Accession Number : ADA185938

Title :   Composite Reliability Enhancement via Preloading.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Bell, David K

PDF Url : ADA185938

Report Date : Jun 1987

Pagination or Media Count : 98

Abstract : Many Navy applications of composites, including ships' superstructures, submarine air flasks and missile rocket motor casings, require high strength and reliable materials. Composite strength reliability is dictated by individual fiber breaks at low loads (lower tail) and the accumulation of the fiber failure sites. This study examined the effects of applying a preload to a graphite epoxy composite tow prior to complete polymerization of the matrix. The objective was to break the (inevitable) weak fibers and minimize the effects of the associated stress concentrations, subsequently limiting the clustering of the fiber failures. By eliminating the lower tail, the shape of the Weibull distribution is reduced, thereby enhancing composite reliability. Keywords: Composite materials, Preloading, Integrated fiber testing, Graphite epoxy.

Descriptors :   *COMPOSITE MATERIALS, *RELIABILITY, AIR, FAILURE, FIBERS, FLASKS, GRAPHITE, GUIDED MISSILES, HIGH STRENGTH, INTEGRATED SYSTEMS, LOW STRENGTH, MATERIALS, NAVY, OPTIMIZATION, ROCKET ENGINE CASES, ROCKET ENGINES, SHIP STRUCTURAL COMPONENTS, SITES, STATISTICAL DISTRIBUTIONS, STRENGTH(GENERAL), STRESS CONCENTRATION, SUBMARINES, SUPERSTRUCTURES, TAIL ASSEMBLIES, TEST AND EVALUATION, WEIBULL DENSITY FUNCTIONS, LOADS(FORCES), CLUSTERING, GRAPHITED MATERIALS, EPOXY COMPOSITES, SINGLE CRYSTALS, STRESS STRAIN RELATIONS, STRANDS, DEFORMATION, THESES

Subject Categories : Laminates and Composite Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE