Abstract

The occupant-seat contact properties are investigated through analyses of interface pressure using explicit dynamic finite element (FE) simulations. A finite-element analysis model of a seat is developed in the LS-DYNA platform, where the material model is formulated on the basis of reported stress-strain properties of different polyurethane materials. The seat model is coupled with the finite-element models of the occupant based on the well-established frontal crash anthropomorphic test devices (ATD). The validity of the seat model is initially illustrated through simulation of a compression test model, which suggested that the hyperelastic stress-strain responses of the PUF materials can be reliably estimated using the explicit dynamic finite element platform, LS-DYNA®. The validity of the coupled seat-ATD model is also illustrated through comparisons of the contact pressure and contact area responses with the reported measured data. It is shown that the coupled occupant-seat finite element model can provide reasonable good predictions of the interface pressure and contact area, which have been correlated with occupant’s sensation of comfort. This suggested that FE models of ATD can be effectively used for predicting occupant-seat contact pressure and thus the comfort performance of seats for different body sizes, ranging from 5th percentile female to 50th and 95th percentile male population. The simulation results are obtained to illustrate significance of various factors affecting the contact pressure distribution, namely the material property, material thickness, dimensions of ATD, occupant load distribution, seat geometry and design of side wings. The contact pressure distribution and contact area responses of different design configurations of the seat are subsequently obtained and discussed so as to build guidance towards designs of seats with reduced contact pressure distributions. It is shown that the side wings constitute an additional load path and can contribute significantly in distributing the occupant load over a wider contact area and thereby limit the peak contact pressure.