Mechanical properties of 3D auxetic closed-cell cellular structures

A novel 3D closed-cell cellular structure with different negative Poisson's ratio under tension and compression was presented. The 3D closed-cell cellular structure was generated by assembling the plane repeat units and sinusoidal wavy sheets units into the frame seamlessly. Four kinds of cellular structures with different responses under tension and compression are introduced. The mechanical properties of the proposed models were investigated. By choosing different repeated units, either positive or negative Poisson's ratio in three orthogonal directions can be achieved. Experiments and numerical simulations results show that the 3D closed-cell cellular structures have different responses under tension and compression loads. Considering material nonlinearities, the numerical results are analyzed using the instantaneous Poisson's ratio. The instantaneous Poisson's ratio can transit from negative to positive as the loads increase in 4 models. The results show that we can predict the auxetic response in a specific direction based on the repeated units that assembled into the frame. This designed structure provides an effective way to achieve a combination of negative, positive or zero Poisson's ratio.