Effect of Seat Cushion Stiffness on Human Comfort

Human body encounters different types of vibration conditions while traveling, performing activities, driving, playing, etc. that results in discomfort and becomes a necessity to work in this domain. In this current study, harmonic analysis has been performed while applying a vibration in a vertical direction while human subjects sitting in sitting posture with backrest support on automotive seats. A 4-layered human subject CAD model of mass 76 kg has been developed to resemble with the realistic properties of human subject that includes shape with proper dimensions and biodynamic properties of bone, organs, muscle, and skin. For cushion material of seat Polyurethane foam has been used with its stiffness and damping properties. The study has been performed on human subject sitting on a seat cushion with varying thickness of fixed backrest at angle of 0° and excited with magnitude of 1.0 m/s2 in the frequency range 0–20 Hz. The seat-to-head transmissibility (STHT) has been evaluated using FEM and found that the maximum value of transmissibility effect is 3.12 at frequency of 6 Hz; but then decreases due to stiffness and damping of the cushion material of seat and backrest. It has been found from the current study that seat cushion has good vibration absorbing properties due to which there observed a less effect of vibration at more value of cushion thickness and also, it has been analyzed that the backrest cushion can also result in improving the human body ride comfort.