Experimental study of the dynamic mass of a seated subject exposed to vibrations along the fore-and-aft axis in order to establish a model.

One seated subject was exposed to random vibration along the fore-and-aft axis. Acceleration and force in the X-direction were recorded to calculate his apparent mass and to investigate the effect of body posture and seat configuration on apparent mass. Five seat configurations were tested: flat rigid seat surface, flat rigid seat surface covered with 20 mm foam, driver seat cushion without backrest and Suspension, driver seat cushion with backrest and no suspension, driver seat with backrest and suspension. Three postures were also investigated, feet either directly supported on the shaker or on a footrest fixed to the seat. Hands were located on tights or on steering wheel. Backrest, initial position of the upper body, hands position are relevant parameters, to be taken into account for the development of a numerical model of a subject exposed to whole-body random vibration in the fore-and-aft direction.