An improved 3D multi-sphere DE-FE contact algorithm for interactions between an off-road pneumatic tire and irregular gravel terrain

摘要

The traveling analysis of an off-road tire on granular terrain is a typical application of contact interaction problems between structures and granular particles. In previous studies, extensive efforts normally idealized irregular gravel materials using spherical discrete elements (DEs), and the influence of irregular shapes was ignored. In our recent works, a coupling algorithm that used a multi-sphere model to accurately represent irregular gravel particles in the context of tire-terrain interactions was proposed. However, this algorithm suffers from low computational efficiency for contact interactions. To address this issue, this work develops a robust and efficient contact algorithm to handle the complex interactions between multi-sphere DEs and finite element segments for tire traveling analysis. The advantages of the presented algorithm are three-folded. Firstly, a rectangular dynamic contact domain is reconstructed to reduce the computational cost in the global searching phase with the use of an efficient multi-grid algorithm. Secondly, we use virtual bounding spheres instead of virtual bounding boxes for hexahedral FE segments to reduce memory storage. Thirdly, a numerical treatment is developed to deal with multi-point contact problems between multi-sphere DEs and FE segments using an inside-outside algorithm in the local searching phase. Finally, the traveling behavior of two off-road tires on multi-sphere gravel terrain using our proposed algorithm is simulated, and the robustness, accuracy and efficiency of the presented algorithm is demonstrated via an indoor soil-bin data.