Experiments and micromechanical models for creep-rupture in polymer matrix composites: Progress report for period June 15, 1984-June 14, 1987

Technical Report · Mon Dec 01 04:00:00 EST 1986

OSTI ID:7007782

Phoenix, S L

The research thrust has been to develop micromechanical probability models and conduct critical experiments on the failure of polymer matrix composites under high, sustained loads. Tensile failure of such composites is a complex statistical process involving scattered failure of fibers at flaw sites, and local overloading and failure of neighboring fibers by way of stress transfer through the matrix which may creep and debond in time. Failure results from the subsequent development of a catastrophic crack. These models are ultimately to be used to develop life prediction methodologies, accelerated test techniques, and superior 'microengineered' composites. Recent theoretical progress has included a new recursive formulation which yields a key asymptotic scaling law for strength and lifetime; this is also a new development in modern percolation theory. A key characteristic distribution function results which embodies all local statistical and micromechanical activity, and is now amenable to 'supercomputer' calculation. Progress has also been made in developing a self-similar formulation for micromechanical stress redistribution under a power law creeping matrix. Experimental advances include creep-rupture results for single Kevlar 49 aramid fibers at elevated temperatures, creep-rupture results for graphite fiber/epoxy microcomposites, the development of a single fiber composite test as an advanced technique for studying statistics for fiber strength and fiber/matrix debonding, microindentation techniques for studying matrix creep and debonding, and the development of research equipment for high-precision fabrication of microcomposites.

• Research Organization: Cornell Univ., Ithaca, NY (USA). Sibley School of Mechanical and Aerospace Engineering
• DOE Contract Number: FG02-84ER45112
• OSTI ID: 7007782
• Report Number(s): DOE/ER/45112-3; ON: DE87003567
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603* -- Materials-- Properties
ARAMIDS
CARBON
COMPOSITE MATERIALS
CREEP
ELEMENTAL MINERALS
ELEMENTS
EPOXIDES
FAILURES
FIBERS
FILAMENTS
GRAPHITE
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
MINERALS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
POLYMERS
RESEARCH PROGRAMS
RUPTURES
STRESSES
SYNTHETIC MATERIALS