Gradient design of bio-inspired nacre-like composites for improved impact resistance

A novel brick-mud structure was proposed by introducing cell size gradient design into the nacre-like brick-mud microstructure. The gradient brick-mud structure samples were successfully prepared with the 3D printing technology. It was found through a pendulum impact test that the energy absorption of the gradient structure was higher than that of the uniform structure. With the gradient increase in the cell size, the energy absorption increased and could reach up to 4 times that of the uniform structure. A finite element simulation method was used to explore the energy absorption improvement mechanism of the gradient structure. The results showed that compared with the uniform structure, the gradient structure can achieve a much better stress distribution, which leads to greater bending deformation before fracture, thus improving strain energy storage. Moreover, the strain energy stored in the stiff material was about 2 times that of the soft material, and the strain energy stored in the interlayer soft material was 10 times that of the intralayer soft material.