Metal-coated hybrid meso-lattice composites and their mechanical characterizations

Developing cellular materials, especially ordered lattice structures, would allow the exploitation of structural advantages and enhance the mechanical performances. However, most lattice structures only consist of a single component material, while less investigations are focus on composite lattices and associated failure mechanisms. Here we fabricated nickel-coated polymer meso-lattice composites (Ni@PMLs) by 3D printing and electroless plating. A quantitative and in situ multi-scale experimental analysis assisted with a high-resolution imaging system was employed. Importantly, a simulation model for the composite was proposed and the damage process was elaborated based on the progressive damage theory and fracture mechanics. These results show that the average modulus and strength of Ni@PMLs can be enhanced by 68.3% and 34.9% respectively, compared to the polymer only lattices (PMLs). Furthermore, the average specific strength of the lattices almost reaches the upper bounds of conventional metal/polymer foams and natural cellular materials, despite that the cascade-shaped beams originating from our 3D printing process may have negative influence on mechanical performance, due to stress concentration and shear-induced failure. The simulated mechanical properties and damage propagation modes agree well with the experimental observations. These findings could be useful for the design/manufacturing optimization and future practical applications of meso-lattice composites.