J2320105 多軸入力を受ける全身振動特性の着座姿勢による変化

抄録

It is important to investigate the effects on a seated human body exposed to whole-body vibration. We have shown the effects on a human body based on the changes in the seated postures exposed to vertical excitation. We, however, have not dealt with fore-and-aft or lateral excitation. Accordingly, the major objective of this study is to investigate the relationship between the vibration characteristics on a seated human body and the seated postures exposed to fore-and-aft, lateral and vertical excitations, respectively. Ten seated male subjects were measured at their heads in fore-and-aft, lateral, vertical, and roll and pitch directions, in terms of seat-to-head transmissibility and driving-point apparent mass, under random vibration excitations in the three directions. The random fore-and-aft and lateral excitations were in the range of 1-20 Hz, and the vertical excitation was in the range of 1-30 Hz. Each magnitude of the random excitations was 1.0 m/s^2 rms. Three different seated postures were examined: upright, relaxed, and the intermediate thereof. As a result, the resonance frequencies of 2-3 Hz and 10-2 Hz were obtained for for-and-aft excitation and lateral excitation, respectively. The results also showed that, under vertical excitation, the resonance points vary depending on the seated postures, while they do not under fore-and-aft lateral excitations. Moreover, the transmissibility of the pitch direction durng vertical and fore-and-aft excitation could be considered as being coupled vibration.