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

Technical Report · Mon Jun 01 04:00:00 EDT 1987

OSTI ID:6291349

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 (1) creep-rupture results for single Kevlar 49 aramid fibers at elevated temperatures, (2) creep-rupture results for graphite fiber/epoxy microcomposites, (3) the development of a single fiber composite test as an advanced technique for studying statistics for fiber strength and fiber/matrix debonding, (4) microindentation techniques for studying matrix creep and debonding, and (5) 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: 6291349
• Report Number(s): DOE/ER/45112-4; ON: DE87011708
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360603 -- Materials-- Properties
42 ENGINEERING
420500* -- Engineering-- Materials Testing
99 GENERAL AND MISCELLANEOUS
990220 -- Computers
Computerized Models
& Computer Programs-- (1987-1989)
ACOUSTIC EMISSION TESTING
ACOUSTIC TESTING
COMPOSITE MATERIALS
CREEP
FAILURES
FIBERS
FRACTURE PROPERTIES
MATERIALS
MATERIALS TESTING
MATHEMATICAL MODELS
MECHANICAL PROPERTIES
NONDESTRUCTIVE TESTING
POLYMERS
PROBABILITY
RUPTURES
TESTING