Breakthrough Virtual Development Capability for Soft-Soil Mobility Platforms and Vehicles

An Introductory webinar to PM-FlexTire™ by Pratt Miller, available through the Altair Partner Alliance. PM-FlexTire™ is an FE-based tire model that is integrated with the Altair EDEM™ soft-soil simulation platform and significantly expands what is possible in virtual development of soft-soil mobility. The model provides realistic deformation and high-fidelity forces and moments through co-simulation between EDEM and MBD code. Included time-varying air pressure model and detailed tread pattern interaction with particles are features not available in competitor solutions. Users can create models from tire CAD using various meshing solutions including Altair HyperMesh™ and Gmsh integrations, or can use meshes generated from other 3rd party meshing tools. Comprehensive integration with DEM simulation provides a high level of utility relative to alternatives to support increased scope of virtual development. Simulation complexity and licensing cost of PM-FlexTire™ and the corresponding integrations are "best fit" for virtual mobility development in soft-soil DEM simulation environments.


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


Top Use Cases for PM-FlexTire™ by Pratt Miller

Top use cases for PM-FlexTire™, a finite element-based tire model that is integrated with the Altair EDEM™ soft-soil simulation platform and significantly expands what is possible in virtual development of soft-soil mobility.

Use Cases

ATCx DEM 2020 - The need of proper modeling of traction control system in mobility simulations on soft soil

When building simulation models of military vehicles for mobility analysis over deformable terrain, the powertrain details are often ignored. This is of particular interest for electric and hybrid-electric vehicles where the maximum torque is produced at low speeds. It is easy to end up with the drive wheels spinning and reducing traction and eventually the vehicle digging itself down in the soil.

The presentation discusses the reason why simplified terramechanics models (ST) such as the Bekker-Wong models are not suitable for dynamic traction control studies and shows how Altair EDEM's complex terramechanics models (CT) can be co-simulated with multi-body dynamics software Adams using the ASCI interface.

The presentation focuses around an 8x8 transport vehicle with and without TCS. To model the traction control system a PD controller is used to limit the slip velocity at low speed and wheel slip at higher velocity. A soil model has been correlated to the Pratt & Miller sandbox and a 35% hill climb was used to tune the TCS parameters in the co-simulation.

Presented as part of the virtual ATCx Discrete Element Method in November 2020.

Speaker: Jesper Slattengren, Technical Fellow, Pratt Miller Engineering
Duration: 20 minutes