The energy absorption capacity of a novel dual-sub-fold Miura foldcore subjected to axial crushing

A modified Miura foldcore geometry was developed by introducing sub-folds into the cell walls of a conventional Miura foldcore. Similar to other sub-fold Miura foldcores, stable plastic hinge lines were generated at sub-fold sites under the guidance of the sub-folds and transformed into traveling hinge lines or stationary hinge lines in the subsequent crushing process. Therefore, in comparison to the conventional foldcore, the dual-sub-fold Miura foldcore exhibited a higher average crushing force with an improvement of 60.8 % in the optimum case. The dual-sub-fold Miura foldcore exhibited relatively lower stiffness at the sub-fold sites, effectively reducing the initial peak crushing force. This reduction in peak crushing force reached a maximum decrease of 70 %. Moreover, this dual-sub-fold foldcore was glued to two parallel rigid plates (top and bottom), making it more suitable for engineering applications. The parametric study indicated that the dual-sub-fold Miura foldcore exhibited predictable and stable deformation modes. It was found that the average crushing force could be effectively enhanced by reducing the core folding angle, elevating the sub-fold position, decreasing the sub-fold size, and elongating the foldcore. The theoretical model for predicting the energy absorption performance of the foldcore was also established.