Agricultural Tractor Tyre Contact Area 3D Simulation Model Development using Altair EDEM

Lemuel Srinivasan P, Sr. Lead Engineer and Sanju Biradar of Mahindra present at the 2024 ATCx DEM.

Tractors are the most widely used agricultural machines, and their performance depends largely on the traction they can generate on the soil. Traction is the force that propels the tractor forward and enables it to pull the implement. Traction is influenced by many factors, such as tyre characteristics, soil properties, implement type, dynamic weight transfer and operating conditions. One of the key factors that affects traction is the tyre contact area (TCA), which is the area of the tyre that is in contact with the soil surface.

TCA is a parameter used to predict the tyre behaviour on soil. TCA determines the distribution of the vertical load and the horizontal shear stress between the tyre and the soil, and thus affects the slip ratio, the drawbar pull, and the power efficiency of the tractor. TCA also influences the soil compaction and the soil deformation caused by the tyre. Increasing the TCA would lead to increased traction and decreased ground pressure, reducing tyre sinkage and soil compaction. Measuring TCA experimentally is challenging, costly, and time consuming. One of the potential methods to overcome these limitations is the use of virtual simulation models. Among the various simulation methods, the engineering discrete element method (EDEM) is a promising technique to model the tyre-soil interaction, as it can capture the discrete nature and the dynamic behaviour of the soil particles, and account for the contact forces and the friction between the tyre and the soil.

The objective of this study is to develop a 3D simulation model of the agricultural tractor tyre contact area (TCA) using Altair EDEM, and to validate and apply the model to measure, evaluate, and optimize the traction performance of the tractor with different tyre sizes and tyre makes. To create a 3D soil model in Altair EDEM, and to calibrate the soil parameters, such as density, cohesion, friction angle, and restitution, based on the soil physical properties. To simulate the tyre-soil interaction in Altair EDEM, and to calculate the TCA and the traction performance indicators, such as slip ratio, drawbar pull (DBP). To validate the simulation results with the experimental data, and tyre selection for the new product development (NPD).