Seated Human Body Behavior Under Random Vibration

Contemporary vehicles have to satisfy high ride comfort criteria. In order to determine appropriate human body model in driving condition field and laboratory investigations on passenger cars have been performed. In field research, dominant vibrations loading of passenger was determined by variance analysis of experimental results. The highest loading is in vertical and the lowest is in lateral direction. These results were base for further laboratory investigations. Group of thirty volunteer subjects was tested. We examined the influence of broadband random vibrations on human body behavior by Seat To Head Transmissibility (STHT) function. The influence of vertical and fore and aft vibrations on occupants were examined separately. In addition to, the influence of multi directional vibration was investigated. Analysis of STHT results showed that in vertical direction seated human body has two or three peaks and two peaks in fore and aft direction under multi directional broadband random vibration. There was high coherency between signals in vertical and fore and aft, directions on the same measuring place. Human behavior under multi directional random vibrations can not be approximated by simple superposition of one directional vibration results. Also, hand position had not influence on STHT results and model of passenger was considered. Obtained results were base for definition and parameter identification of appropriate biodynamic human model in driving position. Two-dimensional non-linear model was developed. Suggested model showed good corresponding with experimental results.