Investigation of the effect of safety belt on the seat transmissibility

Seat transmissibility is used to evaluate the vibration attenuation performance of seats. Because the seat and the driver interact with each other, the seat transmissibility is affected by the dynamic characteristics of the driver. The constraint on the movement of the driver caused by the safety belt results in the change of the seat-driver dynamics and the seat transmissibility. Vibration accelerations were measured on the seat cushion and at the seat base on a medium size wheel loader when the driver wore a lap belt or a four-point seat harness. The seat effective amplitude transmissibility value and the seat transmissibility derived from the cross spectral density method were analysed to investigate the effect of safety belt on the seat transmissibility. Two multi-body models of the seat-driver system were built in MATLAB and their parameters were identified in cases where the driver wore the lap belt or the four-point seat harness. Based on the analysis of these parameters, the way how the safety belt affects the seat-driver dynamics and the seat transmissibility is studied.