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Min Li, Zhihui Wu, Bob Tackett, Jilei Zhang


Human subjects were hired to sit on an instrumented chair to measure impact loading as a function of time. These loads were compared with testing loads that are used in the ANSI/BIFMA X5.4 and X5.1 Seat drop and seat durability loading test regimens. Factors that were investigated experimentally on impact loading were standing-to-sitting ingress1 motion, seat foundation type, seat height, as well as sandbag weight and drop height. Center of seat deflection, caused by human subjects and sandbags, were recorded as a function of time. Experimental results from human subjects’ sitting tests concluded that maximum sitting forces averaged 100% and 247% with respect to a participant’s body weight for normal and maximum sitting impact forces. The seat deflection speeds for normal sitting was 16.3 cm/s and varied from 71 to 84 cm/s for hard sitting. Sandbag free drop experimental results indicated that drop height had a significant effect on maximum impact forces on the seat foundations. Maximum impact drop forces increased as sandbag weight increased, but the significance was dependent on the seat foundation type. The panel-foam seat foundation had the lowest impact force among three seat foundations evaluated. The spring-foam seat foundation resulted in significantly higher impact forces than the panel-only seat foundation if the sandbag drop height was less than 13 mm, but as the drop height increased to 30 mm, the significance became less. The impact force on a panel-only seat foundation became significantly higher than the spring-foam foundation as the drop height increased to 50 mm.





Sitting force, seat load, impact load, seat foundation, normal sitting-down, hard sitting-down

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