Differences in Dynamic Performance of Molded Polyurethane Foam as a Function of Pad Thickness and Supported Load

摘要

Comfort and durability have evolved into essential performancl requirements for the polyurethane foam used in automotive seating. A great va riety of tests have been developed in an attempt to measure and predict thesl properties, both for the foam and the assembled seat. However, the results fron these various tests can be quite different depending on the test conditions em ployed. Furthermore, most tests measure comfort properties at some standarc deflection, or pressure, which is nominally designed to represent the averagj population that will be riding on the seat. Missing from these tests is a recognition that foam comfort properties are no the same at all deflections:, and thus performance and perceived comfort wil change as a result of the size and shape of the person riding the seat. This re search presents information demonstrating the dependence of comfort proper ties, such as vibrational transmissivity and quasi-static hysteresis, on foan thickness and foam chemistry .In addition, the effect of pressure is demon strated using various masses for the transmissivity testing. This work will be an alyzed and discussed from the perspective that comfort properties may need tt be defined relative to the sitting pressure of the person riding on the vehicle seat