Increasing dimension of structures by 4D printing shape memory polymers via fused deposition modeling

Abstract

The main objective of this paper is to introduce a 4D printing method to program shape memory polymers (SMPs) during fabrication process. Fused deposition modeling (FDM) as a filament-based printing method is employed to program SMPs during depositing the material. This method is implemented to fabricate complicated polymeric structures by self-bending features without need of any post-programming. Experiments are conducted to demonstrate feasibility of one-dimensional (1D)-to 2D and 2D-to-3D self-bending. It is shown that 3D printed plate structures can transform into masonry-inspired 3D curved shell structures by simply heating. Good reliability of SMP programming during printing process is also demonstrated. A 3D macroscopic constitutive model is established to simulate thermo-mechanical features of the printed SMPs. Governing equations are also derived to simulate programming mechanism during printing process and shape change of self-bending structures. In this respect, a finite element formulation is developed considering von-Kármán geometric nonlinearity and solved by implementing iterative Newton–Raphson scheme. The accuracy of the computational approach is checked with experimental results. It is demonstrated that the theoretical model is able to replicate the main characteristics observed in the experiments. This research is likely to advance the state of the art FDM 4D printing, and provide pertinent results and computational tool that are instrumental in design of smart materials and structures with self-bending features.

Automatic Transformation of Membrane‐Type Electronic Devices into Complex 3D Structures via Extrusion Shear Printing and Thermal Relaxation of Acrylonitrile–Butadiene–Styrene Frameworks

“…After the device is gently removed from the handling wafer, a slight amount of residual water underneath the device layer enables easy, smooth transfer (Figure b). Separately, an ABS film is prepared via ESP of transparent ABS filament (PLASIL, source material: LG Chem, ABS HI121H) through a heated nozzle (diameter: 0.4 mm; 230 °C) onto a glass substrate (120 °C) with a 3D printer (Sprout, Former's Farm) by the fused deposition method (the distance of the nozzle from the glass substrate = 0.1 mm and the ESP speed (υ ESP ) = 30 mm s −1 ) (Figure c); the ABS film prepared via ESP has residual stress due to the alignment of polymer chains . We note that the nozzle temperature was set to be the highest temperature within the feasible range (200–230 °C according to the datasheet from LG Chem) to obtain a film surface that is as smooth as possible.…”

“…This is because patterning via ESP on a stress‐free film generally induces residual shear stress and because transformation of the film is possible through an annealing process above the glass transition temperature ( T g ). The shape can be controlled by adjusting various parameters, such as the nozzle temperature, printing speed, printing pattern, porosity, and geometric dimensions (e.g., length, width, and thickness) . To the best of our knowledge, transformation examples at the electronics level via the indirect method have not been studied.…”

Characterization of three‐dimensional printed thermal‐stimulus polylactic acid‐hydroxyapatite‐based shape memory scaffolds

“…Self-bending structures [45] Polyeurathane-0- 15 Self-bending structures [24] T A B L E 1 (Continued)…”

A taxonomy of shape-changing behavior for 4D printed parts using shape-memory polymers

“…Figure 8 illustrates the bending behaviorbehavior, and if an array of the segments are arranged by altering the materials and position of fibers, it would also be possible to achieve Tibbits [54] Ionov [20] Folding deformation is caused by a stress mismatch between rigid and active materials, which is possible with various swelling ratios [10] Bending Gladman et al [15] Wu et al [54]. Zhang et al [57] Bending deformation is the swelling/shrinkage mismatch between both layers in response to activation stimuli, while sustaining the same strain at the interface between both layers, could result in different types of deformation [6] Rolling Ge et al [13] Gladman et al [15] Rolling deformation is a normalized curvature that varies depending on both the expansion mismatch and the thickness, which is a nonlinear relationship between the rolling radius of one hand and the ratio of expansion and the sample thickness [4] Twisting Ge et al [13] Wang et al [53] Zhang et al [57] Twisting deformation printed the fibers with certain angles to induce twisting, and by adjusting the print angles of active fibers, the final twist angle would be changed [57] Helixing Zhang et al [57] Ionov [20] Helixing deformation is made by a uniaxial expanding/shrinking active layer for a nonzero angle between the main straining direction of the active layer and the main axis of the bilayer strip [21] Buckling Manen et al [31] Sharon and Efrati [46] Buckling deformation that compressive stresses above a certain critical value will induce out-of-plane buckling of the flat structure [31] Curving Tibbits [51] Based on the light intensity gradient along the thickness of material, a stress gradient could be created, which results in spontaneous curving of the structure after release from the substrate [58] Topographical change Hu et al [17] Tibbits et al [52] Mountain and valley features can be generated from concentric circles in the presence of an appropriate stimulus. Surface topography is the representation of local deviations of a surface from a flat plane.…”