Optimisation of toughness and strength properties in fibre composites with controlled interfaces

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:143168

Kim, J K; Mai, Y W ^[1]

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1. Univ. of Sydney (Australia). Dept. of Mechanical Engineering

A novel method is presented to achieve both high strength and high fracture toughness of fiber composites by means of a microductile interlayer between fiber and matrix. Experiments conducted on epoxy matrix composites reinforced with unidirectional Kevlar and carbon fibers (KFRP and CFRP) with a thin layer of thermoplastic coating, e.g. polyvinyl alcohol (PVAL), on the fiber show promising results for transverse fracture toughness without any significant loss in strength properties. Variation of fracture toughness with temperature is a direct manifestation of the dependence of the interface properties on the parameter studied. Interlaminar fracture toughness determined in mode 1 and mixed mode 1/2 delamination is also shown to be encouraging. Surface analysis of the fiber and composite interfaces confirms the distinctive failure mechanisms between the composites with and without the PVAL coating. A micromechanics analysis of the total fracture toughness arising from major failure mechanisms gives good agreement with experimental results. Characterization of the interface properties, including interfacial fracture toughness, residual clamping stress and coefficient of friction, using a fiber pull-out model based on a shear-lag analysis is discussed and applied to evaluate experimental data obtained in these composites.

• OSTI ID: 143168
• Report Number(s): CONF-930246--; ISBN 0-87339-251-5
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COATINGS
COMPOSITE MATERIALS
DEPOSITION
FRACTURE PROPERTIES
INTERFACES
MECHANICAL PROPERTIES
PVA
TENSILE PROPERTIES