How to Setup Tire Motion in EDEM
There are two primary options for defining flexible tire motion in Altair EDEM using PM FlexTire™:
Using EDEM’s built-in kinematics, force, and torque controllers
- Simplest to implement and fastest to solve.
- Limited in functionality compared to coupled simulations.
Using an MBD solver (Altair MotionSolve) for coupled simulation
- Recommended for full vehicle simulations with independent suspension, undulating terrain, or variable travel direction.
When to Use EDEM to Define Motion
- Calibrating PM FlexTire™ input parameters based on:
- Tire radial deflection under load
- Rolling resistance
- Performing single-wheel or multi-tire tests to predict:
- Tractive effort
- Soil compaction
- Tractive power requirements
- Maximum tractive force
- Controlled forward velocity with free-spinning tire(s)
- Controlled or torque-limited rotational velocity
When to Use MotionSolve to Define Motion
Use MotionSolve for:
- Full vehicle simulations
- Independent suspension modeling
- Terrain following with slope changes
- Maneuvers requiring directional changes
Coordinate System Reference
The figure below shows the tractor tire in EDEM, defining the coordinate system used for all motion inputs and outputs.
Option 1: EDEM Controlled Forward Velocity
In this setup:
- Forward velocity is controlled and held constant.
- Tire rotational velocity responds naturally based on soil-tire interaction.
Required EDEM settings:
Linear Force Controller
- Apply constant vertical load (e.g., 40 kN).
- Optional: Damping coefficient, gravity, speed cap.
- Constrain motion in vertical direction.
Linear Translation Kinematic
- Apply constant forward speed (e.g., 2.78 m/s).
- Disable “Moves with Body.”
- Use Global reference space; direction: -X.
Torque Controller
- Allow tire to rotate freely.
- Set torque to zero on all axes.
- Optional: Damping coefficient, angular speed limit.
- Enable “Moves with Body.”
- Constrain rotation to tire’s axis (typically Y-axis).
Option 1 EDEM Controlled Forward Velocity - Responce
When using this approach to define tire motion, the forward velocity is controlled and held constant, while the tire's rotational velocity is calculated based on the interaction between the free-spinning tire and the soil bed, as governed by the torque controller. This setup allows the rotational speed to respond naturally to the soil-tire interaction, as illustrated in the figures below.
Option 2: EDEM Controlled Rotational Velocity
In this setup:
- Rotational velocity is controlled and held constant.
- Forward velocity responds naturally to the soil-tire interaction.
Required EDEM settings:
Linear Force Controller
Linear Rotational Kinematic
- Apply initial rotational speed (e.g., 180 deg/s).
- Use Global reference space.
- Enable “Moves with Body.”
- Constrain rotation to tire’s axis (typically Y-axis).
Linear Force Controller
- Apply zero force in Z, X, Y unless draft force is needed.
- If applying draft force, add force opposite to travel direction.
- Optional: Gravity, damping, speed cap.
- Constrain motion along the X direction.
Option 2 EDEM Controlled Rotational Velocity - Responce
When using this approach to define tire motion, the rotational velocity is controlled and held constant, while the tire's forward velocity is calculated based on the interaction between the spinning tire and the soil bed. This setup allows the forward speed to respond naturally to the soil-tire interaction, as illustrated in the figures below.
Option 3: EDEM Torque-Limited Rotational Velocity
Useful for examining single-tire drawbar pull tests.
In this setup:
- Rotational speed and applied torque are limited.
- Forward velocity responds naturally to draft load and soil-tire interaction.
Required EDEM settings:
Linear Force Controller
Torque Controller
- Apply non-zero torque (e.g., 1000 N·m about Y-axis).
- Set initial rotational speed (e.g., 180 deg/s).
- Optional: Damping, angular speed limit.
- Enable “Moves with Body.”
- Constrain to tire’s axis.
Linear Force Controller
- Apply zero or draft force opposite to travel direction.
- Optional: Gravity, damping, speed cap.
- Constrain along the X direction.
Option 3 EDEM Torque Limited Rotational Velocity - Responce
Using this approach to define tire motion, the applied torque and rotational speed are limited, while the tire’s forward velocity is calculated based on its interaction with the soil bed, as managed by the torque controller. In this example, a gradually increasing draft load is applied to the tire. This setup allows the forward speed to respond naturally to the combined effects of the draft load and the soil-tire interaction, as shown in the figures below.
How to Video
The Step-by-step video can be access here: Altair How-to-Video
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