Sitting comfort of automotive seats includes two aspects: dynamic comfort and static comfort. In the first part of this paper, the effects of dynamic parameters of seat (i.e. inherent frequency and damping ratio) on frequency response characteristic of "human-seat" system are studied by means of a 3-freedom-degree model which can reflect the frequency response characteristics of "human-seat" system with a real subject sitting on the seat. The results show that the inherent frequency can be selected within a range of 4 - 9Hz. When damping ratio is low, the changing of the inherent frequency can adjust effectively the frequency response characteristic of "human-seat" system. Thus it is an effective way to obtain the best dynamic comfort of seat under random vibration inputs of different frequency structures. Property of pressure distribution at the interface between human body and seat cushion is investigated in the second part of this paper. With a self-developed measuring system, 4 characteristic parameters of body pressure distribution, i.e. the maximum pressure, roll stability moment, thigh pressure sum and longitudinal pressure distribution curve are obtained. A subjective evaluation test is conducted to obtain comfort assessment of seats. By processing data of subjective evaluation test with fuzzy mathematics, combining the results with objective parameters, a procedure for classifying of seat comfort through measuring of body pressure distribution is given. (A)
Abstract