A Simple Mathematical Model of a Vehicle with Seat and Occupant for Studying the Effect of Vehicle Dynamic Parameters on Ride Comfort

A mathematical model of a vehicle dynamic system capable of predicting ride comfort can be a useful tool for vehicle design and development engineers at the concept design stage. The aim of this study was to develop a simple mathematical model of a vehicle with seat and occupant to investigate how vehicle dynamic parameters affect the vibration transmission and ride quality. A 13 degrees-offreedom mathematical model including tyre, suspension, vehicle body, engine and mounting, seat and occupant was developed and calibrated with measured data. Acceleration transfer functions from road input to the seat and occupant were calculated. Sensitivity analyses with a Design of Experiment method was conducted to identify the vehicle parameters that were most influential on the ride quality in terms of the frequency weighted acceleration r.m.s. values at the seat rail and the seat-occupant interface under random vibration input in the vertical direction. Results showed that the seat vibration was most sensitive to the damping and stiffness of the rear suspension, the stiffness of the tyre and the seat. The location of the engine block also has significant effect on the ride vibration. The proposed model can be used by engineers to quickly assess how ride comfort of a vehicle is affected by the design parameters.