Prediction of the off-road rigid-ring model parameters for truck tire and soft soil interactions
Lardner, Kristian Lee
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Significant time and cost savings can be realized through the use of virtual simulation of testing procedures across diverse areas of research and development. Fully detailed virtual truck models using the simplified off-road rigid-ring model parameters may further increase these economical savings within the automotive industry. The determination of the off-road rigid-ring parameters is meant to facilitate the simulation of full vehicle models developed by Volvo Group Trucks Technology. This works features new FEA (Finite Element Analysis) tire and SPH (Smoothed Particle Hydrodynamics) soil interaction modeling techniques. The in-plane and out-of-plane off-road rigid-ring parameters are predicted for an RHD (Regional Haul Drive) truck tire at varying operating conditions. The tire model is validated through static and dynamic virtual tests that are compared to previously published literature. Both the in-plane and out-of-plane off-road rigid-ring RHD parameters were successfully predicted. The majority of the in-plane parameters are strongly influenced by the inflation pressure of the tire because the in-plane parameters are derived with respect to the mode of vibration of the tire. The total equivalent vertical stiffness on a dry sand is not as heavily influenced by the inflation pressure compared to predictions on a hard surface. For perspective, at 110 psi, the dry sand total vertical stiffness is nearly nine times smaller than that determined on the hard surface, while the lateral stiffness on soft soil (Dry Sand) is at a minimal of three times higher than that of the corresponding values tested on a hard surface. The cornering stiffness is primarily load dependant because the inflation pressure is only noticeably influential at high vertical loads. More importantly, the soil builds in front of the tire, creating what is called a bulldozing effect, during high slip angles. The additional lateral force of the soil exerted onto the tire during cornering maneuvers may contribute to higher than expected results and may be confirmed through future investigation of the cohesion of the soil model.