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Implications of velocity change delta-v and energy equivalent speed EES for injury mechanism assessment in various collision configurations
Technical Paper
1998-13-0004
Published September 16, 1998 by International Research Council on Biokinetics of Impact in Switzerland
Sector:
Language:
English
Abstract
Technical tools to describe the crash severity of a vehicle are
the delta-v of the center of gravity of the vehicle considered and
the EES value of the deformation. In a collision without
glance-off, such as a barrier impact with 100% overlap, EES and
delta-v are of similar values. If glance-off occurs in an impact
with only partial overlap, the EES can be considerably higher than
the delta-v, especially with high collision speeds. The theoretical
background is standard knowledge for engineers dealing with
accident reconstruction. However, scientists in the biomechanical
and medical area are less aware of the difference of the two terms,
sometimes using them as synonyms even in accident samples with all
kinds of collision types. This can result in significant
misinterpretations of the biomechanical and medical findings in
their study. Mechanisms of severe injuries have to be divided into
those with extensive intrusions, described by the EES, and into
those without intrusion but high inertial loading, caused by a high
delta-v. Several examples are shown where just ""looking
at the car photo'''' leads to an enormous error in
the judgement of the delta-v.
A large amount of instrumented crash tests has visualized the
theoretical calculations in practice; more such tests will be
carried out documenting the difference of collision speed, delta-v
and EES in various collision angles and overlap values, also in
pure side impact. Moreover the test results have been simulated by
mathematical accident reconstruction tools.