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  • Open Daily: 10am - 10pm
    Alley-side Pickup: 10am - 7pm

    3038 Hennepin Ave Minneapolis, MN
    612-822-4611

Open Daily: 10am - 10pm | Alley-side Pickup: 10am - 7pm
3038 Hennepin Ave Minneapolis, MN
612-822-4611
Evaluation of Delamination Onset and Growth Characterization Methods Under Mode I Fatigue Loading

Evaluation of Delamination Onset and Growth Characterization Methods Under Mode I Fatigue Loading

Nasa, National Aeronautics and Space Adm

Paperback

Astronomy & Space

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ISBN10: 1793972990
ISBN13: 9781793972996
Publisher: Independently Published
Published: Jan 13 2019
Pages: 34
Weight: 0.23
Height: 0.07 Width: 8.50 Depth: 11.00
Language: English
Double-cantilevered beam specimens of IM7/8552 graphite/epoxy from two different manufacturers were tested in static and fatigue to compare the material characterization data and to evaluate a proposed ASTM standard for generating Paris Law equations for delamination growth. Static results were used to generate compliance calibration constants for reducing the fatigue data, and a delamination resistance curve, GIR, for each material. Specimens were tested in fatigue at different initial cyclic GImax levels to determine a delamination onset curve and the delamination growth rate. The delamination onset curve equations were similar for the two sources. Delamination growth rate was calculated by plotting da/dN versus GImax on a log-log scale and fitting a Paris Law. Two different data reduction methods were used to calculate da/dN. To determine the effects of fiber-bridging, growth results were normalized by the delamination resistance curves. Paris Law exponents decreased by 31% to 37% after normalizing the data. Visual data records from the fatigue tests were used to calculate individual compliance constants from the fatigue data. The resulting da/dN versus GImax plots showed improved repeatability for each source, compared to using averaged static data. The Paris Law expressions for the two sources showed the closest agreement using the individually fit compliance data. Murri, Gretchen B. Langley Research Center NASA/TM-2013-217966, L-20229, NF1676L-16086

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