An enhanced square-grid structure for additive manufacturing and improved auxetic responses

Auxetic structures exhibit negative Poisson's ratios based on the deflection characteristics of the macrostructural forms generated by integrating specific base units. Considering the advantages of the abnormal metamaterial behavior, auxetic structures attained considerable research attention. While theoretical predictions indicate the possibilities to achieve very high auxetic responses, practical implementation and experimental validation were limited due to the difficulties in manufacturing the complex structural forms. Practical realization of true auxetic structural solutions attained a great impetus with the advent of the additive manufacturing solutions, opening up wider opportunities and renewed interests. The current research is an attempt towards enhancing the auxetic nature of a square grid structure by numerical and experimental methods. Finite element simulations allowed to identify structural changes for improved auxeticity and experimental validation based on selective laser melted structures proved the trends to be true. Experimental results based on the fabricated structure indicate the Poisson's ratio to be -7.