Packing behavior of cohesive deformable grains

Soft highly deformable particles are commonly found in biomass and industrial bio-products. Unlike most mineral grains, these particles exhibit significant deformation and shape changes even under moderate stress levels. In this study, we employ a continuum-discrete numerical approach to investigate the mechanical behavior of packings composed of cohesive soft disks. Our analysis includes the coordination number and particle shape evolution, the latter being quantified by a parameter that measures deviation from a circular shape. We find that during uniaxial compression of a packing initially composed of circular particles, the packing fraction at the jamming point, the coordination number and the shape parameter all increase with surface energy. During decompression, the combined effects of particle deformability and adhesion result in residual stresses and non-circular particle geometries. Both in loading and unloading, we observe a transition between a regime dominated by external stress and one dominated by internal cohesive stress.