The Application of Pulse Input Techniques to the Study of Tire Lateral Force and Self-Aligning Moment Dynamics in the Frequency Domain

This paper presents the application of pulse input techniques to study tire dynamics in the frequency domain. Many tire researchers analyze tire dynamics by means of studying the frequency response of tire output responses to sinusoidal frequency inputs, for example, the frequency response of tire lateral force to sinusoidal slip angle input. To replace expensive and time-consuming sinusoidal frequency tests, pulse techniques are applied to obtain frequency responses. A series of slip angle pulse input tests in various conditions (several normal forces, speeds and magnitudes of slip angle inputs) are executed on a pneumatic tire. The tire output responses to the slip angle pulse inputs are transformed into the frequency domain using discrete Fourier transform. Several rules of Fourier transform related to the study of tire dynamics are detailed. The frequency responses obtained by pulse techniques are validated by comparison with the results from sinusoidal frequency tests.