Visco-Elastic Polyurethane Foam As An Injury Mitigation Device In Military Aircraft Seating

Abstract. Energy-absorbing seats have become an important component of aircraft design, providing additional safety for occupants during crash impacts. Although the design of seat systems has not traditionally considered the cushion as an energy absorption device, some new aircraft incorporate cushions as an energy-absorption mechanism, using Visco-elastic Polyurethane (VEPU) foams. The literature indicates that VEPU cushions could potentially result in a significant reduction in impact force to the seat occupant, when compared to more conventional cushions. Vertical impact tests have been conducted on a drop test machine to determine the impact profile of cushions and their potential to reduce force transmitted to a seat occupant during a 2.0–8.2 m/s crash. Traditional basic seat foams and commercially available VEPU foams were used. The VEPU foams significantly reduced the impact loading as expected. The optimum density and stiffness of VEPU cushions depended on the level of maximum impact loading. While more work is required, a properly selected VEPU cushion of the same dimensions as current cushions used in existing aircraft seating is likely to provide significant crashworthiness improvement and also reduce occupant fatigue.