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The application of the theory of linear fracture mechanics to quasi-brittle, glass-reinforced-plastic composites is an important first step in understanding the basic mechanisms of failure of these materials. In the study, a simple test technique sensitive to small changes in the material and/or environmental variables is developed based on fracture mechanics concepts. Using the stress-intensity factor K sub I c as the evaluating parameter, six different resin-glass combinations were tested. The results of these tests indicate that (a) there is no difference in the fracture strength of composites made with either E-glass or S-glass, (b) composites with 5-mil-diam fibers have a lower resistance to crack propagation than those with conventional 0.4-mil-diam fibers, and (c) a filament-wound composite has a much lower fracture toughness in the B-staged state than in the fully cured state. In another phase of the study, the effect of water immersion was investigated. These tests demonstrate that with the exception of the composite made with the large-diameter (5-mil) fibers there is no systematic decline in fracture strength due to water immersion for periods up to 6 months. (Author)

  • Corporate Authors:

    Naval Research Laboratory

    Stennis Space Center, MS  United States  39529-5004
  • Authors:
    • Sanford, Robert J
    • Stonesifer, Fred R
  • Publication Date: 1970-7-29

Media Info

  • Pagination: 23 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00015281
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Files: TRIS
  • Created Date: May 13 1972 12:00AM