Shock wave propagation of nest-like structures under axial impact

• We investigate the dynamic behavior of nest–like structures under uniaxial impact. • A confined deformation zone forms near the loading end during the impact. • We proposed a rigid–perfectly–plastic–locking (R–P–P–L) shock model, to quantitatively predict how the confined propagates. Inspired by natural bird nests, nest-like structures consist of randomly packed slender particles confined within a container. This study investigates the dynamic behavior of nest-like structures by finite element simulation and a shock model. Under dynamic impact conditions, the nest-like structures exhibit distinct mechanisms compared to quasistatic loading. A confined deformation zone with nearly uniform stress forms near the loading end. This zone propagates steadily into the undeformed region at a constant velocity. Notably, the expansion speed exceeds the loading rate but remains significantly slower than the stress wave speed in solid material. We proposed a rigid-perfectly plastic-locking (R-P-P-L) shock model to quantitatively establish how initial conditions govern two critical dynamic responses: the stress in the confined zone and the expansion velocity of the confined zone. These dynamic characteristics of nest-like structures demonstrate their potential for impact resistance.