Reusability and energy absorption behavior of 4D printed continuous fiber-reinforced auxetic composite structures

This work proposed a strategy for fabricating intelligent continuous fiber-reinforced lattice structures (CFRLSs) for reusable energy absorption applications based on the cold-programming-induced shape memory effect. By integrating the smart material with continuous fiber, the CFRLSs can not only dissipate a considerable amount of energy but also recover their original shape after stimulation. Herein, two auxetic CFRLSs were developed to demonstrate their reusable energy absorption capacity. Specifically, the shape memory mechanism of the fiber-reinforced composites was first revealed, and the mechanical performance, reusability, and energy absorption capacity of the intelligent CFRLSs were investigated comprehensively. The result shows that CFRLSs present a preferable reusability with a shape recovery ratio above 90% in all test cycles and still exhibit a considerable energy absorption capacity compared to the pure Polylactic acid specimen, even after performing six test cycles. This approach provides a feasible way to design reusable protection devices and implementation in multi-functional applications.