SIGNIFICANCE OF ROLLING RESISTANCE: WHEN IS IT REQUIRED?

As a means to replicate the behavior of non-spherical realistic particles in the discrete element method (DEM), artificially limiting the rotations of commonly used spherical particles or circular discs by rolling resistance has gained popularity [1]. Rorato et al. [2] suggested that a rolling resistance of 0.1963 is required to replicate the triaxial response of sands composed of rounded grains representing a unit value of sphericity. This study aims to confirm whether the application of rolling resistance is essential for replicating the plane strain response of round granular media. To achieve this, the authors conducted biaxial shearing experiments on granular samples composed of dual sized aluminum Schneebeli rods with perfectly circular cross-sections. The rotational behavior of the rods was identified through image analysis. Subsequently, a DEM model of the biaxial experiment was developed to simulate the shearing response of the circular particles under the same particle size and shape distribution. The findings indicated that replicating stress-strain and particle rotational responses of perfectly circular discs does not necessitate rolling resistance. The requirement for rolling resistance arises primarily from discrepancies in shape, while the DEM reasonably predicts realistic granular responses without rolling resistance for twin-shaped samples.