Computational Assessment of Positional Sensitivity to Injury in Spacecraft Occupants

Abstract

Spacecraft occupants are susceptible to injury from sudden loads, such as those experienced during landing. Most injury biomechanics investigations assume perfect seated posture and consistent seated position. However, this assumption is unrealistic, as offsets from these presumed postures and placements are likely during impacts. In this computational study, the Global Human Body Model Consortium’s simplified 5^thpercentile female and 50^th and 95^th-percentile male anthropometric models were seated and restrained in three positions: nominal, (“perfect” posture and placement); and 10 millimeters and 25.4 millimeters forward of the seatback. Biodynamic responses to simulations involving vertical accelerations were analyzed for positional sensitivity. The 5^th-percentile female was most susceptible to neck injury due to compressive forces. In 50^th and 95^th-percentile males, upper spinal intervertebral forces were positively correlated to seated position (increasing 13% for 25.4mm forward offset). Analysis of head excursions and knee splay data indicates potential whiplash and the need for conformal seating, respectively.