MODES IN UNIDIRECTIONAL COMPOSITES UNDER TRANSVERSE LOADING
AdTech Systems Research Inc.
Univ. of Dayton Research Institute
NIST, Wright Laboratory
paper reports on our attempts to demonstrate potential failure
modes under combined thermal and transverse loading of unidirectional
composites and to validate the predictions of an analytical
model through careful design and testing of composite specimens.
Several fiber/matrix combinations are being considered with
appropriate variations of the fiber-matrix interfacial bond
strength and processing conditions. The interfacial bond strength
is reduced in one set of specimens by applying a release agent
to the surface of the fiber prior to its incorporation in the
matrix. Curing is done both at room and at elevated temperature
to account for thermal residual stresses induced from the mismatch
in the coefficients of thermal expansion of the constituents.
The experimental technique including specimen preparation, test
procedures and detection of the sequence of failure events is
described. The correlation between the experimental and analytical
results is fairly reasonable.