Nonlinear behavior of sitting humans under increasing gravity.
To determine the nonlinear properties of the upright sitting human body, driving-point impedance as well as the transmissibility from seat to head were determined under increased gravity on a centrifuge. Under this condition a shift of resonances to higher frequencies was observed. At the same time the transmissibility increased distinctly. To explain this behaviour with a model, a nonlinear multi-degree-of freedom model of the upright sitting body was calculated. It elements represent identifiable body parts. Protective measures for normal gravity conditions, as well as for sustained acceleration, were derived.
D000054:Acceleration; D000328:Adult; D005260:Female; D006112:Gravitation; D006801:Humans; D008297:Male; D008954:Models, Biological; D011187:Posture; D014732:Vibration