Auxetic aluminum sheets in lightweight structures

Abstract This paper deals with the auxetic deformation behavior of periodically perforated aluminum sheets and their application for lightweight design. If commercially available metal sheets are provided with perforations, this can significantly change the mechanical properties of the sheets. For example, with certain perforation patterns, it is possible to achieve a negative Poisson's ratio in the sheet plane. Such material behavior is called auxetic. Macroscopic auxetic behavior can be explained by mechanisms that are based on the geometry of the perforation. Sheets are made of an isotropic aluminum alloy, provided with periodic perforation patterns and are mechanically characterized in tensile tests. The investigations focus on an exemplarily pattern with rectangular perforations leading to the auxetic behavior of the sheet. By means of passive thermography, highly stressed areas of the samples can be identified in situ and nondestructively during tests. The experimental results are verified in numerical simulations. The insights gained will help to better understand the mechanisms underlying the mechanical behavior of auxetically perforated sheet metal. Based on this, concepts for possible applications of auxetically perforated sheets in lightweight design can be developed for the future.