Advantages of Auxetic Circular Plates for Indentation and Impact Resistance: A Hypothetical Numerical Study

Compared with those made by traditional materials, the structures consisting of auxetic materials may have excellent impact resistance both experimentally and theoretically due to out-of-plane negative Poisson’s ratio (NPR). For the insight of auxetic effect in the process of indentation and impact, the influence of indenter shape and the discussion about the phenomenon of wrinkling are often ignored. To show the advantage of auxeticity without any other interference, the indentation and impact behaviors of conventional and auxetic circular plates were both simulated by means of finite element analysis (FEA) and compared based on a hypothesis that all the material parameters for those two plates are the same but only their Poisson's ratios are opposite. The various geometries of indenter, including round platform, prismatic, spherical and conical shapes, are considered. The advantage of auxeticity on indentation and impact was evaluated by comparing the change of in-plane displacement, the number of wrinkles and the stress distribution on the plates. The numerical results showed that the shape of the indenter had a critical influence on the number and area of wrinkles produced, which reveals part of the mechanism of auxeticity against indenter and impactor. As expected, irrespective of the impact conditions, the circular plate made of auxetic material exhibited better indentation and impact resistance than that made of conventional material.