Accession Number : ADA303920

Title :   Characterization of Delamination Onset and Growth in a Composite Laminate.

Descriptive Note : Technical memo.,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION HAMPTON VA LANGLEY RESEARCH CEN TER

Personal Author(s) : O'Brien, T. K.

PDF Url : ADA303920

Report Date : JAN 1981

Pagination or Media Count : 63

Abstract : The onset and growth of delaminations in unnotched 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 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. (MM)

Descriptors :   *LAMINATES, *DELAMINATION, *GRAPHITE EPOXY COMPOSITES, COMPOSITE MATERIALS, FINITE ELEMENT ANALYSIS, STATIC LOADS, TENSILE STRESS, STIFFNESS, CRACKING(FRACTURING), ENERGY TRANSFER, STRAIN(MECHANICS), STRENGTH(MECHANICS), STRAIN RATE, IMPACT STRENGTH, CORRELATION, CURVATURE, FATIGUE(MECHANICS), FAILURE(MECHANICS), CYCLIC LOADS.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE