DESIGN OF AUXETIC AND HYBRID HONEYCOMB STRUCTURES FOR ENERGY ABSORPTION APPLICATIONS: INVESTIGATION OF OUT-OF-PLANE UNIAXIAL COMPRESSION BEHAVIOR

摘要

Lightweight cellular structures are extensively used in various impact energy absorption applications, with traditional hexagonal honeycomb as the most popular structure for sandwich composite structures. Auxetic honeycombs are one of the emerging structures because of their unique mechanical properties and energy absorption capabilities. In our previous study we introduced a new auxetic-strut design along with two hybrid structures. The structures showed excellent in-plane compressive properties when compared with traditional honeycomb and reentrant auxetic structures. In this study the same structures are tested for their out-of-plane compressive properties. A comparative experimental study of five different structures is conducted on 3D printed samples. The deformation and failure modes of the different cells were studied and their performance was also discussed. Finite element modelling was carried out to validate the results. The out-of-plane properties of auxetic-strut design showed an increase of ~68% in the compressive strength, ~63% in Young’s modulus and ~32% in the total energy absorbed of auxetic-strut design when compared with traditional honeycomb structures. The hybrid structures also showed excellent out-of-plane properties. With better in-plane and out-of-plane properties, auxetic-strut design can be used in various energy absorption applications. Hybrid designs allow us to tailor properties of the structures with their specific in-plane and out-of-plane deformation modes.