Modulation of elastic instabilities via particle interaction-induced stiffening in soft particulate composites

Soft materials can undergo large deformations while exhibiting highly nonlinear behavior. In soft particulate composites, this nonlinearity arises predominantly from geometry-mediated particle interactions and the intrinsic stiffening of the soft phases, which together govern the elastic instabilities and subsequent buckling patterns. In this study, we investigate how particle interaction–induced stiffening modulates elastic instabilities in soft particulate composites subjected to finite strains. We use the Gent material model, a non-Gaussian framework that captures the stiffening behavior through a single parameter associated with the limiting extensibility of polymer chains. Our results reveal that material stiffening modulates both the onset of instability and the transition between buckling modes, with outcomes strongly dependent on the initial geometry of the unit composite. These effects arise from variations in particle interactions along the loading and transverse directions. Thus, by strategically designing soft particulate composites via particle interaction-induced stiffening with tailored material properties and geometrical parameters, elastic instabilities can be effectively controlled and manipulated.