A modified honeycomb for better energy absorption capacity

These research works were carried out in collaboration with the Saint Louis Institute which is a research and development laboratory specializing in the defense sector. They were presented on the occasion of the LWAG 2022 meeting (Light-Weight Armor For Defense & Security) in Germany. In this study we assess the absorption properties of a sandwich panel, including the aluminum bee nest that makes up the heart, is equipped with new cellular configuration. These works contribute to the development of sacrificial panels for shields.

Typically when the panel is subjected to an ultra fast shock (some MS) such as an explosion, we can distinguish three regimes from deformation of the panel. The first phase is a linear elastic deformation over a very short time, it is the compression phase.

Once the compression peak has reached we enter a constant stress deformation diet, it is the crushing tray. Once this last past, the thickness of the structure is sharply reduced and the constraint quickly believes until the complete compaction, it is the densification regime.

In this study we study the influence of several geometric parameters of the honeycomb:

• Height;
• Cell diameter;
• The wall thickness;
• The influence of skins collage;
• Cellular configuration: hexagonal (classic) and modified by EC3D.

The various samples were subjected to normalized mechanical tests under quasi-static conditions (ASTM C365M and ASTM D7336M). Finite element digital correlations were made to assess the relevance of experimental results. Finally trials in real explosion conditions (rapid dynamics) were conducted to assess the differences in behavior.

The results of this study highlight the benefits of the new modified cell configuration. With equivalent material, equivalent density (preponderant parameter) and similar manufacturing cost, the performance of our structure is higher. Consequently this means that for equivalent mechanical properties our structure will require less material (up to -30%), which is an advantageous gain for many sectors.