Calibration of Model Parameters in 2D DEM for Soil-Grouser System.

For interaction studies in terramechanics, it has become popular to apply the Discrete Element Method (DEM) because of its capability in modeling local shear lines or large displacement of soil under various running gears. Through the development of in-house 2D DEM program for performance prediction of soil-grouser system, we conducted a reference experiment where quasi-2D condition could be assumed. Since the contact of elements is modeled by a linear contact model where a spring and a damper are connected in parallel, the necessary DEM parameters that should be calibrated are, therefore, spring constant, coefficient of friction, and coefficient of rolling friction if the critical damping condition is assumed. The soil model in the experiment is made of aluminum cylinder. Elemental density of model soil and radius are common between DEM simulation and the experiment. As for calibration process, the image-based procedure was applied to determine the coefficient of friction based on the angle of slope formed after the movement of a grouser system. Moreover, the coefficient of rolling friction was adjusted using drawings of soil model after the decision of the coefficient of friction. The normal spring constant was decided from the trial-and-error approach, the order of which was learned from the previous reports on DEM application in terramechanics. From this approach, the necessary parameters in 2D DEM could be adjusted to simulate performance of model grouser.