Biomedical Engineering Reference
In-Depth Information
250
Human forehead impact
Wo odpecker's pecking
Human forehead impact
Wo odpecker's pecking
10
Human nose impact
Human nose impact
200
150
8
100
6
1
1
1
1
18
4
2
0
0
0
2468
Time (ms)
10
12
14
16
02468
Time (ms)
10
12
14
16
(a)
(b)
Human forehead impact
Wo odpecker's pecking
Human forehead impact
Wo odpecker's pecking
1.5
1.5
Human nose impact
Human nose impact
1.0
1.0
0.5
0.5
0.0
0.0
-
0.5
-
0.5
-
1.0
-
1.0
-
1.5
-
1.5
0
2
468
Time (ms)
10
12
14
16
0
2468
Time (ms)
10
12
14
16
(c)
(d)
FIgure 19.5
(See color insert.)
Stress/strain rate time histories of the skull and brain for the human and
woodpecker: (a) stress history on the forehead on the skull; (b) stress history on the occiput on the skull;
(c) strain rate history on the forehead on the brain; and (d) strain rate history on the occiput on the brain.
not work until the end of collision. It seems that the hyoid bone may play a role as a “safety belt” for
the woodpecker's head to some extent.
19.4 Summary and aPPlICatIonS oF the modelS
In this chapter, the finite element models of the human head and woodpecker head were developed
to compare the effect of different factors on the load transfer during impact. The modeling method,
including the geometric structure of the human skull and woodpecker skull, material properties of
the cranial bone and brain, meshing technology, and boundary conditions, are presented in detail.
The dynamic FE commercial package LS-Dyna Version 971 (Livermore Software Inc.) (Wollensak
and Spoerl, 2004) was used to simulate the dynamic responses during impact. As a robust analysis
tool, explicit dynamic solution is ideal for simulating physical events that happen in a short time. It
provided a solid platform for parametric analysis.
The conclusions of the present study are summarized as follows: The special beak and hyoid bone
were major factors to nonimpact injuries. The long hyoid bone has played a role as a “safety belt”
to the woodpecker's head, especially after impact. Beak morphology was found to affect impact
force and brain strain rate. The woodpecker's sophisticated shock absorption system is a coopera-
tive phenomenon, with no single factor able to achieve the function. The design of an intelligent
helmet or impact-related, injury-resistant device would be lightened greatly by optimization of the
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