Measurement of dynamic support properties for comfort analysis of vehicle passenger seats under road excitation condition

Abstract

This paper presents a mathematical model that was developed to represent the apparent mass of the seated human body. The model applies the concept of coupling stiffness. An analysis was performed where the seat was divided into four areas for a deeper understanding. The distributed dynamic stiffness, coupling stiffness, and loss factor of the seats were measured with a dummy that was built based on the model. Six seats without backrests were exposed to random vibrations from a shaker in the laboratory. An on-road test of 12 cars was conducted at the testing ground of HD Motors. The calculated stiffness and loss factor characteristics of specific locations of the seats were visualized in bar charts for comparison. A modal analysis was conducted on the human lower body interacting with the seat. The pitching and rolling motions of the lower body in accordance with the resonance frequencies of the transfer functions were determined. The variation in Seat Effective Amplitude Transmissibility (SEAT) values depending on the stability of different postures was identified. Because of the model’s ability to specify the human-seat interface from the division of the seat into four individual areas, it was able to verify the difference in frequency responses between the buttock and thigh parts.