Abstract:

With excellent energy absorption properties of lightweight and high specific energy absorption， honeycomb material is widely used in various energy absorption protection structures. In this article， based on Voronoi diagrams and 3D printing technology， a novel gradient random honeycomb sandwich structure is designed and prepared. A finite element model of its three-point bending load is established and experimentally validated. Subsequently， based on the numerical model， crashworthiness research and multi-objective optimization design are conducted. The results show that for uniform random honeycomb sandwich structures， those with a lower degree of randomness have better energy absorption characteristics. Increasing the wall thickness increases the specific energy absorption but also leads to a larger load fluctuation coefficient due to the meso-structural deformation mode dominated by plastic hinges. When the relative density is consistent， the specific energy absorption of the random honeycomb sandwich structure with different cell size is not much different， and the decrease of cell size makes the deformation process more stable and reduces the bearing fluctuation coefficient. For cell size and cell wall thickness gradient random honeycomb sandwich structures， the introduction of a positive gradient of leads to a deformation mode dominated by both the support end and the loading end， which improves the energy absorption indicators. Based on the Non-dominated Sorting Genetic Algorthm-II （NSGA-II）， a multi-objective optimization of the positive gradient random honeycomb sandwich structures is performed. The obtained meso-structural parameters with optimal energy absorption characteristics show a 33.9% increase in specific energy absorption compared to the uniformly random honeycomb sandwich structure without optimization design.

Key words: random honeycomb, sandwich structure, 3D printing, energy absorption characteristics, multi-objective optimization