A flexible tire model for accurate prediction of off-road vehicle dynamics on soft soils

For several years now, co-simulation between Multibody Dynamics (MBD) codes like MotionSolve and Discrete Element Method (DEM) software like EDEM has been used for many applications such as vehicles and material transportation. One missing link has been a realistic tire model that not only could interact with the soil material in a realistic way but also show the influence of varying tire pressure, change in contact area and pressure distribution over said contact area.

For very soft material such as deep mud with a high-pressure tire, using a rigid wheel is a decent approximation. But for tires on harder surface, this method has several short comings. For example, a rigid representation of the tire will have neglectable rolling resistance while the pressure distribution on a real tire has its peak well ahead of the centerline of the tire producing a resisting moment to the motion. The contact patch area will in reality not depend on sinkage, but the sinkage is dependent on the contact area that is dependent on load and internal pressure.

This presentation introduces the new PM-FlexTire model that is integrated in EDEM and will work with MotionSolve. Requirements for creating and correlating the tire model is presented together with several application examples on mud, clay and gravel beds.

Presented at the ATCx Heavy Equipment in May 2021.

Speaker: Jesper Slattengren, Technical Fellow, Pratt Miller

Duration: 20 minutes