抄録
The objective of this study is to clarify the vibration generation mechanism of agricultural machinery caused by the interaction between the tire lugs and the road surface. It is important to investigate the lug excitation force occurring on a rolling agricultural tire in order to clarify the vibration generation mechanism. In our previous study, it is confirmed that the dynamic behavior of rolling tire is influenced by the vibration characteristics of the tire and only the rigid modes can affect the rolling tire behavior. Therefore, we modeled the tire as in-plane rigid ring model and the lug excitation force in longitudinal and vertical direction are identified. However, as for an agricultural tire, lateral direction lug excitation force also generates due to cross-stich lugs. In order to estimate lateral force, the rigid ring model to describe the out-of-plane tire dynamics is required. The three-dimensional rigid ring model (SWIFT model) is able to describe not only the in-plane tire dynamic but also the out-of-plane tire dynamics. So, the frequency equations of SWIFT model are derived and the model parameters are identified by minimizing the difference between measured and calculated natural frequencies. In this study, the shaft displacement and the shaft force during rolling motion are measured three-dimensionally by rolling test. From the measured data, the lug excitation force in longitudinal, vertical and lateral direction are identified by using SWIFT model.
