STP775

    Characterization of Delamination Onset and Growth in a Composite Laminate

    Published: Jan 1982


      Format Pages Price  
    PDF Version (472K) 28 $25   ADD TO CART
    Complete Source PDF (5.4M) 28 $55   ADD TO CART


    Abstract

    The onset and growth of delaminations in unnotched [±30±309090¯]s graphite-epoxy laminates is described quantitatively. These laminates, designed to delaminate at the edges under tensile loads, were tested and analyzed. Delamination growth and stiffness loss were monitored nondestructively. Laminate stiffness decreased linearly with delamination size. The strain energy release rate, G, associated with delamination growth, was calculated from two analyses. A critical G for delamination onset was determined, and then was used to predict the onset of delaminations in [+45n/−45n/0n/90n]s (n = 1,2,3) laminates. A delamination resistance curve (R-curve) was developed to characterize the observed stable delamination growth under quasi-static loading. A power law correlation between G and delamination growth rates in fatigue was established.

    Keywords:

    graphite-epoxy, delamination, ply-cracking, rule of mixtures, stiffness loss, strain energy release rate, R, -curve, fatigue, growth law, composite materials


    Author Information:

    O'Brien, TK
    Research engineer, Structures Laboratory, U. S. Army Research and Technology Laboratories (AVRADCOM), National Aeronautics and Space Administration-Langley Research Center, Hampton, Va.


    Paper ID: STP34325S

    Committee/Subcommittee: E08.08

    DOI: 10.1520/STP34325S


    CrossRef ASTM International is a member of CrossRef.