VALIDATION OF A NONLINEAR AUTOMOTIVE SEAT CUSHION VIBRATION MODEL

A low-order, lumped parameter model is proposed to describe the vertic al vibration compliance of an automotive seat. The model includes nonl inear stiffness and damping effects that mimic the properties exhibite d by open cell foams that are commonly used in the construction of an automotive seat cushion. A shaped sandbag was positioned on a seat cus hion and vibrated to obtain test data. White noise acceleration with a mplitude ranging from 0.05 g rms to 0.45 g rms in increments of 0.05 g rms was used to excite the seat track. A luxury car seat and a sports car seat were tested and a nonlinear seat model was identified that p redicts the actual test data with fidelity. The paper demonstrates tha t once a family of model parameters is identified for a particular sea t, then the model can be used for a wide spectrum of seat track inputs . Additional experiments also verified that when the sandbag mass was increased by as much as 50%, the predicted response using the proposed model was in agreement with the measured response. Finally, the paper reports the result of an experiment using a human subject on a seat c ushion. A simulation using the new cushion model and an ISO vibration model of a seated human produced response data that was very similar t o the actual test data.