The seat transmissibility of an occupant-seat system: the influence of horizontal excitations with the additional vertical motion

Seat transmissibility is associated with both seating dynamics and biodynamics. The aim of this experiment was to investigate how seat transmissibilities are affected by the horizontal excitation variations as well as the presence of the vertical excitation. Twelve participants were evaluated for the seat transmissibilities during the horizontal random excitation at three amplitudes with and without additional vertical excitation. The primary resonant frequencies of the vertical cross-axis and horizontal in-line seat transmissibilities reduced with an increase in the horizontal excitation. The seat transmissibility acquired from single-axis excitation exhibited the same resonant behaviour as those obtained from dual-axis excitation. The nonlinearity of the seat transmissibility with dual-axis excitation suggests coupled modes are induced by the cross-axis effect.