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  • 1
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    Technology integration box beam failure study (1992)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The objective of this paper is to describe current results from an on-going study of the mechanisms that led to the failure of the TIBB. Experimental and analytical results are presented. Experimental results include load, strain, and deflection data for the TIBB (Technology Integration Box Beam). An analytical investigation was conducted to compliment the experimental investigation and to gain additional insight into the TIBB structural response. Analytical results include strain and deflection results from a global analysis of the TIBB. A local analysis of the failure region is being completed. These analytical results are validated through comparisons with the experimental results from the TIBB tests. The experimental and analytical results from the TIBB tests are used to determine a sequence of events that may have resulted in failure of the TIBB. A potential cause of failure is high stresses in a stiffener runout region. Typical analytical results are presented for a stiffener runout specimen that is being defined to simulate the TIBB failure mechanisms. The results of this study are anticipated to provide better understanding of potential failure mechanisms in composite aircraft structures, to lead to future design improvements, and to identify needed analytical tools for design and analysis.
    Keywords: STRUCTURAL MECHANICS
    Type: FAA, Ninth DOD(NASA)FAA Conference on Fibrous Composites in Structural Design, Volume 2; p 673-68
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Technology integration box beam failure study (1993)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: Composite structures have the potential to be cost-effective, structurally efficient primary aircraft structures. The Advanced Composites Technology (ACT) Program has the goal to develop the technology to exploit this potential for heavily loaded aircraft structures. As part of the ACT Program, Lockheed Aeronautical Systems Company completed the design and fabrication of the Technology Integration Box Beam (TIBB). The TIBB is an advanced composite prototype structure for the center wing section of the C-130 aircraft. Lockheed subjected the TIBB to downbending, upbending, torsion and combined upbending and torsion load conditions to verify the design. The TIBB failed at 83 percent of design ultimate load for the combined upbending and torsion load condition. The objective of this paper is to describe the mechanisms that led to the failure of the TIBB. The results of a comprehensive analytical and experimental study are presented. Analytical results include strain and deflection results from both a global analysis of the TIBB and a local analysis of the failure region. These analytical results are validated by experimental results from the TIBB tests. The analytical and experimental results from the TIBB tests are used to determine a sequence of events that resulted in failure of the TIBB. A potential cause of failure is high stresses in a stiffener runout region. Analytical and experimental results are also presented for a stiffener runout specimen that was used to simulate the TIBB failure mechanisms.
    Keywords: STRUCTURAL MECHANICS
    Type: Third NASA Advanced Composites Technology Conference, Volume 1, Part 2; p 951-965
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Fatigue failure load indicator (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An indicator for recording the load at which a fatigue specimen breaks during the last cycle of a fatigue test is described. A load cell is attached to the specimen which is alternately subjected to tension and compression loads. The output of the load cell which is proportional to the load on the specimen is applied to the input of a peak detector. Each time the specimen is subjected to a compression load, means are provided for applying a positive voltage to the rest of the peak detector to reset it. During the last cycle of the tension load the peak detector measures the maximum load on the specimen. Means are provided for disconnecting the load cell from the peak detector when there is a failure in the specimen.
    Keywords: STRUCTURAL MECHANICS
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    NASA TECHNICAL REPORTS
  • 4
    Electronic Resource
    Electronic Resource
    High gloss of extruded high impact polystyrene sheet. A microscopical study of sheet morphology (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 7 (1963), S. S51 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1963.070070638
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  • 5
    Electronic Resource
    Electronic Resource
    High gloss of extruded high impact polystyrene sheet. A microscopical study of sheet morphology (1963)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 7 (1963), S. 1731-1741 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Morphological changes effected in the two-phase high impact polystyrene system by several methods of securing high surface gloss of extruded sheet were studied microscopically. In the glazing process changes occur in refractive index of the copolymer particles and in the matrix. Excessive glazing may result in oxidative damage. The effects of temperature and oxidation and temperature alone on the copolymer particles have been investigated.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1963.070070514
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of crosslinking on the properties of poly(2-hydroxyethyl methacrylate) hydrogels (1991)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 189 (1991), S. 195-205 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2-Hydroxyethyl-methacrylat wurde durch Initiierung mit γ-Strahlung in Masse mit zwei verschiedenen tetrafunktionellen Monomeren (Ethylenglycol-dimethacrylat und 1,2-Bis(acryloxymethyl)-tetramethyldisiloxan) und einem hexafunktionellen Monomeren (1,1,1-Trimethylolpropan-trimethacrylat) als Vernetzungsmittel copolymerisiert. Die erhaltenen Xerogele wurden anschließend mit Wasser bis zum Erreichen der Gleichgewichtsquellung behandelt. Um die drei Vernetzungsmittel vergleichen zu können, wurde unter Berücksichtigung von Molmasse und Funktionalität der Xerogele die theoretische Konzentration an Vernetzungsstellen zwischen 0,032 und 0,644 mol/l variiert. Die relative Hydrophobie der drei Vernetzungsmittel hat einen ausschlaggebenden Einfluß sowohl auf die Gleichgewichtsquellung als auch auf den Elastizitätsmodul der gequollenen Gele. Der Gehalt an nicht-einfrierbarem Wasser in mit 1,1,1-Trimethylol-propan-trimethacrylat vernetzten Gelen wurde anhand von DSC-Untersuchungen analysiert. Das Verhältnis von nicht-einfrierbarem zum Gesamtgehalt an Wasser in den Gelen nimmt mit steigender Vernetzungsdichte zu.
    Notes: By means of γ-irradiation 2-hydroxyethyl methacrylate has been copolymerized in bulk with two different tetrafunctional monomers, ethylene glycol dimethacrylate and 1,3-bis(acryloxymethyl) tetramethyl disiloxane and with a hexafunctional monomer, 1,1,1-trimethylolpropane trimethacrylate. The resultant xerogels were subsequently swollen to equilibrium in water. In order to allow a comparison among the three crosslinkers, their molar masses and funtionalities were taken into account, the theoretical crosslink concentrations being varied from 0.032 to 0.644 mol dm-3. The relative hydrophobicity of the three crosslinkers was found to have a significant effect on both the equilibrium swelling and elastic modulus of the swollen gels. Non-freezing water in several gels crosslinked with 1,1,1-trimethylolpropane trimethacrylate was analysed by differential scanning calorimetry (DSC). The proportion of non-freezing water in the gel relative to the overall water content was found to increase with increasing crosslink density.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1991.051890118
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  • 7
    Electronic Resource
    Electronic Resource
    A facile synthesis of polyamides from aromatic diisocyanates and dicarboxylic acid catalyzed by Lewis acids (1996)
    Weinheim : Wiley-Blackwell
    Macromolecular Rapid Communications 17 (1996), S. 897-903 
    Details
    ISSN: 1022-1336
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Aromatic polyamides were prepared by an AlCl3 or HCl-catalyzed polymerization of toluene diisocyanate or methylenebis(phenyl isocyanate) with adipic acid at low temperatures (≤100°C) in a short reaction time (3-4 h). The intrinsic viscosity of the polymers was approximately 1.1 dL/g as determined at 25°C with m-cresol as solvent, indicating that the polyamides obtained by this method have relatively high molecular weights. The polymers exhibit high glass transition temperatures and good thermal stability.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/marc.1996.030171208
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  • 8
    Electronic Resource
    Electronic Resource
    Studies on the application of matrix-assisted-laser-desorption-ionisation time-of-flight mass spectrometry to the determination of chain transfer coefficients in free radical polymerization (1998)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 199 (1998), S. 2403-2408 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The chain transfer coefficient (Cs) has been determined for 2-methyl-2-propanethiol (t-Bu-SH) in the solution polymerization of methyl methacrylate (MMA). Three different analytical methods were investigated. The Mayo and chain length distribution (CLD) methods yielded consistent Cs values of 0.12 and 0.13, respectively, at 60°C. A third, new approach to the evaluation of Cs values was also attempted using Matrix-Assisted-Laser-Desorption-Ionisation (MALDI) Time-Of-Flight Mass Spectrometry to analyse the end-groups of the polymer chains. The values of Cs obtained from MALDI analyses were not consistent with the other two methods and the relative intensities of the peaks with different end-groups were found to be dependent on the selection of cation.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Critically evaluated rate coefficients for free-radical polymerization, 2.Part 1: cf. ref.1. Propagation rate coefficients for methyl methacrylate (1997)
    Weinheim : Wiley-Blackwell
    Macromolecular Chemistry and Physics 198 (1997), S. 1545-1560 
    Details
    ISSN: 1022-1352
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Pulsed-laser polymerization (PLP) in conjunction with molar mass distribution (MMD) measurement is the method of choice for determining the propagation rate coefficient kp in free-radical polymerizations. The authors, members of the IUPAC Working Party on Modeling of kinetics and processes of polymerization, collate results from using PLP-MMD to determine kp as a function of temperature T for bulk free-radical polymerization of methyl methacrylate at low conversions and ambient pressure. Despite coming from several different laboratories, the values of kp are in excellent agreement and obey consistency checks. These values are therefore recommended as constituting a benchmark data set, one that is best fitted by \documentclass{article}\pagestyle{empty}\begin{document}$ k_p = 10^{6,427} {\rm L} \cdot {\rm mol}^{ - 1} \cdot {\rm s}^{ - 1} \exp \left( {\frac{{ - 22,36{\rm kJ} \cdot {\rm mol}^{ - 1} }}{{R \cdot T}}} \right) $\end{document}The 95% joint confidence interval for these Arrhenius parameters is also given. In so doing, we describe the most appropriate statistical methods for fitting kp(T) data and then obtaining a joint confidence interval for the fitted Arrhenius parameters. As well, we outline factors which impose slight limitations on the accuracy of the PLP-MMD technique for determining kp, factors which may apply even when this technique is functioning well. At the same time we discuss how such systematic errors in kp can be minimized.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1997.021980518
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  • 10
    Electronic Resource
    Electronic Resource
    Free energy, heat, and entropy changes accompanying the sorption of water vapor by proteinsContribution from the Institute of Polymer Research, Polytechnic Institute of Brooklyn. (1948)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 3 (1948), S. 16-21 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Recently published measurements of moisture sorption vs. relative humidity for a series of proteins have previously been analyzed in a way which permits calculation of the integral free energy of sorption for any final pressure of water vapor. The present paper is an extension of these calculations to additional proteins from the list reported by Bull; integral and differential free energies and integral and differential heats and entropies of sorption have been calculated as functions of the amounts of water sorbed onsilk, wool, egg albumin (unlyophilized and heat coagulated), salmine, collagen, gelatin and lactoglobulin (crystalline and lyophilized). All calculations are referred to saturated water vapor as the standard state. Some of the proteins show positive net differential entropies of sorption at low vapor pressures. It is postulated that the partial molal entropy of sorption is made up of two terms, a negative entropy of sorption proper and a positive entropy of solution. Partial rearrangements of the protein chains at the beginning of the sorption process would effectively be an incipient solution which would give rise to a positive partial molal entropy of sorption if the second term is greater than the first. This speculation has support in the fact that the differential entropy of salmine, which dissolves at a relative vapor pressure of about 0.7, begins to show positive values at a relative vapor pressure of 0.35.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1948.120030103
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