• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.04a
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• pp.218-223
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• 2011

Seated human subjects have been exposed to vertical vibration so as to investigate six-axis biodynamic response. Sixteen males were exposed to random vertical vibration in the frequency range(3~40Hz) at one vibration magnitude(0.224m/$s^2$ r.m.s.). Forces were measured in the vertical, fore-and-aft, lateral, roll, pitch and yaw direction on the seat. The median of cross-axis apparent mass magnitude in the fore-and-aft direction could reach up to 20% of the apparent mass magnitude at resonance frequency. And the median of apparent eccentric mass magnitude in the roll direction could reach up to 15% of the apparent eccentric mass magnitude in the pitch direction at resonance frequency. But cross-axis apparent mass in the lateral direction and apparent eccentric mass in the yaw direction showed very small.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.10
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• pp.897-904
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• 2011

When whole-body is exposed to vertical vibration, asymmetry shape of human body affects the response on the translational(fore-aft, lateral, vertical) and rotational(roll, pitch, yaw) motion. While the translational motion has been studied with various titles, it has been rare to study the rotational motion of human body exposed to vertical excitation because of lack of experimental equipment. This study was performed by using a 6-axis force plate installing strain gage type sensors for the rotational response. Sixteen male subjects were exposed to vertical vibration on rigid seat in order to investigate apparent mass of three translational motion and apparent eccentric mass of three rotational motion. Random signal was generated to make excitation vibration which was on an effective frequency range of 3~40 Hz, and magnitude of 0.224 m/$s^2$ r.m.s. The frequency range and magnitude used was selected for the vibration of passenger vehicle on idling condition. As the result, cross-axis apparent masses of fore-and-aft and lateral direction were not significant showing 20 % and 3 % of vertical apparent mass relatively. And apparent eccentric mass of pitch motion was dominant when compared to that of roll and yaw motion, which is reasoned by asymmetry direction of human body sitting on a seat.