Universal features of anticrack nucleation in porous solids

Characterizing the nucleation of anticracks in porous materials under compression is a great challenge and has been the subject of several investigationsin different fields, from earthquake science, rock mechanics to avalanche research[1]. Yet, the conditions for the nucleation of anticracks still remain poorly known, especially under mixed-mode loading.In this study, we have conducted DEMsimulations of very loose, cohesive, granular assemblies with initial configurations which are drawn from Baxter’s sticky hard sphere (SHS) ensemble. The SHS model isemployed as a promising auxiliary means to independently control the average coordination number zcof cohesivecontacts and particle volume fraction φof the initial states. We focus on discerning the effectof zcand φon the elastic modulus, yield surface and plastic flow of the samples.Uniaxial compression simulations revealeda universal scaling behavior ofthe elastic modulus and the strength, which both scale with the cohesive contact densityνc= zcφof the initial state according to a power law.In contrast, the behavior of the plastic consolidation curveis shown to be independent of the initial conditions[2]. Furthermore, mixed-mode loading allowed us to evaluate the yield surface of the sampleswhichcan be approximated by an ellipsoid. The results suggest a universal form of the yield surface after a suitable rescaling of stress coordinates by the contact density. Evidence is providedthat such porous solids follow an associative plastic flow rule. Our model contributes to improve the parametrization of continuum anticrack models for porous cohesive materials such as snow for avalanche simulations.