Mechanical behavior of 3D-printed honeycomb sandwich structures with a hybrid cellular core designs
To be published on April 2, 2019 by SAE International in United States
Sandwich structures with honeycomb core are widely used in the lightweight design and impact energy absorption applications in automotive, sporting and aerospace industries. Recently, the auxetic honeycomb structures with negative Poisson's ratio (NPR), attract a substantial attention for different engineering products. In this study, we implement Additive Manufacturing (AM) technology, experimental testing, and Finite Element Analysis (FEA) to design and investigate the mechanical behavior of a new class of sandwich structure with an innovative core design. The new core model contains the conventional and auxetic honeycomb cells alongside each other to create a Hybrid Cellular Core (HCC) for the sandwich structure. The different sandwich structures with the same volume fraction are 3D printed using Fused Deposition Modeling (FDM) technique, and the comparative study on the mechanical behavior of conventional honeycomb, auxetic honeycomb, and HCC sandwich structures is conducted. The quasi-static uniaxial compression tests are performed on the printed samples to investigate the mechanical behavior of the 3D-printed sandwich structures. The deformation and failure modes of the different sandwich structures are studied at their cell level utilizing FEA of the compression test and experimental results. The new HCC sandwich structure shows higher mechanical properties (such as elastic modulus and crush stress) than the auxetic structure. However, the mechanical properties of the HCC structure are slightly less than the conventional honeycomb sandwich. The Poisson's ratio of the HCC sandwich is measured to be between the conventional and auxetic honeycombs and close to zero. Modifying the design variables of the HCC structure allows us to tailor the mechanical properties and deformation paths in macro level to achieve the desired properties in sandwich structures.