Modeling and analysis of a train seat with occupant exposed to combined lateral, vertical and roll vibration

Abstract

Abstract Considering the ride vibration of rail vehicles, a double-unit train seat model under exposure to combined lateral, vertical and roll vibrations was developed using multi-body dynamic modelling technique. Two coupled seat-occupant models, i.e. the double-unit seat with one occupant and two occupants, respectively, were then developed by integrating the seat model with a seated human model developed in a previous study. The corresponding seat transmissibilities measured in the laboratory experiment were used to calibrate the seat and seat-occupant models. The seat transmissibilities calculated with the models showed good agreement with the measured transmissibilities. Modal analyses with the models of the seat, human body, and seat-occupant systems, respectively, were carried out to find out the association between the resonances in the seat transmissibilities of the seat-occupant systems and the modal properties of the human body or the seat, and reveal the variation of the modal properties arising from the coupling between the seat and human body. The principal resonance around 5 Hz in the vertical transmissibility at the seat pan was found to arise from a vertical mode of the entire human body. A slight reduction of the modal frequency and modal damping of this mode was caused by the coupling between the seat and human body. It was further disclosed that the two resonances around 15 and 27 Hz in the seat transmissibilities resulted from two seat modes with close frequencies, respectively. The mode shape of the former (about 15 Hz) featured the in-phase motions of the two seat pans and backrests in lateral and roll directions, while that of the latter (about 27 Hz) was associated with the motions of the two backrests in lateral and roll directions. The results also showed that human bodies tended to increase the modal damping of the two seat modes.