Automotive Seating Foam: Subjective Dynamic Comfort Study 1999-01-0588
Many studies have been done to objectively measure car seat foam properties and correlate them to comfort performance. Typically, the vibration characteristics (namely transmissibility) of the foam cushion are measured. It has been generally accepted that low natural frequency equates to better comfort. However, no subjective studies have been done to verify that humans can feel the vibration differences that are measured. Also, the measured differences of the foam may not be detectable once the foam is built into a complete seat.
Three different foam formulations utilizing MDI (methylene diphenyl diisocyanate) and TDI (toluene diisocyanate) technology were evaluated for vibration characteristics. The foams were then submitted to subjective human testing and objective lab testing after being built into seats. The subjective testing was done using a typical ride and drive evaluation where people were interviewed about the comfort of the seat while driving over various road conditions. The objective testing was carried out with an anthropodynamic dummy placed onto the seat while undergoing various simulated road conditions. This study shows that when there was a difference in vibration transmissibility of foam cushions, it was not perceived by human test subjects or lab dummies sitting on completely built seats.