Biomimetic 4D printing of binary laminated composite bumper with integrated electro-induced shape recovery and chromic response

Automotive bumpers are essential for vehicle safety, which are evolving toward greater intelligence and multifunctionality. Inspired by the biomimetic prototypes, such as hollow structure of bamboo stems, shape recovery of corn leaves, and color-changing of octopuses, a coupled biomimetic automotive bumper is designed. Based on the mechanism of shape memory polymers (SMPs) that deform at ambient temperature and recover original shape through heating. A programmable multi-material 4D printing strategy is proposed by embedding conductive materials into shape memory polymers, which endows automotive bumpers with bending resistance, electrochromism and electro-induced shape recovery properties. The effects of structural design, printing parameters, voltage values and electrification time on the comprehensive performance of automotive bumpers are investigated. The printing strategy provides new ideas for the visual damage recovery and dynamic appearance adjustment.