Microstructural And Mechanical Properties Of Human Ribs Joseph

Introduction
CHAPTER 1
The human thorax serves an essential purpose by protecting vital organs responsible
for the circulation and respiration of the individual. Any injury to its components can have
a direct effect on the performance of these organs that are essential to life. It is for these
reasons that the human thorax is the focus of the current research.
The purpose of this study was to determine the correlation between microstructural
characteristics of the human rib and their response during dynamic three-point bending.
Dynamic bending was chosen to gain a better understanding of the viscoelastic properties
of human ribs. Strength characteristics under dynamic loading are important for the
development of injury criteria that are used in a wide range of applications, one of which
being automotive safety restraints.
Previous research performing impact sled tests on cadaver subjects have frequently
found rib fracture to be the most common skeletal injury (Alem 1978, Crandall 1997,
Kallieris 1998, Cromack 1975, Patrick 1967, 1974, Ramet 1979). This is concurrent with a
survey of the National Automotive Sampling System (NASS) performed by Crandall et al.
(1994). Projected national trends for occupants incurring an Abbreviated Injury Score or
AIS ≥ 3 in the years 1984 thru 1992 indicated that thoracic injuries were the second most
common injury among 2 and 3 point belt wearers. A thoracic injury of an AIS ≥ 3 would
indicate an occupant incurring at least 3 to 4 rib fractures. A survey of 314 occupants in
automotive accidents showed that rib fracture was the most common skeletal injury
(Dalmotas 1980). The high occurrence rate of rib fracture suggests that there is room for
improvement in the current state of automotive restraint technology.
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