Self-expanding/shrinking structures by 4D printing

摘要: The aim of this paper is to create adaptive structures capable self-expanding and self-shrinking by means four-dimensional printing technology. An actuator unit designed fabricated directly fibers shape memory polymers (SMPs) in flexible beams with different arrangements. Experiments are conducted determine thermo-mechanical material properties the part revealing that process introduced a strong anisotropy into printed parts. feasibility features demonstrated experimentally. A phenomenological constitutive model together analytical closed-form solutions developed replicate behaviors SMPs. Governing equations equilibrium for based on non-linear Green–Lagrange strain tensor solved implementing finite element method along an iterative incremental Newton–Raphson scheme. material-structural then applied digitally design print SMP lattices planar tubular shapes comprising periodic arrangement units expand recover their original automatically. Numerical experimental results reveal proposed lattice as meta-materials can be employed plane actuators self-expanding/shrinking or structural switches providing two dynamic characteristics. It also shown mechanism serve stents grippers bio-medical piping applications.