Biomedical Engineering Reference
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V
=
kFx
Steady-state
wear
We aring
in
Travel distance (
X
)
FIGUre 11.7
Wear rate curve.
PROBLEM 11.2
If a Co-Cr coupled with ultrahigh-molecular-weight polyethylene
(UHMWPE) THR (28 mm head diameter) retrieved after 5 years
in vivo
shows a total surface recession of 0.75 mm (Figure 11.8), find (A) the
annual volume of wear debris, (B) the number of wear particles produced
per year (assume spherical particles 5 μm in diameter), and (C) the appro-
priate value of the wear constant (
k
). (Neglect creep in this calculation.)
ANSWER:
A. Wear volume
V
= 2π
r
2
× 0.75/5
= 185 mm
3
= 1.85 × 10
−7
m
3
0.75 mm
r
= 14 mm
FIGUre 11.8
Polymeric wear in thr (Problem 11.2).
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