Quasi-static compression response and structural parameter optimization of CFRP 3D hybrid auxetic lattice structure with enhanced stiffness

This study presents a novel 3D hybrid auxetic lattice structure that exhibits excellent load-bearing capability and an enhanced negative Poisson's ratio (NPR) effect based on the stretching-dominated deformation mechanism. The proposed hybrid structure combines a double arrowhead part and a re-entrant quadrilateral part. 2D auxetic sheets are fabricated with carbon fiber-reinforced polymer (CFRP) composites and are assembled to build 3D structures via the interlocking method. Four structures formed with different design parameters are subjected to quasi-static compression loads to study their elastic properties and deformation behaviors through experimental tests and FE analysis. A parametric analysis is performed to investigate the effect and interactions of the design parameters on the mechanical properties using the Box–Behnken response surface method (RSM). The multi-objective optimization method is used to optimize design parameters with the aim of achieving the desired stiffness and NPR value. Testing results indicate that the proposed novel 3D hybrid auxetic lattice structure exhibits a significant improvement in structural stiffness over previously reported works. It can be a great candidate in practical applications where load-bearing capacity and NPR effects are simultaneously desired.