| Popis: |
In a global context of energy saving, the ratio stiffness – mass is a key parameter for design of mechanical structures. To deal with this major concern, sandwich materials are finding an increasing use: the skins are designed to resist tensile and compressive stresses while the core needs to gather lightweight, shear stresses resistance and high mechanical energy absorption capacities. Firstly made of balsa wood, the core is nowadays classically realized using architectured materials (cellular materials, honeycombs, entangled materials, etc.). Entangled materials are architectured materials with tuneable properties, depending of the dedicated application. Several entangled materials already exist such as mineral or metallic wool; some of them are made of a single ductile metallic wire, entangled in all directions so that the final material becomes a porous continuous media. Such materials, which combine lightness and ductile behaviour, seem to be perfect candidates to dissipate energy during an impact. Compared to conventional materials such as balsa wood or honeycomb, a large amount of energy is indeed dissipated by friction coming from the numerous contacts due to the entanglement. The global aim of this work is focused on the study of energy dissipation mechanisms involved during impact as well as the correlation between architectural parameters of the material (wire diameter and material, volume fraction, etc.) and macroscopic behaviour. The first step that is presented here consists of an experimental investigation using dynamic compression tests to study macroscopic parameters (wire diameter, volume fraction, etc.) on absorbed energy. |
