Abstract

The seated occupant responses to whole body vibration have been widely investigated, mostly under vertical vibration stimuli. The vibration environment of heavy road and off-road vehicles also comprises significant components of horizontal vibration, with magnitudes either comparable to or higher than those of the vertical vibration. It is thus desirable to investigate the seated body responses to horizontal vibration. This study concerns with characterization of the biodynamic responses in terms of apparent mass and the power absorbed by seated human occupants exposed to longitudinal and lateral vibration in the 0.5-10 Hz frequency range under automotive seating postures. The measured data revealed consistent trends in view of the factors considered, namely, the posture (back supported or unsupported), as well as the direction, magnitude, type and frequency of vibration. The results suggest strong influence of the acceleration magnitude, the back support condition and the type of whole-body vibration. The peak magnitudes of APMS and absorbed power revealed good correlation with the body mass, suggesting increased energy absorption by heavier subjects. The vibration energy absorption properties of the seated body in the low frequency range revealed highest correlation with the anthropometric factors and the magnitude of the stimulus. The data is expected to serve as a basis for developing mechanical equivalent models of the occupant for seating dynamics applications, and to enhance knowledge on the human behaviour under exposure to horizontal vibration.