JOBR: “2121_c052” — 2006/2/6 — 19:55 — page 10 — #10
52-10
Biomedical Engineering Fundamentals
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10
5
2
1
0
500
1000
1500
2000
2500
3000
HIC
Risk
of lif
e-threatening br
ain injur
y (%)
Injury risk curve for HIC when (
t
2
–
t
i
) s 15 msec
HIC = 1000 represents a 15%
risk of life-threatening
Brain injury if (
t
2
–
t
1
) S 15 msec
FIGURE 52.7
Head injury risk curve based on HIC.
52.4.2 The Injury-Assessment Tool
The response and tolerance data acquired from cadaveric studies are used to design human-like surrogates,
known as
anthropomorphic test devices (ATD). These surrogates are required not only to have biofidelity
and the ability to simulate human response but also need to provide physical measurements that are
representative of human injury. In addition, they are designed to be repeatable and reproducible. The
current frontal impact dummy is the Hybrid III family of dummies ranging from the 95th percentile male to
the 3-year-old infant. The 50th percentile male dummy is human like in many of its responses, including
that of the head and neck. The head consists of an aluminum headform covered by an appropriately
designed vinyl “skin” to yield human-like acceleration responses for frontal and lateral impacts against a
flat, rigid surface. Two-dimensional physical models of the brain were proposed by Margulies et al. [1990]
using a silicone gel in which preinscribed grid lines would deform under angular acceleration. No injury
criterion is associated with this gel model.
The dummy neck was designed to yield responses in flexion and extension that would fit within the
corridors shown in Figure 52.2 and Figure 52.3. The principal function of the dummy neck is to place the
head in the approximate position of a human head in the same impact involving a human occupant.
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