Heterogeneous geometric designs in auxetic composites toward enhanced mechanical properties under various loading scenarios

Abstract

Cellular architected materials have demonstrated exceptional energy absorbing and dissipating capability mostly under compression, but integrating such geometric design strategy into a practical scenario requires consideration of a more complex loading state. In this study, we evaluate geometric patterns for 3D-printed core lattices embedded in silicone rubber composite units that are subjected to uniaxial compression, a combined compression-shear load, and loading-unloading cycles. Mechanical properties of composite units with regular cellular patterns were characterized under different loading scenarios through experiments and simulations. Our results show that various geometric patterns exhibit different advantages under certain loading conditions. Then, we further develop heterogeneous geometric patterns to achieve tailorable and enhanced stiffness under compression and shear load. Finally, the developed composite units demonstrate excellent energy absorption under compressive loading-unloading cycles although slow stiffness degradations were observed. Our findings pave a way for integrating 3D printing into advanced composite designs for various energy-absorbing applications.