Accession Number : ADA304589

Title :   A Temperature Dependent Fatigue Failure Criterion for Graphite/Epoxy Laminates.

Descriptive Note : Technical memo.,

Corporate Author : NATIONAL AERONAUTICS AND SPACE ADMINISTRATION MOFFETT FIELD CA AMES RESEARCH CENTER

Personal Author(s) : Rotem, Assa ; Nelson, Howard G.

PDF Url : ADA304589

Report Date : OCT 1978

Pagination or Media Count : 19

Abstract : A fatigue failure criterion applicable to composite materials is developed and applied to predict the fatigue behavior of graphite/epoxy laminates with particular emphasis on the influence of temperature. Tensile stress-strain curves and tension-tension fatigue curves for various unidirectional, angle-ply and symmetrically balanced laminates were developed at test temperatures of 25C, 74C and 114C. In general for most laminates a reduction in both static strength and fatigue strength is observed with increasing temperature. This reduction appeared more severe in fatigue loading than in static tensile loading and most severe where the shear stress in the lamina is the dominate failure mode. Through an analytical formulation of shifting functions for the influences of temperature, all fatigue data are shown to be capable of being reduced to a single reference curve at some temperature. Additionally, examples are given which demonstrate the capability of the fatigue failure criterion to predict failure of complex symmetrically balanced laminates from relevant parameters obtained from the observed behavior of unidirectional and angle-ply laminates.

Descriptors :   *EPOXY LAMINATES, *FATIGUE TESTS(MECHANICS), *GRAPHITE EPOXY COMPOSITES, STRESS STRAIN RELATIONS, FATIGUE LIFE, STRESS ANALYSIS, STATIC LOADS, TENSILE STRESS, FIBER REINFORCED COMPOSITES, MATRIX MATERIALS, STRENGTH(MECHANICS), TEMPERATURE GRADIENTS, MATHEMATICAL PREDICTION, SHEAR STRESSES, TENSION, FAILURE(MECHANICS), STATIC TESTS.

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE