Biomedical Engineering Reference
In-Depth Information
ANSWER:
F, T, F, F, T.
PROBLEM 8.6
Carbon fiber has all of the following desirable characteristics as a PMC-
reinforcing phase
except
A. High tensile strength
B. High bending strength
C. Nonresorbability
D. Little immunogenic activity
E. Cost
ANSWER:
B
. Carbon fibers are strong in tension and relatively low in cost compared
with other, higher-performance materials, especially whiskers. They are
quite chemically inert and thus invoke very modest host responses.
PROBLEM 8.7
A continuous fiber two-phase Reuss PMC has the same
in each phase (complete the sentence).
ANSWER:
Stress.
PROBLEM 8.8
An epoxy-carbon fiber fracture fixation plate such as that shown in
Figure 8.2 is tested in an animal long bone osteotomy model in compari-
son with a stainless steel plate with the same bending stiffness. A greater
degree of callus hypertrophy is noted in fractures treated with the PMC
plates than in those treated with the stainless steel plates. Why?
ANSWER:
A possible explanation is that creep under the screw heads may have
caused premature “decoupling” of the PMC plate from the bone. This
may be a generic design problem with such devices; perhaps it could be
solved by replacing the outer pre-pregs with thin metal sheets.
PROBLEM 8.9
Compared with casts made from “plaster” bandage, those made from
synthetic casting materials are (select the best answer[s])
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