Development of nacre-patterned multi-layer composites via 3D printing technology

Abstract

Patterned by the unique hierarchical architecture, nacre has exceptional impact resistance compared with the constituent materials. Hence, significant efforts have been devoted to developing new material systems with enhanced mechanical characteristics by duplicating such biological creatures. Although the key failure mechanisms inherent in nacre have been elucidated by numerous studies, guidelines for constituting optimized nacreous composites to yield the maximized mechanical performance have not been explored fully thus far. In this study, the key failure mechanisms of the nacre-like composites including nonlinear large deformation are in-depth studied under bending and impact loadings. Moreover, an optimal design of the nacre-like geometry is suggested through an integrated usage of dimensional analysis, 3D printing, mechanical testing, and numerical analysis. Three-dimensional nacre-mimetic composites with various configurations are designed and fabricated through a Voronoi diagram and FDM dual-extruder 3D printing technology. Then, each prototype is tested by bending and drop-weight impact tests and the failure behaviors governed by gradual debonding between platelets and matrices are elucidated. Additionally, both the bending and drop-weight impact tests are numerically simulated by the finite element method, and the modeling techniques for the nacre-like composites are validated. Subsequently, the main dimensionless parameters of the nacre-like structure are derived by dimensional analysis, and designed specimens are fabricated through 3D printing. Thereafter, the influence of the dimensionless parameters on the impact resistance is analyzed thoroughly with the drop-weight impact test of three different impact conditions. To reduce the design period while satisfying the target performance of the structures, the experiments are simulated by the developed numerical method. Lastly, a guideline for the optimal design of the nacre-like composites producing maximized impact resistance is established. This study can foster a feasible application of biomimetic composites in various industrial fields.