Dynamic behavior of graded honeycombs – A finite element study

This paper aims to investigate the in-plane dynamic mechanical behavior of the functionally graded honeycomb. Finite element simulations were carried out using ABAQUS/EXPLICIT. In each case, a constant velocity was applied to the impact plate which then crushed the honeycomb. The values of the velocity were from 5 to 100 m/s. From the observation of the deformation profiles, three deformation modes have been identified when the strongest layer was placed at the impact end while two deformation modes have been found when the weaker layer was placed at the impact end. The critical velocities, at which the deformation modes transits were determined with a classification map. Dynamic stress and quasi-static plateau stress were obtained from the loading and the supporting plate, respectively. The stress–displacement curves were compared with the analytical prediction based on the shock wave theory. Then, the absorbed energy under constant velocity loading was investigated. To further investigate the influence of the stress gradient on the behavior of the graded honeycomb, different initial velocities versus the impinging mass were imposed on the impact plate. By considering a critical case, in which the velocity reduces to zero when the honeycomb structure is just fully crushed, the densification velocity was obtained. The results confirm that the positive gradient will enhance the energy absorption capacity of honeycombs.