Mechanical Impedance of Supine Humans under Sustained Acceleration
DEUTSCHE FORSCHUNGS- UND VERSUCHSANSTALT FUER LUFT- UND RAUMFAHRT E V BONN-BAD GODESBERG (GERMANY F R)
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Measurements of the mechanical impedance of the supine human body were conducted to investigate the nonlinearities of the body system. A hydraulically driven shake table was installed on a centrifuge. Transmitted force and the acceleration of the platform, on which the subjects were lying, were recorded in the frequency range of 2Hz-20Hz. Sinusodial acceleration amplitude was held constant at 0.5g. The impedance and phase results show that sustained acceleration up to 5Gx stiffens the human body with increasing Gx and shifts the resonance frequency from6Hz under normal gravity to 8Hz under 2Gx and further up to 11Hz, 13Hz and 15 Hz under 3Gx, 4Gx and 5Gx respectively. The modulus of impedance grows with centrifuge acceleration. These results show that the human body behaves nonlinearly in an extreme dynamic environment.
- Stress Physiology