Sand Behavior upon Alternating Triaxial Compression and Extension: A Multiscale Analysis Using LS-DEM

This study investigates the underlying mechanisms causing necking instability in granular materials. Using a digital twin created with the level-set discrete element method (LS-DEM), we simulate triaxial compression and extension cycles on a Hostun sand specimen within an x-ray tomograph. The simulation accurately replicates experimental observations, including stress-strain behavior, deviatoric strain field evolution, and necking initiation and progression during triaxial extension.