Lower limb contribution to the dynamic response of the seated man

Effects of elastic seats on seated body apparent mass responses to vertical whole body vibration

“…The interface pressure on an elastic seat is more evenly distributed over a larger effective area than on a rigid seat (Wu, Rakheja, and Boileau 1999;Akgunduz, Rakheja, and Tarczay 2014), while the peak contact pressure on a soft seat is substantially lower compared with that on a rigid seat. Furthermore, an elastic seat causes considerably different pelvic orientation than a rigid seat, while it encourages greater pelvic rotation and relative motions across the legs, which are absent with a rigid seat (Lemerle and Boulanger 2006). The measured AM responses, reported in the two studies, however, differed substantially, partly due to differences in the excitation conditions and the measurement systems.…”

“…The differences in the pelvis rotations with different seats might be one of the contributory factors to observed variations in the AM magnitudes around the secondary resonance frequency. Lemerle and Boulanger (2006) reported that pelvis rotations have no significant effect on the primary resonance frequencies. The observed variations in the primary resonance frequencies of the body (Table 3) are likely due to differences in visco-elastic properties and thus the vibration transmissibility characteristics of the seats.…”

Whole-body vibration biodynamics - a critical review: I. Experimental biodynamics

“…In a vehicular environment, the lower limbs would encounter relative movements due to deflections of suspension at the seat and/or seat cushion, which may cause increased pitch rotation of the pelvis. It was shown that lower limb motion reduces the peak AM and increases the corresponding frequency (Lemerle and Boulanger, 2006). The effect may be related to increased pelvis rotation, while seated on a free vertical suspension.…”