Numerical study of open-top truncated pyramid folded structures with interconnected side walls against flatwise crushing

In this study, new types of folded structures with different base shapes (i.e. triangle, square and pentagon) are proposed. Each structure is folded from a thin sheet of aluminium, with the geometry of open-top truncated pyramid and connected inclination sidewalls. The purpose of this unique geometry is to increase the crushing resistance of the folded structure while maintaining a uniform collapsing behaviour under different crushing rates as compared with other existing folded kirigami structures. Three base shapes, i.e. triangle, square and pentagon, are considered in this study. Geometric parameters are derived for these structures based on three governing parameters: top and bottom edge length and cell height. Numerical models of these structures are firstly calibrated with quasi-static crushing test data followed by dynamic crushing simulations. To evaluate the crushing performances, structural responses including peak and average crushing stress, uniformity ratio and densification strain are compared among these three structures and also with the widely studied Miura-origami structure of the same density. Superior performances of crushing are observed for the proposed open-top truncated pyramid structure with higher average stress and more uniform collapsing under various loading rates, indicating potential application as energy absorber.