Measurement of Poisson’s ratio of the auxetic structure

Increasing performance demands in new technology applications have brought with the search for new materials. When it was challenging to achieve high performance and desired properties using traditional materials, the search for new materials was started. Recently, auxetic materials with a negative Poisson’s ratio have become the focus of attention due to their extraordinary properties. However, there are uncertainties for determining the Poisson’s ratio because they are in a cellular structure and the measurement method is not standardized. In addition, the experimental Poisson’s ratio measurement for auxetic structures has not been widely studied in the literature. The aim of this study is to systematically examine the effect of different measurement regions and target points selected over these regions on Poisson’s ratios of auxetic structures. For this purpose, Poisson's ratio of an auxetic structure with peanut-shaped holes was experimentally investigated using an image analysis software package program, and experimental results were compared with the results of numerical simulations. The results showed that the negative Poisson's ratio expressing the auxetic effect varies considerably depending on the chosen measurement region on a specimen.