Accession Number : ADA134171

Title :   Size Effect and Strength Variability of Unidirectional Composites.

Descriptive Note : Interim rept. Jan-Sep 83,

Corporate Author : CALIFORNIA UNIV LOS ANGELES DEPT OF MATERIALS SCIENCE AND ENGINEERING

Personal Author(s) : Batdorf,S B ; Ghaffarian,Reza

PDF Url : ADA134171

Report Date : Sep 1983

Pagination or Media Count : 25

Abstract : Statistical theories have been proposed for damage accumulation and tensile failure of unidirectionaly reinforced fibrous composites. These theories involve the mechanical properties of the constituent fibers, the geometry of the composite, and some inadequately known functions such as stress distribution in the vicinity of single and multiple fiber breaks. As a result in trying to correlate theory and experiment some quantities have to be treated as unknown parameters. It was found that use of Hedgepeth and Van Dyke's stress concentration factors led to good agreement between theory and Bullock's data on graphite epoxy only when the overload length of fiber at crack tips was assumed to have an unrealistically large value. A possible explanation is that the Hedgepath and Van Dyke stress concentration factors were calculated for composites the fiber spacing is quite irregular. A theory is developed for strength of irregularly constructed composites and compared with experiment. Taking the effect into account improves agreement in the case of one experiment and impairs agreement in the case of another.

Descriptors :   *FIBER REINFORCED COMPOSITES, *UNIDIRECTIONAL, *MECHANICAL PROPERTIES, STATISTICAL MECHANICS, SIZES(DIMENSIONS), STRENGTH(MECHANICS), VARIATIONS, MICROSTRUCTURE, SHEAR PROPERTIES, FAILURE(MECHANICS), LINEARITY

Subject Categories : Laminates and Composite Materials
      Mechanics

Distribution Statement : APPROVED FOR PUBLIC RELEASE