Accession Number : ADA306079

Title :   Stress Concentration Around Broken Filaments in a Filament-Stiffened Sheet.

Descriptive Note : Technical note,

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

Personal Author(s) : Fichter, W. B.

PDF Url : ADA306079

Report Date : OCT 1969

Pagination or Media Count : 35

Abstract : Stress distributions around single and double cuts (groups of adjacent broken filaments) in an idealized composite sheet consisting of parallel tension-carrying filaments embedded in a shear-carrying matrix are analyzed by an influence-function technique. Static-load concentration factors for two equal collinear cuts are obtained and are compared with some related results for a single cut. Dynamic-load concentration factors, corresponding to sudden breaking ot filaments, also are obtained tor two ot the simplest double-cut cases. In addition, matrix shear forces are investigated for some single-cut and double-cut cases. Finally, loads in broken filaments are calculated for some single-cut cases, and their implications in some current failure analyses of composite materials are briefly discussed. The interaction between two collinear cuts is essentially local and is roughly confined to separation distances on the order of the cut length. For closely spaced cuts, however, the interaction between cuts is seen to be pronounced. For a single cut, an expression analogous to the filament load concentration factor is obtained for the maximum shear force in the matrix as a function ot the cut length. The results suggest that for some combinations of constituent mechanical properties, the composite might be more susceptible to filament tensile failure at some cut lengths, but more susceptible to matrix shear failure at others. (MM)

Descriptors :   *FIBER REINFORCED COMPOSITES, *FILAMENTS, *STRESS CONCENTRATION, SHEAR PROPERTIES, COMPOSITE MATERIALS, STATIC LOADS, DISPLACEMENT, THESES, GLASS, SHEAR STRESSES, SHEETS, LIGHTWEIGHT, DYNAMIC LOADS, EPOXY COMPOSITES, FAILURE(MECHANICS), CUTTING.

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE