Microstructural controls of anticrack nucleation in highly porous brittle solids

Abstract

porous brittle solids have the ability to collapse and fail even under compressive stresses. in fracture mechanics, this singular behavior, often referred to as anticrack, demands for appropriate continuum models to predict the catastrophic failure. to identify universal controls of anticracks, we link the microstructure of a porous solid with its yield surface at the onset of plastic flow. We utilize an assembly method for porous structures, which allows to independently vary microstructural properties (density and coordination number) and perform discrete element simulations under mixed-mode (shear-compression) loading. In rescaled stress coordinates, the concurrent influence of the microstructural properties can be cast into a universal, ellipsoidal form of the yield surface that reveals an associative plastic flow rule, as a common feature of these materials. Our results constitute a constructive approach for continuum modeling of anticrack nucleation and propagation in highly porous brittle, engineering and geo-materials.

Different erosion and entrainment mechanisms in snow avalanches

“…The adopted flow rule follows the principle of maximum plastic dissipation and gives a plastic flow that maximizes the plastic dissipation rate. The cohesive Cam-clay yield surface and the associative flow rule in this study have been recently proven to be satisfactory for simulation of porous brittle solids such as snow [24]. More details of the MPM and the constitutive model can be found in [15,25,26].…”

Three-dimensional and real-scale modeling of flow regimes in dense snow avalanches

“…Combined with the adopted flow rule, our plastic model fully satisfies the second law of thermodynamics. The elliptic shape of our yield surface and the associative flow rule have been recently shown to be appropriate for the simulation of porous brittle solids like snow (Ritter et al 2020 ). More details of the flow rule can be found in (Gaume et al 2018 ).…”

Towards a predictive multi-phase model for alpine mass movements and process cascades

“…The dynamics of snow avalanches were simulated using SPH (1) and with MPM (42,43,72). Furthermore, the MPM has been used to simulate both the release mechanisms and flow of unsaturated and saturated (5,71,86) slopes as well as slab avalanche processes which involve mixed-mode brittle fracture propagation (27), anticrack nucleation (7,63) and dynamics (28). Fluid simulations with MPM benefit from recent advances related to improved grid-to-particle transfer schemes such as the Affine Particle in Cell (APIC) method which preserves both linear and angular momentum (36) In contrast to most depth-averaged approaches, these particlebased methods rely on well established theories and constitutive frameworks such as elastoplasticity and critical state soil mechanics.…”