What Controls Fabric: A Correlation Analysis for Contact Fabric Evolution in Granular Media

Abstract

Contact fabric is commonly adopted as a micromechanical state variable in many recent constitutive models of granular materials. This is accompanied by an evolution law for the fabric usually in terms of stress, total strain, plastic strain, or combinations thereof. However, there has yet to be a consensus on what variables best describe the evolution of contact fabric. The current study provides a correlation analysis for the evolution of the second-order fabric tensor in terms of stress and strain increments. An extended stress probing technique in two-dimensional (2D) discrete-element method simulations was used in order to thoroughly traverse the space of possible loading increments at multiple states prior to the stress peak in constant mean stress and simple shear simulations. Among the 15 hypotheses considered for fabric evolution, the correlation between the contact fabric and total strain appears to be the strongest. The plastic strain, despite its adoption in previous studies, shows a weak correlation with fabric. The results also uncover anomalies that are thought to be associated with the artificial sample preparation procedure.