Vehicle Dynamics Simulation Correlation: Impact of Flexible Tyre and Flexible Frame in Comfort Prediction of Two Wheelers Motorcycles and Scooters 2024-26-0053

For any two wheeler vehicle development, rider and pillion comfort while driving the vehicles over different kinds of road perturbations holds high importance.

Designing a vehicle for comfort starts at the very beginning of its layout definition through vehicle geometric parameters, key hardpoints, mass-inertia distribution of subsystems and suspension characteristics. There is a need for highly reliable simulation models for comfort predictions as any change in layout during subsequent design stages is a very costly affair.

Accurately predicting comfort using a full vehicle model is a challenging task though as it depends on how realistic the Simulation Model is to that of actual vehicle. While suspension stiffness and damping characteristics remain critical parameters for the comfort, selection of tyres are known to hold equal importance in vehicle comfort. The details to which the tyres are captured in the simulation model and the formulation of tyre interaction with roads in a dynamic condition govern the dynamic forces going on the vehicle and hence decide the accuracy of comfort predictions as well.

More often conventionally used tire models and rigid body representation of frame are used in simulation models and don't result in good correlation with test data primarily because of the tire formulation, tire-road interaction and missing dynamics behavior of the frame itself. This paper talks about stage wise incorporation of a Flexible Tire and Flexible Frame in the simulation model and successive improvements in correlation with test data and the weightage of these changes in correlation improvement. The final simulation model is correlated with a physical test on a Prototype Vehicle where the vehicle has been driven over various road obstacles and the same has been simulated in the multi body simulation model. Various parameters like suspension displacements and accelerations are captured for establishing the correlation.