The stresses at the interface of fully bonded and fully disbonded cren
ulated carbon fibers in a carbon matrix are presented. Interface stres
ses for two loading cases, transverse tensile loading and a negative t
emperature change, are discussed. A crenulated fiber is one which has
a wavy or scalloped outer radius, the amplitude and frequency of the w
aviness resulting from the manufacturing process. A square-packed arra
y of fibers is assumed and the results are obtained using the finite-e
lement method. For comparison to the crenulated fiber, the stresses fo
r similarly loaded bonded and disbonded circular fibers are also prese
nted. The level of disbond in each case is measured by the size of the
radial gap between the fiber and the matrix. When fully disbonded, th
e fiber and matrix are assumed to interact only through frictionless e
lastic contact. Results from the fully disbonded case show that mechan
ical interference occurs between the fiber and the matrix. In general,
the results of the study show that the stress levels present with the
crenulated fiber are significantly higher than for the circular fiber
. In particular, large stress concentrations arise in the matrix tange
ntial stress component at high crenulation amplitudes and high crenula
tion frequencies. Overall, the work described provides new insight int
o the complex interactions between fiber and matrix, specifically inte
ractions that reflect on the reality of disbond, and innovations regar
ding fiber architecture.