Prediction of Static Settling Point in a Seat Occupant System
Published June 18, 2002 by Verlag Des Verein Deutscher Ingenieure GmbH in Germany
The H-point location of a car seat occupant is strongly governed by the quasi-static behavior of polyurethane foam. Foam is a complex material with nonlinear stiffness and viscoelastic properties (creep). Foam properties are affected by compression level, excitation amplitude, temperature and humidity. Models of foam behavior are incorporated into a 2D model of a seat-occupant system. This multi-degree-of-freedom planar model predicts x, z and ϑ motions of a seat-occupant system consisting of interconnected masses, nonlinear springs and dampers. A graphical user interface is developed to visualize the settling of the occupant in the seat. A detailed study of the effects of changing foam stiffness and friction at occupant seat interface is included. The models described can also be used to predict the dynamic response of seat-occupant systems if the parameters characterizing the foam are adjusted appropriately.