Comprehensive Study on Shape Shifting Behaviors of Thermally Activated Hinges in FDM-based 4D Printing

Abstract

4D printing of shape shifting structures, aka “hinges”, has raised a new standard in many fields. By using these hinges in certain parts of a 3D printed structures, a pre designed complex 3D shape with potential multifunctional application can be achieved from flat structure. This paper proposes a comprehensive semi-empirical model to predict the final shape shifting behavior and magnitude of the hinges printed by FDM process. First, all FDM main parameters are selected and reduced by design of experiment to printing speed, lamina thickness, nozzle temperature as well as printing pattern. In order to develop the model, a time-dependent constitutive model with these four process parameters were extracted for strain of an SMP homogeneous single layer structure using a fractional Zener model accompanied with Multiple Linear Regression (MLR) technique. Thereafter, the mathematical relations for shape shifting behavior of bilayer 4D printed structures were developed for beam bending and twisting by modifying Timoshenko’s constitutive equations. A comprehensive shape-shifting model was established including 3D printing parameters, angles, thickness ratios, activation time and temperature which was compared to the experimental data and results predicted both shape shifting behavior and magnitude of the hinges with good agreement. In addition, a novel flowchart was suggested to design and achieve the desired shape shifting behaviors. The proposed model and flowchart are novel tools to design 4D structures through desired shape-shifting of the hinges.

Fused deposition modelling: Current status, methodology, applications and future prospects

“…Therefore, 4D printing using FDM is an emerging innovation in AM that encompasses active materials in the printing process to fabricate a 3D object that can perform an active function [70]. This FDM-based 4D printing technology has opened new application fields such as thermally activated hinges [71], 3D-printed orthoses [72], high-performance and shape memory thermosets [73] and biomedical and tissue engineering technologies [74].…”

4D-Printed Tool for Compressing a Shape Memory Polyurethane Foam during Programming

“…This could be achieved by a folding mechanism, in which a hydrophilic polymer as a water-responsive active component exerted pressure on a rigid counterpart during swelling and thus caused the deformation of the overall structure. The concept was later transferred to the AM technology fused filament fabrication (FFF) by printing thermoresponsive objects [32][33][34][35][36][37][38][39][40][41]. At the molecular level, parameters like nozzle temperature, printing pressure and printing speed influence the orientation of polymer chains.…”