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Thermal Microcracking in Celion 6000/PMR-15 Graphite/Polyimide

  • C. T. Herakovich
  • J. G. GavisJr.
  • J. S. Mills

Abstract

Six laminate configurations were subjected to five different thermal exposures in the temperature range 78K to 603K (−320°F to 625°F), and then studied using microscopy and x-ray to determine the characteristics of microcracks formed during the thermal loadings. The laminates studied were: [03903]s, [02/902]s, [(0/90)3]s, [45/−45/0/90]s, [0/45/90/−45]s, and [0/60/0/−60]s. The material system investigated was found to be free of cracks after curing, but microcracks did develop in most laminates when cooled from 603K (625°F) by quenching in ice water or liquid nitrogen. Crack density was dependent on laminate configuration and rate of cooling. Microcracks present at free edges extended across the entire width of the specimens. The [45/−45/0/90]s laminate proved to be very resistant to microcracking for all thermal loadings. The thermal load required to initiate microcracking, determined using laminate analysis with stress and temperature dependent material properties, compared reasonably well with experimental results.

Keywords

Residual Stress Thermal Loading Free Edge Crack Density Thermal Exposure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Spain, R. G., “Thermal Microcracking of Carbon Fibre/Resin Composites,” Composites, pp. 33–37, March, 1971.Google Scholar
  2. 2.
    Novak, R. C. and DeCrescente, M. A., “Fabrication Stresses in Graphite-Resin Composites,” J. of Engineering for Power, Vol. 92, pp. 377–380, October, 1970.CrossRefGoogle Scholar
  3. 3.
    Molcho, A. and Ishai, O., “Thermal Cracking of C.F.R.P. Laminates,” Society for the Advancement of Material and Process Engineering, Vol. 10, pp. 255–262, October, 1978.Google Scholar
  4. 4.
    Lee, B. L. and McGarry, F. J., “Study of Processing and Properties of Graphite Fiber/High Temperature Resin Composites,” AMMRC CTR 76–10, April, 1976.Google Scholar
  5. 5.
    Hahn, H. T. and Pagano, N. J., “Curing Stresses in Composite Lamiantes,” Journal of Composite Materials, Vol. 9, p. 91, 1975CrossRefGoogle Scholar
  6. 6.
    Cavano, P. J. and Winters, W. E., “PMR Polyimide/Graphite Fiber Composite Fan Blades,” NASA-CR-135113, December 15, 1976.Google Scholar
  7. 7.
    Weitsman, Y., “Residual Thermal Stresses Due to Cool-Down of Epoxy-Resin Composites,” J. Applied Mechanics, Vol. 46, September, 1979.Google Scholar

Copyright information

© Plenum Press, New York 1980

Authors and Affiliations

  • C. T. Herakovich
    • 1
  • J. G. GavisJr.
    • 2
  • J. S. Mills
    • 3
  1. 1.Engineering Science & MechanicsVirginia Tech.BlacksburgUSA
  2. 2.National Aeronautics & Space Admin.Langley Research Ctr.HamptonUSA
  3. 3.McDonnell Douglas Astronautics CompanyHuntington BeachUSA

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