Effect of tyre modelling on tractor ride vibration predictions

A new tyre model for use in off-road vehicle ride vibration studies is proposed. It represents, in a way that is different from previous models, the mechanism by which tyres generate forces in the longitudinal and lateral directions. It was incorporated in a three dimensional tractor model and then tested by comparing predicted vibration results with those measured for ten tractors over a range of speeds on a known surface. Agreement between measured and predicted results, which has been notoriously poor using previous tyre models, was significantly improved using the proposed model. The major improvements were in the predictions of longitudinal and lateral tractor vibration levels. Though further detailed comparisons await completion, it is already clear that the proposed model represents a significant advance in tractor ride vibration prediction. It brings a step nearer the goal of an accurate ride vibration model of tractor behaviour which can be used as a design tool.