An analysis of tire relaxation in conditions of the wheel side cornering agle oscilations

Results of laboratory experimental research of a truck tire, in conditions of side cornering angle dynamic changes are presented in this work. As research objects, there were 2 truck tires. These tires had different construction and as an effect they had different properties, including cornering resistance and relaxation length. Tires tests have been performed using the dynamometric trailer, fixed on the drum facility. During testing, the wheel side cornering angle oscillatory changes have been forcing, with frequency of 2 and 4Hz, in wide scope of the wheel rolling velocity. Chosen measurement results of lateral reaction force have been presented in time domain. Values of the lateral force oscillations amplitude and lateral force time lag have been observed. Amplitude and phase dynamic characteristics of tires, using FFT transformation, have been determined. A decrease of the lateral force oscillations amplitude and an increase of the lateral force phase shift with increasing input signal frequency, as the wheel cornering angle oscillations, have been shown. Conclusions about influence of the wheel rolling speed on tire relaxation effects in dynamic conditions have been formulated. There have been revealed that different properties of different tires types, described in quasistatic conditions have an influence on their behaviour also in dynamic conditions. Lower tire cornering resistance can decrease an amplitude of lateral force oscillations whilst greater tire relaxation length can decrease an amplitude and also can increase phase shift of lateral force oscillations.