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Classifiers to Augment the CDC System to Distinguish the Role of Structure in a Frontal Impact Taxonomy
Abstract:
The purpose of the study was to distinguish the role of vehicle
structure in frontal impacts in published coded National Automotive
Sampling System (NASS-CDS) data. The criteria used: Collision
Deformation Classification (CDC) coding rules, crush profile
locator data and the projected location of longitudinal structural
members in models of vehicle class sizes used by NASS-CDS. Two
classifiers were developed to augment the CDC system. The
Coincidence classifier indicates the relationship between the
quadrant of the clock face the crash vector originates in and the
aspect of the end plane the center of damage is located. It has
three values: Linear (12 o'clock impacts) Consistent and
Variant ("oblique" Principal Directions of Force or
PDOFs). The second classifier indicates the number of longitudinal
members engaged: 0, 1 or 2.
NASS-CDS data for sample years 2005 to 2009 was filtered for
occupants involved in impacts with the highest ranked speed change
assigned to the front-end plane. The set excluded impacts assigned
a PDOF greater ± 50 degrees and small over-lap (SOI) type impacts.
A set of 12,165 raw records (4,655,471 weighted) for occupants in
wide type impacts that extending from the bumper to the belt line
or above was collected and subdivided into linear and oblique
categories.
1,910 raw records involved Consistent impacts; 75 (3.9%)
occupants (16,481 weighted or 3.6%) were in impacts involving 0
rails. 164 (8.6%) or 40,189 weighted (8.7%) involved 1 rail and
1,671 (87.5%) records or 405,022 weighted (87.7%) involved 2 rails.
160 raw occupant records involved Variant impacts, 2 (1.2%) or 73
occupants weighted (≻1%) involved 0 rails. 80 (50%) or 20,175
weighted (43.9%) involved 1 rail and 78 (48.8%) of the raw records
(25,682 weighted or 56%) involved 2 rails.
To evaluate the theory of the Coincidence classifier, a matrix
of impact configurations were submitted to NHTSA for simulation.
Impacts predicting head motion beyond the perimeter of the steering
wheel were deemed oblique. Twenty-one simulations with vectors of
10, 20 and 50 degrees resulted in eight predicted occupant
kinematics consistent with an "oblique" impact.