The Effect of Variable Seat Back Angles on Human Response to +Gz Impact Accelerations.
Interim rept. Jul 86-Apr 91,
ARMSTRONG LAB WRIGHT-PATTERSON AFB OH
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During 1986-1987, eighty-two human impact experiments were accomplished on a vertical deceleration tower to determine the influence of variable seat back angles on human dynamic response to short-duration acceleration applied in the x axis. Subjects were exposed to acceleration at a level of 10 G using a vertical deceleration tower. The seat back angle varied as follows 1 5 deg 5 deg aft of vertical, 2 0 deg vertical, 3 -5 deg 5 deg forward of vertical, and 4 -10 deg 10 deg forward of vertical. The resultant seat loads in the z-axis did not show statistically significant differences as the seat back angle was varied. Data showed a trend for head acceleration in the -x axis to increase and for head acceleration in the x axis to decrease as the seat back angle became more negative. This implies that cervical spine flexion increases as the seat back angle becomes more negative. This is supported by motion analysis using high-speed photography which indicated a trend for increased forward rotation of the head as the seat back angle became more negative. These experimental data will be used in the formulation of biodynamic models. Impact Tests, Vertical Deceleration, Cervical Spine, Biodynamics, HeadNeck Response, Seat Back Angle, Off-Axis Impact.