Off-Road Soft Soil Tire Model.

UNCLASSIFIED: Distribution Statement A. Approved for public release.

Off-Road Soft Soil Tire Model

by Taheri, Sh., Sandu, C., Taheri, S., Naranjo, S., Jayakumar, P., Ross, B., Christ, D.

 

The dynamics of tire-terrain interaction plays a significant role in studying vehicle performance. Tire dynamics is influenced by tire structure and tire-terrain interaction. The main motivation of this study is the development of a highly efficient tire-terrain simulator that can account for a detailed behavior of the tire, especially in conjunction with soft soil, and which can be linked with commercial multi-body dynamics software.

In order to realistically model different sections of the tire, the proposed model consists of three layers, representing two side walls and tread and belt layer; each layer contains multiple lumped masses connected to each other with springs and dampers, acting as Kelvin-Voigt elements, in various combinations. A hybrid formulation approach is chosen in constructing the stiffness matrix, which allows the pressure and volume changing effect throughout the simulation.

The tire interaction with the terrain is obtained using an innovative ground model, which adapts its boundary conditions based on the dynamics of the tire elements. The ground model defines different switching surfaces in global vertical, longitudinal, and lateral directions, and switches between different sets of state-space differential equations to keep the system stable. The overall behavior of the tire structure in conjunction with ground model represents the actual viscoelastic behavior of the tire.

To optimize the computational time of the code, different techniques were used in memory allocation, parameter initialization, code sequence, and multi processing. Additionally, different modules like pressure effect, ground effect, tread effect, and others can be chosen to reduce the simulation time. Moreover, this multi layer structure of the code makes it capable of adopting its working frequency range based on the application.