Symmetric and asymmetric deformation transition in the regularly cell-structured materials. Part I: Experimental study

Quasi-static compressive response of regularly cell-structured materials is experimentally studied for various relative density, cell contact length and intercell bonding state. Each cell in this specimen is aligned in a hexagonal closed-pack array. The contact length as well as cell wall thickness of regularly cell-structured materials, plays an important role on the deformation mode transition. The deformation changes itself from symmetric to asymmetric pattern when increasing the contact length to cell-wall thickness ratio. Higher level of collapsing stress is observed in symmetric deformation due to the nearly uniform stress transfer during compression. Work hardening behavior is promoted with increasing the relative density or decreasing the contact length. Asymmetric deformation is associated with a nearly constant collapsing stress. The plateau collapsing stress state is caused by the localized deformation of cell-row in a narrow band of specimen. Liquid epoxy resin between cell walls also on the deformation mode of cell-structured materials. In the present study, the experimental observation is presented first (Part 1), followed by the theoretical analysis and comparison between experimental and analytical results in (Part 2).