Accession Number : ADA305477

Title :   Fundamental Analysis of the Failure of Polymer-Based Fiber Reinforced Composites.

Descriptive Note : Final rept.,

Corporate Author : BATTELLE COLUMBUS DIV OH

Personal Author(s) : Kanninen, M. F. ; Rybicki, E. F. ; Griffith, W. I. ; Broek, D.

PDF Url : ADA305477

Report Date : APR 1976

Pagination or Media Count : 49

Abstract : A mathematical model is being developed that will permit predictions of the strength of fiber reinforced composites cOntaining known flaws to be made from the basic properties of their constituents. The approach is to embed a local heterogeneous region (LHR) surrounding the crack tip into an anisotropic elastic continuum. The intent is to have the model (1) permit an explicit analysis of the micromechanical processes involved in the fracture process, and (2) remain simple enough to be useful in practical computations. Material properties used in the analysis are to be obtained from a concurrent experimental program being carried out at Virginia Polytechnic Institute and State University. Computations for arbitrary flaw size and orientation under arbitrary applied load combinations have been performed for unidirectional composites with linear elastic-brittle constituent behavior. The mechanical properties were nominally those of graphite epoxy. With the rupture properties arbitrarily varied to test the capability of the model to reflect real fracture modes in fiber composites, it is shown in the report that fiber breakage, matrix crazing, crack bridging, matrix-fiber debonding, and axial splitting can all occur during a period of (gradually) increasing load prior to catastrophic fracture. Of most importance, the computations reveal qualitatively the sequential nature of the stable crack growth process that precedes fracture in composites. Quantitative comparisons with the VPISU experimental results on edge-notched unidirectional graphite epoxy specimens have also been made and were found to be in fair agreement. (MM)

Descriptors :   *POLYMERS, *FIBER REINFORCED COMPOSITES, *FAILURE(MECHANICS), STRESS STRAIN RELATIONS, MATHEMATICAL MODELS, LOAD DISTRIBUTION, MICROSTRUCTURE, COMPOSITE MATERIALS, STIFFNESS, ELASTIC PROPERTIES, ORIENTATION(DIRECTION), GRAPHITE, MATRIX MATERIALS, RUPTURE, STRENGTH(MECHANICS), FRACTURE(MECHANICS), CRACK PROPAGATION, DEFECTS(MATERIALS), BRITTLENESS, ANISOTROPY, SPLITTING, CATASTROPHIC CONDITIONS, BRIDGES, GRAPHITE EPOXY COMPOSITES, UNIDIRECTIONAL, BEARING CAPACITY, CRAZING.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE