Experimental characterizations of fabric correlation in 2D rod assemblies subjected to biaxial shearing

Abstract

This study provides experimental evidence of the correlation between different fabric tensors in 2D granular assemblies subjected to shearing. Two testing assemblies with different elliptical rods were used and the shearing tests were conducted in a tailor-made biaxial cell. Both the rods and cell were produced using the 3D printing technique. Throughout the shearing, three fabric tensors, i.e., the particle orientation-based, the contact normal-based and the void-based fabric tensors, were studied. In particular, to obtain the void-based fabric tensor, the best-fit ellipse method was used, which can better describe the irregular void geometric information compared with the conventional methods described in the literature. In both samples, a strong linear relationship between the anisotropy intensity factors of the three fabric tensors was found. However, such a correlation was not identified when the void-based fabric tensor was quantified using the conventional methods. The discrepancy demonstrates the importance of properly quantifying the fabric tensor, and by using the best-fit ellipse method, the correlation between the fabric tensors can be better observed, which is crucial to understand the constitutive relationship in granules.