INTRODUCTION - Injury Biomechanics and Control: Optimal Protection from Impact - page 1

CHAPTER 1
INTRODUCTION
The authors would like to share with the readers a unique experience in the
systematic use of the methods of optimal control for shock isolation systems
that will be applied to assorted structures intended to mitigate injuries. This
topic uses the theory of optimal shock isolation, which was developed in the
1950s for the protection of engineering systems from intensive shock loads,
and extends the use to problems associated with reducing the risk of injuries
to people who are subjected to an impact load. Impact-induced injuries may
occur in vehicle accidents, at industrial or construction sites, in sports, and in
military or antiterrorism activities. Depending on the situation, people may
be protected from impact loads using devices such as bullet-proof vests,
helmets, seat belts, or air bags. Alternatively, the source of the load can be
modified to reduce the potential for injury. To be effective, these protective
devices must be properly designed so that the forces and displacements
experienced are below injury tolerance levels.
Within the framework of optimal shock isolation, protecting a person
from injurious impact loads requires the introduction of a medium between
the person and the structure that is subject to shock disturbances. This
medium is known a shock isolator , whereas the structure to which an impact
load is directly applied is called the base . Different structures can play the
roles of the base and the isolator. For a motorcycle helmet, for example, the
base is the shell of the helmet, and the isolator is the padding or the armature
that separates the shell from the head. In a crashworthy automobile, the base
is the body or frame of the vehicle, while seat belts and air bags are the
isolators. In general, the isolators can be passive or active. Passive isolators