Experimental Analysis of the Crushing of Auxetic Structure Under Compression

Abstract

Auxetic structures are increasingly used in all industrial fields due to their high mechanical properties. They possess a negative Poisson’s ratio. They contract laterally when they are subjected to compressive loads and extend when they are subjected to tensile loads. In this research contribution, an experimental study of the compression behavior of a re-entrant honeycomb structure is developed. The material used for the construction of the specimens is a poly-lactic acid reinforced with flax fibers. It is a biodegradable material and made from renewable resources. The specimens were manufactured using 3D printing technique. The influence of the number of cells and specimen’s height were measured and discussed. The results present their effect on the compression behavior and the energy absorption capacity. During compression tests, the cells deform elastically and collapse under high stress. Then, the cells crush gradually, forming folds on the cell walls. The densification phase begins when the folds consume the full height of the structure. The results showed that the number of the cells as well as specimen’s height play a major role on the mechanical behavior. The compression modulus and the energy absorption are found to be higher for auxetic structure with the high number of cells and height.