Micromechanical behavior of single-fiber type and hybrid microcomposites

Thesis/Dissertation · Wed Jan 01 04:00:00 EST 1992

OSTI ID:7039389

Qiu, Yiping

Single-fiber type and hybrid microcomposites were fabricated using Kevlar {reg sign} 149 as the low elongation (LE) fiber and S-glass fibers as the high elongation fiber using a DER 331/DER 732 epoxy mixture (70/30, w/w). In tensile tests, it was found that Kevlar{reg sign} 149 fiber was significantly stronger in the microcomposite than as a single filament. For the hybrid microcomposite, Kevlar{reg sign} 149 fibers usually broke one by one. A positive hybrid effect for the failure strain but a negative hybrid effect for the strength of the hybrid were observed. The tensile modulus of the hybrid microcomposite followed the rule of mixtures well. The fiber/matrix interface properties were investigated using the single-fiber pull-out from a microcomposite (SFPOM) test and the microbond test. SFPOM test reflected the feeling of the fibers in a real composite, showing the decrease of interfacial shear strength (IFSS) with fiber volume fraction increase. To predict the stress-rupture lifetime of a hybrid composite, a stochastic model was proposed assuming that the failure of LE fibers in a hybrid follows a continuous time Markov chain.

• Research Organization: Cornell Univ., Ithaca, NY (United States)
• OSTI ID: 7039389
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
360603* -- Materials-- Properties
ARAMIDS
COMPOSITE MATERIALS
FABRICATION
FIBERS
GLASS
MATERIALS
MATERIALS TESTING
MATHEMATICAL MODELS
MECHANICAL TESTS
PETROCHEMICALS
PETROLEUM PRODUCTS
PLASTICS
STOCHASTIC PROCESSES
SYNTHETIC MATERIALS
TESTING