THE EFFECTS OF VARIABLE HELMET WEIGHT AND SUBJECT BRACING ON NECK LOADING DURING FRONTAL -GX IMPACT

摘要

Helmet-mounted systems (HMS), such as night vision goggles and helmet-mounted displays, are designed to enhance pilot performance. Using HMS, however, may also affect pilot safety by increasing the potential for neck injury during ejection due to the increase in dynamic forces generated in the cervical spine as a result of the change in helmet inertial properties. Pilot bracing techniques may also have an effect on ejection injury risk by allowing some of the neck forces to be off-loaded during the acceleration impact phases. A series of tests were conducted on the AFRL/HEPA Horizontal Impulse Accelerator (HIA) using human subjects to investigate the effects of helmet inertial properties and bracing techniques on human response to short-duration frontal impacts of variable magnitude. Head accelerations were measured and neck loads and moments were calculated to compare the head and neck responses using helmets of varying weight. Headrest loads were recorded to monitor and evaluate subject bracing. The neck loads and helmet weights were also extrapolated to higher levels in order to estimate injury thresholds for pilots wearing even heavier helmets at maximum seat accelerations. The results of this study will be used to establish head/neck injury criteria for helmet-mounted systems and to improve bracing techniques to minimize pilot injury during ejections.