In the article, “ Bending behaviour of sandwich composite structures with tunable 3D-printed core materials,” Department of Mechanical Engineering, State University of New York (2017) has stated that they successfully manufactured a novel class of sandwich composites with 3D-printed core materials and Carbon Fiber Reinforced Polymer face sheets. They accomplished this through numerical analysis using Finite Element Analysis simulations and real-life experiments. This was done to bridge the two data types together, to prove its scalability and its feasibility. Three-point bending tests were done on three different types of sandwich cores, to investigate the bending behaviour on the cores.
They stated that the structures that the cores had were: Truss, Conventional Honeycomb, and Re-entrant Honeycomb. Through the study of the structure, they discovered that the latter structure, an auxetic structure, possesses a negative Poisson’s Ratio. They stated that this has many mechanical advantages such as “increased indentation resistance, shear resistance, plain strain fracture toughness, and energy absorption”.
Through experiments and computer simulations, they showed that the truss structure has the best overall stiffness, whereas the Re-entrant honeycomb proved to have the least amount of stiffness with peak forces of 600N, and 450N respectively. However, due to the high stiffness of the truss structure, it made the structure to have the least amount of flexibility. The re-entrant was opposite of the truss structure, with it being able to have a flexural displacement of 15mm before plastic failure, compared to the truss structure’s displacement of only 2.5mm.
The data gathered from this paper illustrates to us the potential of tunable cores. Cores that can be tuned to produce specific properties for its specific intended use. Components that need ultimate tensile strength can be obtained using cores with truss structures. Likewise, components that need flexural strength, can rely on re-entrant honeycomb cores.
References
Li, T., & Wang, L. (2017). Bending behavior of sandwich composite structures with tunable 3D-printed core materials. Composite Structures, 175, 46–57. doi: 10.1016/j.compstruct.2017.05.001
Zulhusni Jumat 