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· The fatigue behavior of the
polymeric
matrix short fiber composite is frequency dependent. At frequencies
that provide large hysteretic heating of the matrix, the temperature increase
reduces the matrix Youngs modulus.
· The
reduced Young's
modulus decreases the effective fiber length by changing
the transfer length required to obtain the isostrain condition.
· As the fatigue
curves show, a reduction
in effective fiber aspect ratio can lead to a large decrease in fatigue
life if the initial aspect ratio is below 100.
· With short fiber systems, fiber alignment may vary. The off-axis
fibers will increase the probability of local fiber-matrix debonding and
incipient crack formation.
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