Abstract
To interpret the influence of whole-body vibration (WBV) on a seated human body, its vibration characteristics need to be clarified. Several previous studies have shown that differences in seated postures can change vibration characteristics such as the resonance frequency and the resonance amplitude of seat-to-head transmissibility and driving-point apparent mass. However, these studies did not fully express the seated postures of their subjects. Although the evaluation of human exposure to WBV is specified by ISO 2631, the seated postures for experiments are not specified in an ISO standard. To make good use of the results of human vibration experiments, a technical report on the description of seated postures exposed to WBV was published in 2012 and is still being discussed. In this study, we have measured seated postures in vibration experiments and investigated the relation between these postures and the resonance frequencies of transmissibility and apparent mass. A vertical random vibration of frequency 2-30 Hz was used in the experiment. The experiments were performed with two seated postures, an upright posture and a relaxed posture. The performance of a single regression analysis and a multiple regression analysis suggested that lumbar curvature is related to these resonance frequencies.
