1996-02-01

Real Time Dynamic Comfort and Performance Factors of Polyurethane Foam in Automotive Seating 960509

Polyurethane foam continues today as the premier cushioning material utilized in automotive seating applications. In seating design, most foam properties specified by the design engineer in establishing foam properties currently are based upon static test methods. The in-service mode of an automotive seat, however, is dynamic rather than static. Therefore, the overlooked real time dynamic properties are of greater importance for the comfort performance of a seat than such static properties as Indentation Force Deflection (IFD) or density. Unfortunately, there are no widely accepted test methods for dynamically characterizing automotive seating foam. Correlation of real time dynamic properties to comfort could minimize the need for expensive, time consuming and subjective road testing. The purpose of this paper is to propose some potential dynamic characterization techniques for automotive seating foam.
Different polyurethane technologies, all adaptable to the manufacture of automotive seating are shown to exhibit quite different real time dynamic properties not predictable from static tests. In this paper, changes in dynamic modulus as a function of flex history are monitored in real time and related to the specific polyurethane technology employed. Likewise, dynamic hysteresis and changes therein are studied in real time. Vibrational transmissivity characteristics are explored by means of a constant g frequency sweep method. The adaptability of polyurethane foam to provide varied dynamic properties gives the automotive seat designer the ability to specify the ideal cushioning material to yield the maximum comfort to a specific design.

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