IN-PLANE COMPRESSION BEHAVIOR OF SINUSOIDAL HONEYCOMB WITH CIRCULAR NODES

Curved wall honeycomb can effectively improve the problem of stress concentration in straight wall honeycomb under in-plane compression load. To further enhance the impact resistance of curved wall honeycomb, a novel sinusoidal honeycomb with circular nodes (CSH) was obtained by inserting thin-walled circular rings at the nodes of the orthogonal sinusoidal honeycomb (OSH) which has been reported. Two kinds of 3D printed polylactic acid (PLA) honeycomb specimens were prepared for quasi-static compression experiments, and these experiments were numerically simulated in LS-DYNA software. There is a good agreement between the experimental and numerical results. Compared to OSH, the second plateau stress of CSH is greatly increased due to the addition of the circular nodes. The effects of geometric parameters and impact velocity on the mechanical properties of CSH under in-plane compression were systematically studied by the validated numerical simulation methods. The results show the stress-strain curve of CSH at low velocity has two plateau stages. Based on the deformation mechanism of honeycomb cells at different stages, the theoretical solutions of the two plateau stress are derived, which are consistent with the numerical simulation results. The first plateau stress of CSH is hardly affected by the circular radius, but increases with the decrease of the amplitude and the increase of wall thickness. The second plateau stress increase with the decrease of the amplitude and the increase of circular radius and wall thickness. In addition, stress-strain curve of CSH has a stress enhancement stage caused by the flattening deformation of circular nodes between the second plateau stage and the densification stage, which is very beneficial to improve the energy absorption of CSH. The total specific energy absorption of CSH before the densification strain increases with the decrease of amplitude and the increase of circular radius and wall thickness. When the impact velocity increases from 2m/s to 100 m/s, the negative Poisson's ratio effect of CSH gradually weakens, but even when the velocity is as high as 100 m/s, CSH still has a slight negative Poisson's ratio effect. The energy absorption performance of CSH is better than that of OSH under the impact of various velocities, especially at low and medium velocities, and the specific energy absorption of CSH is increased by 1.84 times and 0.75 times, respectively.