Modelling and analysis of coupled vibration of human body in the sagittal and coronal planes exposed to vertical, lateral and roll vibrations and the comparison with modal test

Abstract

To study the coupled vibration of the seated human body in the sagittal plane and coronal plane exposed to lateral, vertical and roll excitations, a seated human body model consisting of abdomen, pelvis, two thighs, upper torso (including the shoulders, thorax, arms), and head (including neck) was proposed. The model was calibrated with the apparent masses measured in 0.5–20 Hz and proved to be applicable for subjects of different weights and heights and different excitation magnitudes in combined lateral, vertical and roll directions. This model was also potentially suitable for different backrest inclinations. Three modes of the human body associated with the resonances in the measured apparent masses were observed by means of modal analysis. The first and second modes with modal frequencies of 1.16 and 2.53 Hz, respectively, featured the vibration of the human body in the coronal plane. The former was dominated by the lateral and roll vibrations of the upper torso and head, while the latter by the lateral whole-body vibration accompanied by roll of the upper torso and head. The third mode with a modal frequency of 5.28 Hz featured the vibration of the human body in the sagittal plane. This mode exhibited a combination of the vertical vibration of the entire body and a bending motion of the upper body arising from the pitch of pelvis. These three modes showed good consistency with those identified in the modal test. The vibration coupling between the sagittal plane and coronal plane associated with these three modes was not significant. This model can be used to calculate the ride vibration and comfort of passengers in rail vehicles.