Electro-induced shape memory effect of 4D printed auxetic composite using PLA/TPU/CNT filament embedded synergistically with continuous carbon fiber: A theoretical & experimental analysis

A novel strategy is proposed to fabricate continuous fiber-reinforced electro-induced shape memory auxetic composites (CFRSMCs) by combining conductive filaments and continuous carbon fiber through 3D printing technology. In the first step, the conductive filaments were manufactured based on Poly-lactic-acid/ Thermoplastic-urethane/Carbon-nanotube (PLA/TPU/CNT) blend nanocomposite, and the CFRSMCs were then prepared, composing different carbonaceous fiber content with a variety of extrusion width. The main aim of the present work is to evaluate the mechanical, electrical, and thermal properties as well as the shape memory effect (SME). With regard to this, the negative Poisson's ratio effect of the printed CFRSMCs was precisely assessed through tensile measurement, and a well-adjusted theoretical model was employed for further predictions. Accordingly, as compared to free-fiber printed samples, the CFRSMCs exhibited superb mechanical properties and rapid electro-induced SME (a recovery ratio of 94% under 10 V within 25 s). Moreover, due to tailoring coconductive networks by the CNTs and carbon fibers in the printed composites, a great deal of activation capability in the auxetic CFRSMCs could be revealed by various stimuli and for smart applications. This advanced strategy indicates a great potential to fabricate various auxetic electro-induced CFRSMCs used in small scale of deployable trusses or other lightweight smart components like adaptive energy absorption devices and humanscale orthopedic materials.

Automated summary

A novel strategy utilizing 3D printing technology to fabricate continuous fiber-reinforced electro-induced shape memory auxetic composites was proposed and evaluated for its mechanical, electrical, thermal properties, and shape memory effect. The CFRSMCs exhibited excellent mechanical properties and rapid electro-induced shape memory effect, showcasing great potential for smart applications.