A new design of star auxetic metastructure with enhanced energy-absorption under various loading rates: Experimental and numerical study

Cellular structures are widely used in various industrial applications due to their lightweight and high-strength properties. However, conventional cellular structures have some limitations in terms of energy absorption and load-bearing capacity. Therefore, novel cellular structures with enhanced performance are needed. This study introduces and evaluates two novel auxetic metastructures: Star Triangular Auxetic (STA) and Star Triangular Auxetic - Double Arrow (STA-DA). The metastructures are fabricated by material extrusion additive manufacturing and subjected to quasi-static axial crushing test at three loading rates. The tests are analyzed and validated by using digital image correlation and finite element modeling. The results show that the energy absorption of the STA structure is 19% higher than the STA-DA structure due to progressive damage and negative Poisson's ratio. However, the STA-DA structure has higher load-bearing capacity than STA due to its stiffness which is 170% higher than the average stiffness of STA. The proposed auxetic metastructures show promising potential for industrial applications that require lightweight and high-strength structures with enhanced energy absorption.