MECHCOMP7 - 7th International Conference on Mechanics of Composites, Porto, Portugal, 1 - 03 September 2021, vol.1, no.1, pp.18
Composite sandwich structures have become more attractive materials, thanks to their high strength, rigidity, and lightweight. In addition to being designable for the desired working conditions and many advantages (easy to install and assembly, being easily reparable etc.); due to the porous and hollow structure of the core geometries forming the structure, they are also ideal materials for sound and heat insulation, especially in structural applications. By the production technologies developed in recent years, it has become possible to produce structures with Negative Poisson's Ratio (NPR), known as "metamaterials." These structures, also known as auxetic metamaterials, can exhibit unique mechanical properties thanks to their NPR feature. Compared to conventional materials, auxetic structures exhibit superior strength, better energy absorption capability, higher impact resistance, and shear modulus. In this study, two different sandwich structures (traditional hexagonal honeycomb and re-entrant auxetic) were produced by 3D printers. One of the structures is configured with a traditional feature and the other with NPR feature core geometry. Acoustic performances were measured with Acoustic Impedance Tube.
Furthermore, the Shock Loading behavior of the sandwiches was carried out by using a shock tube test set up. Thus, both the acoustic performances and the mechanical behavior of the structures under shock load have been studied experimentally. For both loading cases, the effect of auxetic core was studied and compared. Moreover, the results were discussed according to the wave speed.