Abstract

The vibration attenuation performance of suspension seats employed in heavy vehicles are influenced by energy dissipation property of the seated body. Owing to complexities associated with biodynamic response behavior of the human body, the performance assessments of suspension seats are invariably accomplished through laboratory or field experimentation. Such laboratory experiments involve certain safety and ethical concerns, while field measurements yield difficulties in interpretation of the results due to lack of controlled conditions. In this dissertation, two prototype anthropodynamic manikins, designed to replace human subjects in assessments of seat, are evaluated through laboratory experiments and analyses of the biodynamic responses. The apparent mass (APMS) responses of manikins are characterized under different levels of vibration excitations and three body masses (55 kg, 75 kg and 98 kg). The measured responses are compared with the standardized values to assess the APMS prediction abilities of the manikins. The results suggest the need for deriving more reliable APMS responses of seated humans of particular masses. The applicability of the manikins for seating dynamics is then assessed for a range of seats and vibration spectra of different vehicles. The seat effective acceleration transmissibility (S.E.A.T) of five different seats are measured using human subjects, equivalent inert mass and the prototype manikins. The results suggest that equivalent inert mass could provide reasonably good prediction of seat performance, when excitations dominate in the low frequency range. Under high frequency excitations, the inert mass yields poor estimate of the seat-human system performance, while the manikins provide better estimations. The need for tuning of the manikins was identified to improve their biodynamic response prediction abilities. An analytical model of one of the manikin was thus formulated and analyzed to perform the necessary design refinements. System identification technique was applied to derive uncertain parameters of the model so as to satisfy the measured APMS responses for three body masses. Additional parameter identification was performed to realize desirable parameters that would satisfy the standardized biodynamic response. The results suggested that only minor refinements of the prototype would be needed to enhance the biodynamic response prediction ability of the manikin, which may translate into improved applicability of the manikin for assessment of suspension seats.