Seat pan angle optimization for vehicle ride comfort using finite element model of human spine

Ride comfort of the driver/occupant of a vehicle has been usually analyzed by multibody biodynamic models of human beings. Accurate modeling of critical segments of the human body, e.g. the spine requires these models to have a very high number of segments. The resultant increase in degrees of freedom makes these models difficult to analyze and not able to provide certain details such as seat pressure distribution, the effect of cushion shapes, material, etc. This work presents a finite element based model of a human being seated in a vehicle in which the spine has been modelled in 3-D. It consists of cervical to coccyx vertebrae, ligaments, and discs and has been validated against modal frequencies reported in the literature. It was then subjected to sinusoidal vertical RMS acceleration of 0.1 g for mimicking road induced vibration. The dynamic characteristics of the human body were studied in terms of the seat to head transmissibility and intervertebral disc pressure. The effect of the seat pan angle on these parameters was studied and it was established that the optimum angle should lie between 15 and 19 degrees. This work is expected to be followed up by more simulations of this nature to study other human body comfort and seat design related parameters leading to optimized seat designs for various ride conditions.