Two vibration modes of a human body sitting on a car seat-the relationship between riding discomfort affected by the material properties of the seat cushion and the two vibration modes

Abstract

The relationship between the properties of flexible polyurethane foam composing seat cushions for standard cars and the riding discomfort evaluated by subjects who sat on the seat were investigated. The properties of five kinds of polyurethane foam were measured using the DMA to define dynamical properties. Riding discomfort was subjectively evaluated by 17 subjects at four frequencies, and the correlation coefficients between the material properties and riding discomfort were analyzed. The results suggested that there were two relationships between material properties and riding discomfort, and that these relationships strongly relied on frequency. Furthermore, a digital human model was created to confirm the influence of frequency on these relationships, which suggested that the relationships affected sensitivity by the change in the vibration mode of the human body-seat vibration system. © Springer-Verlag Berlin Heidelberg 2007.