Agrawal, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Prediction of long-term failure in Kevlar 49 composites

Description: Creep rupture data in Kevlar 49 epoxy usually exhibit considerable scatter: the coefficient of variation (CV) about the mean failure time at a given stress exceeds 100%. Quasi-static strength data, in contrast, shows little scatter: <4% CV for pressure vessels and <10% for impregnated strands. In this paper analysis of existing creep rupture data on Kevlar epoxy vessels at four storage pressures has produced an interesting and useful result. It was found that a significant portion of the scatte… more
Date: January 1, 1982
Creator: Gerstle, F.P. Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Development of Kevlar parachute webbings

Description: This paper describes the development of Kevlar webbings for parachute applications. Evaluation of existing webbings and a study of the effects of filling yarn denier and pick count on tensile and joint strength provided data for fabric design. Measurements of warp crimp as a function of filling denier and pick count demonstrated the relationship between warp crimp and strength. One newly developed webbing had higher strength efficiency and another had higher joint efficiency than comparable exi… more
Date: January 1, 1991
Creator: Ericksen, R.H.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Design of large aperture, low mass vacuum windows

Description: Large vacuum vessels are employed downstream of fixed targets in High Energy Physics experiments to provide a long path for particles to traverse without interacting with air molecules. These vessels generally have a large aperture opening known as a vacuum window which employs a thin membrane to preserve the vacuum environment yet allows the particles to pass through with a minimal effect on them. Several large windows have been built using a composite of Kevlar/Mylar including circular window… more
Date: January 1, 1993
Creator: Leonhardt, W.J. & Mapes, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Design and performance of a parachute for the recovery of a 760-lb payload

Description: A 26-ft-diameter ribbon parachute deployed using a pilot parachute system has been developed at Sandia National Laboratories for the recovery of a 760-lb payload released at subsonic and transonic speeds. The wide range of deployment dynamic pressures led to the design, utilizing wind tunnel testing and computer simulation, of a unique pilot parachute system verified in full-scale flight tests. Performance data from 20 full-scale flight tests were used to evaluate system performance and structu… more
Date: January 1, 1991
Creator: Waye, D.E.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Bound water in Kevlar 49 fibers

Description: From elemental analyses, thermogravimetric-mass spectroscopy studies and re-evaluation of previous water diffusion studies in Kevlar 49 fibers it is concluded that these fibers can contain two types of sorbed moisture. The fibers can absorb up to approx. 6 wt % loosely bound water with an activation energy for outgassing by desorption of 6 kcal/mole. This loosely bound water is a direct result of the presence of Na/sub 2/SO/sub 4/ impurities and the perturbations they induce on the packing of t… more
Date: April 1, 1981
Creator: Garza, R. G.; Pruneda, C. O. & Morgan, R. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

F111 Crew Escape Module Pilot Parachute

Description: A successfully deployment of a parachute system highly depends on the efficiency of the deployment device and/or method. There are several existing methods and devices that may be considered for a deployment system. For the F111 Crew Escape Module (CEM), the recovery parachute system deployment is initiated by the firing of a catapult that ejects the complete system from the CEM. At first motion of the pack, a drogue gun is fired, which deploys the pilot parachute system. The pilot parachute sy… more
Date: January 1, 1991
Creator: Tadios, E.L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

344 cm x 86 cm low mass vacuum window

Description: The LBL Heavy Ion Spectrometer System (HISS) superconducting magnet contains a 1 m x 3.45 m x 2 m vacuum tank in its gap. A full aperture thin window was needed to minimize background as the products of nuclear collisions move from upstream targets to downstream detectors. Six windows were built and tested in the development process. The final window's unsupported area is 3m/sup 2/ with a 25 cm inward deflection. The design consists of a .11 mm Nylon/aluminum/polypropylene laminate as a gas sea… more
Date: August 1983
Creator: Reimers, R.M.; Porter, J.; Meneghetti, J.; Wilde, S. & Miller, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Measurements of laser generated impulse

Description: The total impulse delivered by pulsed-laser illumination of planar targets in vacuum. Data are presented for several target materials (aluminum and some of its alloys, titanium, and kevlar/epoxy structural composite) as a function of incident fluence for laser wavelengths of 248 nm, 2.8 ..mu..m, and 10.6 ..mu..m. 4 tabs.
Date: January 1, 1986
Creator: King, T.; Barrus, D.; Dingus, R.; Osborne, Z. & Phipps, C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Fabrication of a Kevlar liner assembly

Description: Several liner assemblies were fabricated with Kevlar 49 and epoxy using various wet layup and prepreg processes. A production process, using prepreg material, was developed for fabricating the liner and a wet layup molding process was used to fabricate the Kevlar hat-shaped tunnels. Fabrication of the tunnels using Kevlar prepreg with an autoclave curving process was evaluated.
Date: July 1, 1980
Creator: Schloman, A.H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Characterization of Kevlar-49 yarn

Description: A study was made to determine the variability in Dupont's 380-denier Kevlar-49 yarn. Both in-spool and spool-to-spool variations in tensile strength, cross-sectional area, and chemical composition were determined for one lot of material.
Date: July 1, 1978
Creator: Thompson, W. F.; Powell, G. L. & Lever, W. E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Characterization of Kevlar 49 fibers by electron paramagnetic resonance. Final report, 20 May 1981-20 June 1982. [Radicals induced by ultraviolet or fracture]

Description: EPR was used to investigate the free radicals created in Kevlar 49 fibers by stress-induced and photo-induced macromolecular chain scissions. Mn/sup +2/ ions were identified from the EPR spectrum of frozen solutions of concentrated sulfuric acid containing Kevlar 49. Other ions present are Cu/sup +2/, and possibly Fe/sup +3/, Cr/sup +3/, and Ti/sup +3/. EPR lineshape anisotropy indicates that some of the metal ions and first coordinate spheres are oriented. The concentration of stress-induced r… more
Date: June 20, 1982
Creator: Brown, I.M. & Sandreczki, T.C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Sequestering carbon dioxide in industrial polymers: Building materials for the 21st century

Description: This study was undertaken to determine the possibility of developing beneficial uses for carbon dioxide as a key component for a large-volume building product. Such a use may provide an alternative to storing the gas in oceanic sinks or clathrates as a way to slow the rate of global warming. The authors investigated the concept that carbon dioxide might be used with other chemicals to make carbon-dioxide-based polymers which would be lightweight, strong, and economical alternatives to some type… more
Date: June 1, 1993
Creator: Molton, P. M. & Nelson, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Shelf life determination of epoxy prepregs and film adhesives. Final report

Description: Kinetic data describing the cure of a Kevlar/epoxy prepreg and an epoxy film adhesive were determined by the use of Differential Scanning Calorimetry. For the Kevlar/epoxy prepreg, a correlation was found between the heat of reaction and percent resin flow; a similar correlation was found between the heat of reaction and lap-shear strength for the film adhesive. An equation was derived for the determination of the B stage time required to yield an epoxy prepreg possessing the desired flow prope… more
Date: January 1, 1979
Creator: Parker, B. G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

An acousto-ultrasonic NDE technique for monitoring material anisotropy

Description: A simpler and better way of monitoring the anisotropy of fiber-reinforced composite materials, based on the acousto-ultrasonic approach, is presented. In this approach, time of flight of the acousto-ultrasonic waves AU, rather than the stress wave factor, is measured. Two fundamental Lamb modes are generated under the first critical frequency: one is the first antisymmetric mode traveling with a slower velocity while the another is the first symmetric mode traveling with a faster speed. The lat… more
Date: August 1, 1992
Creator: Chien, Hual Te; Sheen, Shuh Haw & Raptis, A. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

A novel CFD/structural analysis of a cross parachute

Description: A novel CFD/structural analysis was performed to predict functionality of a cross parachute under loadings near the structural limits of the parachute. The determination of parachute functionality was based on the computed structural integrity of the canopy and suspension lines. In addition to the standard aerodynamic pressure loading on the canopy, the structural analysis considered the reduction in fabric strength due to the computed aerodynamic heating. The intent was to illustrate the feasi… more
Date: December 31, 1993
Creator: LaFarge, R. A.; Nelsen, J. M. & Gwinn, K. W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Design of large aperture, low mass vacuum windows

Description: Large vacuum vessels are employed downstream of fixed targets in High Energy Physics experiments to provide a long path for particles to traverse without interacting with air molecules. These vessels generally have a large aperture opening known as a vacuum window which employs a thin membrane to preserve the vacuum environment yet allows the particles to pass through with a minimal effect on them. Several large windows have been built using a composite of Kevlar/Mylar including circular window… more
Date: July 1, 1993
Creator: Leonhardt, W. J. & Mapes, M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Sequestering carbon dioxide in industrial polymers: Building materials for the 21st century

Description: This study was undertaken to determine the possibility of developing beneficial uses for carbon dioxide as a key component for a large-volume building product. Such a use may provide an alternative to storing the gas in oceanic sinks or clathrates as a way to slow the rate of global warming. The authors investigated the concept that carbon dioxide might be used with other chemicals to make carbon-dioxide-based polymers which would be lightweight, strong, and economical alternatives to some type… more
Date: June 1, 1993
Creator: Molton, P. M. & Nelson, D. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Characterizaion of a Kevlar-filled epoxy molding compound

Description: A Kevlar-filled epoxy molding compound was tested in fiber lengths of 6 and 13 mm. Kevlar is an aromatic polyamide fiber. Both materials were tested for tensile, flexural, and compressive strengths at 24/sup 0/C. The 6 mm fiber length material was also tested at temperatures of 79 and 135/sup 0/C. Thermal behavior was determined for both materials over a temperature range of 24 to 220/sup 0/C. At 135/sup 0/C the 6-mm fiber length material retained 59.1 percent of its tensile strength, 51.7 perc… more
Date: February 1, 1979
Creator: McFarland, J. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Shelf-life determination of epoxy prepregs and film adhesives

Description: Epoxy prepregs and film adhesives are composed of partially cured (''B'' staged) epoxy resins and, in the case of the prepregs, a fiber matrix. Purchased epoxy prepreg lots typically are accepted or rejected on the basis of resin content, gel time, and resin flow. The shelf-life storage conditions of both materials generally are based on vendor recommendation. At The Bendix Corporation, Kansas City Division, there has been concern recently with shelf-life aging of a Kevlar/epoxy prepreg. At pre… more
Date: January 1, 1978
Creator: Parker, B. G. & Smith, C. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Characteristics of laser cutting Kevlar laminates. Topical report

Description: Comparison of laser-cut and machined samples of Kevlar/epoxy laminates has shown that material properties are not degraded by use of the laser. With present techniques and a 1000-W CO/sub 2/ laser, the maximum laminate thickness that can be cut satisfactorily is 9.5 mm. Power requirements, edge taper, and kerf width for various thicknesses have been established. Partial-depth cuts, controlled and repeatable to within 0.5 mm, have been produced in Kevlar/epoxy laminates by scanning the material … more
Date: January 1, 1979
Creator: Van Cleave, R.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Super-strong self-reinforcing polymeric matrices formed by the first super-strong polymers

Description: The design of super-strong (SS) polymers to form the first SS self-reinforcing polymeric matrices is described. Solidified SS liquid- crystalline polymers (LCPs) are designed to be the first polymers to have good compressive strengths, as well as to have tensile strengths and tensile moduli significantly greater than existing strong LCPs (i.e., backbone LCPs, such as Kevlar). (These SS LCPs have also been designed with certain features to give good solubilities and processabilities.) 17 refs., … more
Date: January 1, 1989
Creator: Dowell, F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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