Assessment of Memory Cushions in Aircraft Seating for Injury Mitigation through Dynamic Impact Test

Dynamic impact tests were conducted to assess the effectiveness of the Visco-Elastic Polyurethane (VEPU) memory foam seat cushions in mitigating impact to the occupant during an aircraft crash. A FAA specification Hybrid III crash dummy and seats with and without a stroke energy absorbing mechanism were used in the tests. Polyurethane foam (PU) cushions were also tested for comparison. The results with the rigid seat indicated that with 8.3 m/s impact, lumbar spine injury would occur. VEPU cushions reduced the lumbar force by up to 34%. With an impact speed of 6m/s, a VEPU cushion mitigated the impact to the tolerable level, whilst injury would still occur with the PU cushions. The results with the energy absorbing seats showed that with 8.3 m/s impact speed, the seat with over 125 mm (5 inch) stroke length is able to reduce the impact load below the injury threshold. A relatively softer VEPU cushion reduced the lumbar force by over 15% compared with the PU cushions. With a stoke length of 75 mm (3 inch), bottom-out occurred and occupant lumbar spine injury would occur. A relatively higher stiffness VEPU cushion reduced lumbar force by around 20%.