Nonlinear Multi-Body Dynamics of Seat-Occupant Systems Using Experimentally Identified Viscoelastic Models of Polyurethne Foam

Most modern car seats are full-foam and thus the H-point location depends on quasi-static behavior of foam. In this work, planar multi-degree-of-freedom models of seat-occupant systems that incorporate nonlinear viscoelastic behavior of polyurethane foam are developed. The foam force is modeled as an additive sum of nonlinear elastic and linear viscoelastic effects and the model parameters are identified using a parameter identification technique. A possible model for seat-occupant interface is introduced. The resulting nonlinear integro-differential-algebraic model is used to determine the H-point for the system.