Abstract:
This research investigated viscous injury from vertical impact loading to determine if it
is critical to survivability of aircraft accidents. A unique database was built from
autopsy reports and accident investigations combining injury data with the vehicle
impact data. Computer models were created and used to assess injury potential.
Common design limits and actual crash data from full scale research experiments were
used as inputs. The results were analyzed according to published injury thresholds and
compared with real accident autopsies to determine the validity of the hypothesis.
Heart and Aortic Injury (HAI) has been considered a critical survivability factor
through out the history of mechanized transportation. The mechanisms of HAI in the
aircraft environment were never well characterized. Automotive research identified
important HAI injury mechanisms related to the forward and lateral impact vectors.
This research investigated the vertical impact vector. A model was developed to
evaluate the biomechanical response of a simplified visco-elastic system, and
incorporated into a system model which included the occupant and aircraft seat. This
approach was similar to the development of spine injury criteria and provided the
advantage of a macro level evaluation of the injury thresholds and assessment of the
criticality in survivable accidents.
Evaluations of real accidents sustaining HAI characterized a range of impact severity
and approximate boundaries for survivability with HAI and internal organ injury.
Viscous injury potential from vertical impact was found to be less critical than potential
spine injury. Detailed analysis of HAI documented in autopsy reports and the
corresponding accident investigations found that HAI was associated with cockpit
environmental factors rather than inertial displacement mechanisms. Vertical
displacement of the heart due to inertial loads is not a critical factor in survivable
accidents given current aircraft technology. Inertial loading to the heart and aorta is a
contributory factor for viscous injuries in aircraft accidents.
