Head Flail Corridors From Sled Impact Acceleration Tests for Use in Occupant-Centric Vehicle Design

In aircraft crashes, injuries to the head and upper torso are frequently reported, with head injury reported most frequently of all body regions. Because preventing flail of the head and body is of utmost importance for occupant survival, the Aircraft Crash Survival Design Guide (ACSDG), the guide to crashworthy aircraft design, published flail envelopes. However, the ACSDG flail envelopes are based on a single test with an anthropomorphic test device subjected to a frontal acceleration. In this article, human research volunteer (HRV) response data are used to calculate head flail corridors and evaluate the ACSDG flail envelopes.

Data from HRV sled tests were obtained from the historical Naval Biodynamics Laboratory collection of the Biodynamics Data Resource. Digitized high-speed film for each test was tracked and processed to represent the head flail response in a format amenable to corridor development. Time-based and position-based head flail corridors were developed for groups of exposure-matched tests and then compared to the ACSDG flail envelopes.

A collection of 714 HRV sled tests conducted in six different impact directions ranging from 3 to 15 g was used to develop time-based and position-based head flail corridors for 39 match groups. The ACSDG vertical limit and anteroposterior limit and curve were not exceeded by the flail corridors, but the lateral limit and curve were exceeded by 4.6 cm to 15.8 cm.

The flail corridors provide a useful baseline for representing the well-restrained occupant response at lower, non-injurious exposure levels and across multiple impact directions. Under these conditions, the ACSDG lateral limit and curve are not adequate. At higher exposure levels or with modified restraints, seating, or equipment, the ACSDG vertical limit and anteroposterior limit and curves may also be inadequate.