On fracture phenomena in advanced fiber composite materials.The extension of linear elastic fracture mechanics (LEFM) from metallic alloys to advanced fiber composite laminates is considered. LEFM is shown to be valid for both isotropic and anisotropic homogeneous continua; the applicability of LEFM to advanced fiber composites is thus dependent on the validity of a homogeneous model of such materials. An experimental program to determine the validity of such a model for graphite/epoxy laminates is reviewed. Such laminates are found to have an apparent fracture toughness, from which it is inferred that a homogeneous material model is valid for the particular specimen geometry and composite laminates considered. Strain energy release rates are calculated from the experimentally determined fracture toughness of the various laminates. These strain energy release rates are found to lie in one of two groups, depending upon whether crack extension required fiber failure or matrix failure. The latter case is further investigated. It is concluded that matrix failure is governed by the tensile stress normal to the crack path.
Document ID
19720041740
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Konish, H. J., Jr.
Swedlow, J. L.
Cruse, T. A. (Carnegie-Mellon University Pittsburgh, Pa., United States)
Date Acquired
August 6, 2013
Publication Date
April 1, 1972
Subject Category
Structural Mechanics
Report/Patent Number
AIAA PAPER 72-384
Meeting Information
Meeting: Structures, Structural Dynamics, and Materials Conference