On impact behaviors of 3D concave structures with negative Poisson's ratio

Lattice structures with high mechanical properties and lightweight performance attracted increasing attention to the application of automotive, railway vehicle, and aerospace industries. This work developed a novel three-dimensional concave lattice structure using a hyper-elastic soft photopolymer via the digital light processing technique. The axial low-velocity impact behaviors of the proposed structures were investigated by a drop hammer machine and numerical simulation. The results showed that the novel 3D concave structures could present continuous auxetic behaviors with large negative Poisson's ratios. The structural design parameters such as concave angle and thickness had significant effects on Poisson's ratio and energy absorption. Specifically, the structures with concave angles from 10 degrees to 20 degrees and with thicknesses from 0.5 mm to 1.0 mm presented the higher negative Poisson's ratio. The highest negative Poisson's ratio of-0.86 was obtained. This work offered a new insight into designing novel meta-lattice structures with improved impact resistance.