A VIBRATION MODEL OF OPEN CELLED POLYURETHANE FOAM AUTOMOTIVE SEAT CUSHIONS

A mechanistic model of a seat cushion is developed. The work relates t he kinematic motion of the seat to the geometric and constitutive prop erties of the cellular foam used in the seat. The model includes the i nfluence of pneumatic damping caused by friction between the gas withi n the open-celled foam and matrix polymer. A continuous shape function is introduced to characterize the piecewise continuous stress-strain characteristic of flexible open-celled foam. After some simplification , a non-linear dynamic automotive seat cushion model is derived, which relies explicitly on the constitutive properties of polyurethane foam s and on the geometry of the seat cushion. Experimental and analytical models of the two automotive seats are compared to verify the model. The comparisons indicate that the new model is able to predict the dyn amic performance of an automotive seat cushion with fidelity. (C) 1998 Academic Press.