Vibrational Characterization of Various Polyurethane Foams Employed in Automotive Seating Applications

Abstract

As vehicle seat designs have moved from a spring/foam composite design to a foam/pan or deep foam design the vibrational characteristics of the foam has become increasingly important. It is now necessary to understand how to improve the vibrational properties of polyurethane foam to assure a comfortable ride and attenuation at the appropriate frequency ranges. It has been demonstrated via modeling foam vibrational characteristics that one can optimize the vibrational performance of foam by simply comparing foam peak frequency and peak transmissivity—these properties predict the foam transmissivity curve. Foam technologies included in this work were TDI HR, TDI hot cure and MDI HR systems. Data were presented which explored how vibrational properties correlated to foam IFD and ball rebound. Regression analysis data were also presented which demonstrated how foam formulation and processing variables could change foam vibrational characteristics. Generally, TDI chemistry provided the desired lower natural frequency response and was the least sensitive to processing variables. An understanding of these trends is the first step to assuring a quality ride for deep foam seating.