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Interphase mechanical properties in epoxy-glass fiber composites as measured by interfacial force microscopy

Description: The research focuses on the measurement of the nanomechanical properties associated with the interphase region of a polymer matrix fiber composite with a nanometer resolution in chemically characterized model composites. The Interfacial Force Microscope (IFM) is employed to measure, with nanometer resolution, the mechanical properties of the interphase region of epoxy/glass fiber composites. The chemistry of the interphase is altered by the adsorption on to the fiber surface a coupling agent, 3-aminopropyltrimethoxy silane ({gamma}-APS) which is known to covalently bond to the glass fiber surface and the epoxy resin. Recent work utilizing FT-IR fiber optic evanescent wave spectroscopy provides a method for the characterization of the interphase chemistry. This technique has been used to investigate the interphase chemistry of epoxy/amine curing agent/amine-terminated organosilane coupling agent/silica optical fiber model composites. This body of work has shown that a substantial fraction of the amine of the organosilane-coupling agent does not participate in a reaction with the epoxy resin. This evidence suggests an interphase that will have mechanical properties significantly different than the bulk epoxy/amine matrix. Previous research has shown that drastic changes occur in the coupling agent chemistry, interphase chemistry, and composite mechanical properties as the amount of adsorbed coupling agent is varied over the industrially relevant range used in this work. A commercially available epoxy resin, EPON 828, and aliphatic amine-curing agent, EPI-CURE 3283, make up the polymer matrix in this study. The reinforcement is silica optical or E-glass fibers.
Date: April 1, 1998
Creator: Winter, R.M. & Houston, J.E.
Partner: UNT Libraries Government Documents Department

Investigation of the Interphase Region in Polymer Matrix - Glass Fiber Reinforced Composites Using the Interfacial Force Microscope

Description: The proposed research was to provide a critical vehicle to enhance South Dakota researchers' abilities to participate in nationally important energy related research while building and strengthening partnerships between the South Dakota School of Mines and Technology and Sandia National Laboratory.
Date: June 30, 2004
Creator: Winter, R. M
Partner: UNT Libraries Government Documents Department

Recovery of Uranium From Fiberglass Air Filters

Description: Abstract: Various procedures for extracting uranium from fiberglass air filters have been tested and compared. Satisfactory results which involve the least amount of handling are obtained by simply washing the material with hot 1:1 hydrochloric acid.
Date: August 5, 1946
Creator: Adams, R. H.; Rogers, J. A. & Brown, K. B.
Partner: UNT Libraries Government Documents Department

Blade system design studies volume II : preliminary blade designs and recommended test matrix.

Description: As part of the U.S. Department of Energy's Wind Partnerships for Advanced Component Technologies (WindPACT) program, Global Energy Concepts, LLC is performing a Blade System Design Study (BSDS) concerning innovations in materials, processes and structural configurations for application to wind turbine blades in the multi-megawatt range. The BSDS Volume I project report addresses issues and constraints identified to scaling conventional blade designs to the megawatt size range, and evaluated candidate materials, manufacturing and design innovations for overcoming and improving large blade economics. The current report (Volume II), presents additional discussion of materials and manufacturing issues for large blades, including a summary of current trends in commercial blade manufacturing. Specifications are then developed to guide the preliminary design of MW-scale blades. Using preliminary design calculations for a 3.0 MW blade, parametric analyses are performed to quantify the potential benefits in stiffness and decreased gravity loading by replacement of a baseline fiberglass spar with carbon-fiberglass hybrid material. Complete preliminary designs are then presented for 3.0 MW and 5.0 MW blades that incorporate fiberglass-to-carbon transitions at mid-span. Based on analysis of these designs, technical issues are identified and discussed. Finally, recommendations are made for composites testing under Part I1 of the BSDS, and the initial planned test matrix for that program is presented.
Date: June 1, 2004
Creator: Griffin, Dayton A. (Global Energy Concepts, LLC, Kirkland, WA)
Partner: UNT Libraries Government Documents Department

Slurry-based fabrication of chopped fiberglass composite preforms

Description: A water-based process for the fabrication of chopped fiberglass preforms is being developed in collaboration with the Automotive Composite Consortium (ACC) and The Budd Company. This slurry process uses hydraulic pressure to form highly compacted fiberglass preforms on contoured, perforated metal screens. The preforms will be used in the development of structural automotive composites. A key objective is to produce preforms having uniform areal density. Computational simulation of variable open area screens, and areal density mapping using a gamma densitometer are discussed.
Date: December 1, 1995
Creator: Moore, G.A.; Johnson, R.W.; Landon, M.D.; Stoots, C.M. & Anderson, J.L.
Partner: UNT Libraries Government Documents Department

Impact of the temperature dependency of fiberglass insulation R-value on cooling energy use in buildings

Description: Building energy models usually employ a constant, room-temperature-measured value for the thermal resistance of fiberglass roof insulation. In summer, however, the mean temperature of roof insulation can rise significantly above room temperature, lowering the insulation`s thermal resistance by 10% to 20%. Though the temperature dependence of the thermal resistance of porous materials like fiberglass has been extensively studied, it is difficult to theoretically predict the variation with temperature of a particular fiberglass blanket, from first principles. Heat transfer within fiberglass is complicated by the presence of three significant mechanisms - conduction through air, conduction through the glass matrix, and radiative exchange within the matrix - and a complex, unknown internal geometry. Purely theoretical models of fiberglass heat transfer assume highly simplified matrix structures and require typically-unavailable information about the fiberglass, such as its optical properties. There is also a dearth of useful experimental data. While the thermal resistances of many individual fiberglass samples have been measured, there is only one practical published table of thermal resistance vs. both temperature and density. Data from this table was incorporated in the DOE-2 building energy model. DOE-2 was used to simulate the roof surface temperature, roof heat flux, and cooling energy consumption of a school bungalow whose temperature and energy use had been monitored in 1992. The DOE-2 predictions made with and without temperature variation of thermal conductivity were compared to measured values. Simulations were also run for a typical office building. Annual cooling energy loads and annual peak hourly cooling powers were calculated for the office building using both fixed and variable thermal conductivities, and using five different climates. The decrease in the R-value of the office building`s roof led to a 2% to 4% increase in annual cooling energy load.
Date: August 1, 1996
Creator: Levinson, R.; Akbari, H. & Gartland, L.
Partner: UNT Libraries Government Documents Department

Calculation and Validation of Thermomechanical Stresses in Flip Chip BGA Using the ATC4.2 Test Vehicle

Description: We report the first in situ measurements of thermomechanical stresses in a 1000 I/O 250 {micro}m pitch piezoresistive flip chip test chip assembled to a 755 I/O 1.0 mm pitch 35 mm Ball Grid Array (BGA). The BGA substrates employed build-up dielectric layers containing micro-vias over conventional fiberglass laminate cores. Experimental data, which include in situ stress and die bending measurements, were correlated to closed form and Finite Element Method (FEM) calculations. Cracking and delamination were observed in some of the experimental groups undergoing temperature cycling. Through use of bounding conditions in the FEM simulations, these failures were associated with debonding of the underfill fillet from the die edge that caused stresses to shift to weaker areas of the package.
Date: March 9, 1999
Creator: Burchett, S.N.; Mitchell, R.T.; Nguyen, L.; Peterson, D.W. & Sweet, J.N.
Partner: UNT Libraries Government Documents Department

The use of carbon fibers in wind turbine blade design: A SERI-8 blade example

Description: The benefit of introducing carbon fibers in a wind turbine blade was evaluated. The SERI-8 wind turbine blade was used as a baseline for study. A model of the blade strength and stiffness properties was created using the 3D-Beam code; the predicted geometry and structural properties were validated against available data and static test results. Different enhanced models, which represent different volumes of carbon fibers in the blade, were also studied for two design options: with and without bend-twist coupling. Studies indicate that hybrid blades have excellent structural properties compared to the all-glass SERI-8 blade. Recurring fabrication costs were also included in the study. The cost study highlights the importance of the labor-cost to material-cost ratio in the cost benefits and penalties of fabrication of a hybrid glass and carbon blade.
Date: March 1, 2000
Creator: ONG,CHENG-HUAT & TSAI,STEPHEN W.
Partner: UNT Libraries Government Documents Department

Pretreatment Optimization of Fiberglass Manufacturing Industrial Wastewater

Description: Wastewater effluent produced in the fiberglass manufacturing industry contains a significant amount of total suspended solids. Environmental regulations require pretreatment of effluent before it is discharged to the municipal wastewater treatment plant. Chemical precipitation by coagulation and flocculation is the method of pretreatment used at the Vetrotex CertainTeed Corporation (VCT). A treatability study was conducted to determine conditions at which the VCT Wastewater Pretreatment Plant could operate to consistently achieve a total suspended solids concentration ≤ 200-mg/L. Jar tests varied pH, polymer dosage, and ferric sulfate dosage. Total suspended solids and turbidity were measured to evaluate treatment performance. The data were used to determine an optimum set of conditions under project guidelines. Of twelve polymers screened, BPL 594 was selected as the most effective polymer. For cost efficiency in the wastewater pretreatment operation, recommendations suggested that treatment chemical injection be electronically controlled according to turbidity of the treated effluent.
Date: December 1998
Creator: Dragoo, Ron
Partner: UNT Libraries

A Summary of the Fatigue Properties of Wind Turbine Materials

Description: Modern wind turbines are fatigue critical machines that are typically used to produce electrical power from the wind. The materials used to construct these machines are subjected to a unique loading spectrum that contains several orders of magnitude more cycles than other fatigue critical structures, e.g., an airplane. To facilitate fatigue designs, a large database of material properties has been generated over the past several years that is specialized to materials typically used in wind turbines. In this paper, I review these fatigue data. Major sections are devoted to the properties developed for wood, metals (primarily aluminum) and fiberglass. Special emphasis is placed on the fiberglass discussion because this material is current the material of choice for wind turbine blades. The paper focuses on the data developed in the U.S., but cites European references that provide important insights.
Date: October 7, 1999
Creator: SUTHERLAND, HERBERT J.
Partner: UNT Libraries Government Documents Department

The Development of Confidence Limits for Fatigue Strength Data

Description: Over the past several years, extensive databases have been developed for the S-N behavior of various materials used in wind turbine blades, primarily fiberglass composites. These data are typically presented both in their raw form and curve fit to define their average properties. For design, confidence limits must be placed on these descriptions. In particular, most designs call for the 95/95 design values; namely, with a 95% level of confidence, the designer is assured that 95% of the material will meet or exceed the design value. For such material properties as the ultimate strength, the procedures for estimating its value at a particular confidence level is well defined if the measured values follow a normal or a log-normal distribution. Namely, based upon the number of sample points and their standard deviation, a commonly-found table may be used to determine the survival percentage at a particular confidence level with respect to its mean value. The same is true for fatigue data at a constant stress level (the number of cycles to failure N at stress level S{sub 1}). However, when the stress level is allowed to vary, as with a typical S-N fatigue curve, the procedures for determining confidence limits are not as well defined. This paper outlines techniques for determining confidence limits of fatigue data. Different approaches to estimating the 95/95 level are compared. Data from the MSU/DOE and the FACT fatigue databases are used to illustrate typical results.
Date: November 9, 1999
Creator: Sutherland, Herbert J. & Veers, Paul S.
Partner: UNT Libraries Government Documents Department

Spectrum Fatigue Lifetime and Residual Strength for Fiberglass Laminates

Description: This report addresses the effects of spectrum loading on lifetime and residual strength of a typical fiberglass laminate configuration used in wind turbine blade construction. Over 1100 tests have been run on laboratory specimens under a variety of load sequences. Repeated block loading at two or more load levels, either tensile-tensile, compressive-compressive, or reversing, as well as more random standard spectra have been studied. Data have been obtained for residual strength at various stages of the lifetime. Several lifetime prediction theories have been applied to the results. The repeated block loading data show lifetimes that are usually shorter than predicted by the most widely used linear damage accumulation theory, Miner's sum. Actual lifetimes are in the range of 10 to 20 percent of predicted lifetime in many cases. Linear and nonlinear residual strength models tend to fit the data better than Miner's sum, with the nonlinear providing a better fit of the two. Direct tests of residual strength at various fractions of the lifetime are consistent with the residual strength models. Load sequencing effects are found to be insignificant. The more a spectrum deviates from constant amplitude, the more sensitive predictions are to the damage law used. The nonlinear model provided improved correlation with test data for a modified standard wind turbine spectrum. When a single, relatively high load cycle was removed, all models provided similar, though somewhat non-conservative correlation with the experimental results. Predictions for the full spectrum, including tensile and compressive loads were slightly non-conservative relative to the experimental data, and accurately captured the trend with varying maximum load. The nonlinear residual strength based prediction with a power law S-N curve extrapolation provided the best fit to the data in most cases. The selection of the constant amplitude fatigue regression model becomes important at the lower stress, higher ...
Date: March 1, 2002
Creator: WAHL, NEIL K.; MANDELL, JOHN F. & SAMBORSKY, DANIEL D.
Partner: UNT Libraries Government Documents Department

ANALYSIS OF VAPORS FROM METHYLENE CHLORIDE EXTRACTS OF NUCLEAR GRADE HEPA FILTER FIBERGLASS SAMPLES

Description: While several organic compounds were detected in the vapor samples used in the reenactment of the preparation of mounts from the extracts of nuclear grade high-efficiency particulate air filter fiberglass samples, the most significant species present in the samples were methylene chloride, phenol, phenol-d6, and 2-fluorophenol. These species were all known to be present in the extracts, but were expected to have evaporated during the preparation of the mounts, as the mounts appeared to be dry before any vapor was collected. These species were present at the following percentages of their respective occupational exposure limits: methylene chloride, 2%; phenol, 0.4%; and phenol-d6, 0.6%. However, there is no established limit for 2-fluorophenol. Several other compounds were detected at low levels for which, as in the case of 2-fluorophenol, there are no established permissible exposure limits. These compounds include 2-chlorophenol; N-nitroso-1-propanamine; 2-fluoro-1,1{prime}-biphenyl; 1,2-dihydroacenaphthylene; 2,5-cyclohexadiene-1,4-dione,2,6-bis(1,1-dimethylethyl); trimethyl oxirane; n-propylpropanamine; 2-(Propylamino)ethanol; 4-methoxy-1-butene; 6-methyl-5-hepten-2-one; and 3,4-dimethylpyridine. Some of these were among those added as surrogates or spike standards as part ofthe Advanced Technologies and Laboratories International, Inc. preparation ofthe extract of the HEPA filter media and are indicated as such in the data tables in Section 2, Results; other compounds found were not previously known to be present. The main inorganic species detected (sulfate, sodium, and sulfur) are also consistent with species added in the preparation of the methylene chloride extract of the high-efficiency particulate air sample.
Date: June 7, 2012
Creator: JM, FRYE; HL, ANASTOS & FC, GUTIERREZ
Partner: UNT Libraries Government Documents Department

Evaluation of ceramic papers and tapes for use as separators in thermal batteries.

Description: Ceramic tapes and papers were evaluated for potential use as separators in high-temperature thermal batteries. The bulk of the tests involved fiberglass tape and borosilicate filter discs. Quartz (SiO{sub 2}) and zirconia (ZrO{sub 2}) materials were also examined to a limited extent. In addition, custom-prepared MgO-coated ceramic discs from Inventek Inc. were evaluated as separators. The tapes and paper discs were impregnated with LiCl-KCl eutectic or LiCl-LiBr-LiF electrolytes using three different techniques. Test discs were punched from the tapes and papers, impregnated with electrolyte and evaluated as separators in Li(Si)/FeS{sub 2} single cells at 400 or 500 C at a steady-state current of 63 or 125 mA/cm{sup 2}. The performance of single cells containing these discs generally improved with increased electrolyte loading for most of the materials in the case of the LiCl-KCl eutectic. Better results were obtained with the paper filter discs than with the tapes. The best results with the paper discs were obtained with Whatman GF/A filter discs. Active lives for cells with these separators were about 85% of standard cells with pressed-powder separators. Good results were obtained in one battery test with the eutectic electrolyte. Mixed results were obtained with the LiCl-LiBr-LiF electrolyte under similar conditions. Higher loadings of electrolyte did not always translate into improved cell performance. Self-discharge reactions are believed responsible. The best overall results were obtained with the Inventek separators. Based on the results of this study, more work in this technology area is merited.
Date: June 1, 2006
Creator: Reinhardt, Frederick William & Guidotti, Ronald Armand
Partner: UNT Libraries Government Documents Department

Development and utilization of composite honeycomb and solid laminate reference standards for aircraft inspections.

Description: The FAA's Airworthiness Assurance NDI Validation Center, in conjunction with the Commercial Aircraft Composite Repair Committee, developed a set of composite reference standards to be used in NDT equipment calibration for accomplishment of damage assessment and post-repair inspection of all commercial aircraft composites. In this program, a series of NDI tests on a matrix of composite aircraft structures and prototype reference standards were completed in order to minimize the number of standards needed to carry out composite inspections on aircraft. Two tasks, related to composite laminates and non-metallic composite honeycomb configurations, were addressed. A suite of 64 honeycomb panels, representing the bounding conditions of honeycomb construction on aircraft, was inspected using a wide array of NDI techniques. An analysis of the resulting data determined the variables that play a key role in setting up NDT equipment. This has resulted in a set of minimum honeycomb NDI reference standards that include these key variables. A sequence of subsequent tests determined that this minimum honeycomb reference standard set is able to fully support inspections over the full range of honeycomb construction scenarios found on commercial aircraft. In the solid composite laminate arena, G11 Phenolic was identified as a good generic solid laminate reference standard material. Testing determined matches in key velocity and acoustic impedance properties, as well as, low attenuation relative to carbon laminates. Furthermore, comparisons of resonance testing response curves from the G11 Phenolic NDI reference standard was very similar to the resonance response curves measured on the existing carbon and fiberglass laminates. NDI data shows that this material should work for both pulse-echo (velocity-based) and resonance (acoustic impedance-based) inspections.
Date: June 1, 2004
Creator: Roach, Dennis Patrick & Rackow, Kirk A.
Partner: UNT Libraries Government Documents Department

HANFORD SITE LOW EXPOSURE PIPELINE REPAIR USING A NON-METALLIC COMPOSITE SYSTEM

Description: At the Department of Energy, Richland Operations (DOE-RL) Hanford site in eastern Washington, a 350 mm (14 inch) diameter high density polyethylene (HDPE) pump recirculation pipeline failed at a bonded joint adjacent to a radiologically and chemically contaminated groundwater storage basin. The responsible DOE-RL contractor, CH2MHill Plateau Remediation Company, applied a fiberglass reinforced plastic (composite) field repair system to the failed joint. The system was devised specifically for the HDPE pipe repair at the Hanford site, and had not been used on this type of plastic piping previously. This paper introduces the pipe failure scenario, describes the options considered for repair and discusses the ultimate resolution of the problem. The failed pipeline was successfully returned to service with minimal impact on waste water treatment plant operating capacity. Additionally, radiological and chemical exposures to facility personnel were maintained as low as reasonably achievable (ALARA). The repair is considered a success for the near term, and future monitoring will prove whether the repair can be considered for long term service and as a viable alternative for similar piping failures at the Hanford site.
Date: November 12, 2009
Creator: Huth, R. J.
Partner: UNT Libraries Government Documents Department