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  • 1
    Electronic Resource
    Electronic Resource
    In situ sensor monitoring and intelligent control of the resin transfer molding process (1994)
    Brookfield, Conn. : Wiley-Blackwell
    Polymer Composites 15 (1994), S. 299-305 
    Details
    ISSN: 0272-8397
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: An intelligent closed-loop expert control system has been developed for automated control of the resin transfer molding process of a graphite fiber preform using an epoxy resin, E905L. The sensor model system has been developed to make intelligent decisions based on the achievement of landmarks in the cure process, such as full preform impregnation, the viscosity, and the degree of cure of the resin rather than time or temperature. In-situ frequency dependent electromagnetic sensor (FDEMS) and the Loos resin transfer model are used to monitor and control the processing properties of the epoxy resin during RTM impregnation and cure of an advanced fiber architecture stitched preform. Once correlated with viscosity (η) and degree of cure (α), the FDEMS sensor monitors and the RTM processing model predicts the reaction advancement of the resin, viscosity and the impregnation of the fabric. This provides a direct means for monitoring, evaluating, and controlling intelligently the progress of the RTM process in situ in the mold throughout the fabrication process and for verification of the quality of the composites.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pc.750150408
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Design and characterization of thermosetting polyimide structural adhesive and composite matrix systems (1997)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 35 (1997), S. 2943-2954 
    Details
    ISSN: 0887-624X
    Keywords: phenyl ethynyl ether imides ; amorphous or semicrystalline morphology ; volatile free thermosetting matrix ; structural adhesives ; composites ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fully cyclized, organo soluble, phenylethynyl-terminated, ether-imide oligomers of 2-10,000 g/mol (Mn) were prepared by the reaction of 2,2′-bis[4-(3,4-dicarboxyphenoxy)phenyl]-propane dianhydride (bisphenol-A dianhydride, BPADA) with a stoichiometric excess of either para, meta, or isomeric mixtures of phenylene diamine and phenylethynylphthalic anhydride (4-PEPA) endcapper. High para-containing oligomers produced semicrystalline powders, but the all meta isomer was completely amorphous. The lower molecular weight oligomers displayed an attractive low viscosity melt and were cured to very high gel content networks at 350-380°C for 30-90 min. The cured 3000 g/mol oligomers showed a (DSC) glass transition temperature (Tg) of 267°C and produced tough, solvent-resistant films. Excellent adhesion to surface-treated titanium alloys was achieved, as judged by single-lap shear measurements. Resin infusion molding was conducted, which permitted low-void, graphite-fabric composite panels to be prepared. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 2943-2954, 1997
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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    Paper (German National Licenses)
  • 3
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    Static and dynamic fracture toughness of epoxy/alumina composite with submicron inclusions (2004)
    Springer
    Details
    Publication Date: 2004-02-01
    Print ISSN: 0022-2461
    Electronic ISSN: 1573-4803
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Springer
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    PAPER CURRENT
  • 4
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    Modeling the curing process of thick-section autoclave cured composites (1985)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Temperature gradients are significant during cure of large area, thick-section composites. Such temperature gradients result in nonuniformly cured parts with high void contents, poor ply compaction, and variations in the fiber/resin distribution. A model was developed to determine the temperature distribution in thick-section autoclave cured composites. Using the model, long with temperature measurements obtained from the thick-section composites, the effects of various processing parameters on the thermal response of the composites were examined. A one-dimensional heat transfer model was constructed for the composite-tool assembly. The governing differential equations and associated boundary conditions describing one-dimensional unsteady heat-conduction in the composite, tool plate, and pressure plate are given. Solution of the thermal model was obtained using an implicit finite difference technique.
    Keywords: COMPOSITE MATERIALS
    Type: Proceedings of the 2nd Annual Review of the Center for Composite Materials and Structures; 23 p
    Format: text
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    NASA TECHNICAL REPORTS
  • 5
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    Matrix Characterization and Development for the Vacuum Assisted Resin Transfer Molding Process (2001)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: The curing kinetics and viscosity of an epoxy resin system, SI-ZG-5A, have been characterized for application in the vacuum assisted resin transfer molding (VARTM) process. Impregnation of a typical carbon fiber perform provided the test bed for the characterization. Process simulations were carried out using the process model, COMPRO, to examine heat transfer and curing kinetics for a fully impregnated panel, neglecting resin flow. The predicted viscosity profile and final degree of cure were found to be in good agreement with experimental observations.
    Keywords: Nonmetallic Materials
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Modeling the curing process of thermosetting resin matrix composites (1986)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A model is presented for simulating the curing process of a thermosetting resin matrix composite. The model relates the cure temperature, the cure pressure, and the properties of the prepreg to the thermal, chemical, and rheological processes occurring in the composite during cure. The results calculated with the computer code developed on the basis of the model were compared with the experimental data obtained from autoclave-curved composite laminates. Good agreement between the two sets of results was obtained.
    Keywords: COMPOSITE MATERIALS
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Thermoplastic matrix composite processing model (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The effects the processing parameters pressure, temperature, and time have on the quality of continuous graphite fiber reinforced thermoplastic matrix composites were quantitatively accessed by defining the extent to which intimate contact and bond formation has occurred at successive ply interfaces. Two models are presented predicting the extents to which the ply interfaces have achieved intimate contact and cohesive strength. The models are based on experimental observation of compression molded laminates and neat resin conditions, respectively. Identified as the mechanism explaining the phenomenon by which the plies bond to themselves is the theory of autohesion (or self diffusion). Theoretical predictions from the Reptation Theory between autohesive strength and contact time are used to explain the effects of the processing parameters on the observed experimental strengths. The application of a time-temperature relationship for autohesive strength predictions is evaluated. A viscoelastic compression molding model of a tow was developed to explain the phenomenon by which the prepreg ply interfaces develop intimate contact.
    Keywords: COMPOSITE MATERIALS
    Type: NASA-CR-176639 , NAS 1.26:176639 , VPI-E-85-21 , IR-57
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    In-situ measurement of processing properties during fabrication in a production tool (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: Progress is reported on the use of frequency-dependent electromagnetic measurements (FDEMs) as a single, convenient technique for continuous in situ monitoring of polyester cure during fabrication in a laboratory and manufacturing environment. Preliminary FDEM sensor and modeling work using the Loss-Springer model in order to develop an intelligent closed-loop, sensor-controlled cure process is described. FDEMs using impedance bridges in the Hz to MHz region is found to be ideal for automatically monitoring polyester processing properties continuously throughout the cure cycle.
    Keywords: QUALITY ASSURANCE AND RELIABILITY
    Type: Annual Conference on Advanced Composites; Sept. 13-15, 1988; Dearborn, MI; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 9
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    Monitoring cure of composite resins using frequency dependent electromagnetic sensing techniques (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: A nondestructive in situ measurement technique has been developed for monitoring and measuring the cure processing properties of composite resins. Frequency dependent electromagnetic sensors (FDEMS) were used to directly measure resin viscosity during cure. The effects of the cure cycle and resin aging on the viscosity during cure were investigated using the sensor. Viscosity measurements obtained using the sensor are compared with the viscosities calculated by the Loos-Springer cure process model. Good overall agreement was obtained except for the aged resin samples.
    Keywords: QUALITY ASSURANCE AND RELIABILITY
    Type: Technical Conference of the American Society for Composites; Sept. 25-29, 1988; Seattle, WA; United States
    Format: text
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    NASA TECHNICAL REPORTS
  • 10
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    The development of an alternative thermoplastic powder prepregging technique (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-07-12
    Description: An alternative powder prepregging technique is discussed that is based on the deposition of powder onto carbon fibers that have been moistened using an ultrasonic humidifier. The dry fiber tow is initially spread to allow a greater amount of the fiber surface to be exposed to the powder, thus ensuring a significant amount of intimate contact between the fiber and the matrix. Moisture in the form of ultrafine water droplets is then deposited onto the spread fiber tow. The moisture promotes adhesion to the fiber until the powder can be tacked to the fibers by melting. Powdered resin is then sieved onto the fibers and then tacked onto the fibers by quick heating in a convective oven. This study focuses on the production of prepregs and laminates made with LaRC-TPI (thermoplastic polyimide) using this process. Although the process appears to be successful, early evaluation was hampered by poor interfacial adhesion. The adhesion problem, however, seems to be the result of a material system incompatibility, rather than being influenced by the process.
    Keywords: COMPOSITE MATERIALS
    Type: Journal of Thermoplastic Composite Materials (ISSN 0892-7057); 5; 14-31
    Format: text
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    NASA TECHNICAL REPORTS
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