An analysis of tire relaxation process during dynamic changes of cornering angle

The work presents results of laboratory experimental research of a truck tire in dynamic motion conditions. Researches were performed using dynamometric trailer and dual drum facility for tire dynamics testing. The research object was a new structure truck, tubeless tire (275/70R22.5) with steel cord included also in carcass and bell. Tested tired wheel was rolling over steel drum surface with different speed. A wheel cornering angle was forces with different increase and similar decrease rate. The control system of hydraulic wheel turning mechanism was controlled by the voltage signals generated by software, through the D/A converter card. Values of cornering angle and also lateral reaction force transmitted by tested wheel were measured during tests performing. Changes of lateral reaction force values, transmitted by a tired wheel depending on forced wheel cornering angle were observed. Tire behaviour in the conditions of wheel cornering angle variations at different wheel rolling speed is presented. An influence of tire relaxation on values of transmitted lateral reaction force, during forcing of wheel cornering angle, is presented. As a result, there are presented differences in transient tire behaviour during forcing of wheel cornering angle with different increase rate and at different wheel rolling speed. A scope of wheel motion conditions are indicated, where tire relaxation can be important in case of modelling its interaction with the ground in the aspect of vehicle driving safety and comfort. Lateral reaction force value, transmitted by a wheel, the tire relaxation phenomenon becomes less significant when the rolling speed increases, the cornering angle value increases and when the rate of the wheel cornering angle variation rate decreases. It has been also shown that the relaxation phenomenon occurs both when cornering angle increases or decreases.