Structural actuation of 4D printed hygromorph biocomposites
Topic(s) : Special Sessions
Co-authors :
Jean-Baptiste LEDRU (FRANCE), Mickael CASTRO (FRANCE), Sofiane GUESSASMA (FRANCE), Antoine LE DUIGOU (FRANCE)Abstract :
Natural fibers are sensitive to moisture and this is considered as a major drawback for biocomposite development. However, based on biomimicry paradigm, Hygromorph BioComposites (HBC) has been proposed by Le Duigou et al.1. They consist of a biologically inspired architectured biocomposites with programmable shape-changing function (Fig 1d). The architecture follows an asymmetric lay-up with a so-called active layer made with transversally oriented biocomposite to trigger hygroexpansion 2 and a passive layer made with material having almost no hygroexpansion.
The main objective of this work is to study the force generation of a unidirectional continuous flax fibers (cFF) biocomposite lay-up when they are immersed in water. An attention will be laid on their architecture given by inspiration from biological structure being able to evidence trade-off between large displacement and force generation like wood can do. The architecture will be transferred into a dedicated material syntax following the 4D printing process parameters (Layer Height LH, Interfilament Distance ID, orientation φ) (Fig 1c).
First of all, cubic samples (5x5x5mm3) of unidirectional CFF/PLA (Fig 1b) were produced by a modified a MK3s PRUSA 3D printer according to the setup by Le Duigou et al4. An experimental protocol inspired by Perkytny et al5 on swelling pressure of wood samples during water immersion has been achieved to quantify the blocking forces, the maximum expansion and various constrained expansion. This last consist to measure an expansion with an applied force during. Tests have been realized on a rheometer ANTON PAAR 301 to facilitate accommodation with humid environment and the presence of force cellular (±50N). Figure 2.a) representing “force-stroke” curve of spruce wood (Fig.1a).samples realized a validation step of our experimental protocol. Extremums (orange circle) of the curve present the blocking force or maximal forces generated without displacement (10.5 ± 0.8 N) and maximum expansion or stroke generated without restriction (0.15±0.02 mm). Area under the extrapolation present the energy density (3.5± 0.8 J) generated by the sample which confirmed results of Shin et al 6.
Experiments carried out on biocomposites evidence that energy density generated is conditioned as function of slicing parameters such as LH and ID (25.3 J.cm-3 and 3.64 J.cm-3 for LH0.25 and LH0.35 respectively) (Fig 2.b). Its parameters reduction generate higher filament compression during printing implies material with lower porosity level. It results on a larger swelling force (85% in OP orientation) and hygroexpansion (154% in OP orientation). Results explain that the higher the porosity, the less surface interaction there will be between filament at meso and macro scale during sorption that results in force and displacement reduction.
Further work is under progress to evidence the potential of the active layer architecture on structural actuation and then on HBC performance.
The main objective of this work is to study the force generation of a unidirectional continuous flax fibers (cFF) biocomposite lay-up when they are immersed in water. An attention will be laid on their architecture given by inspiration from biological structure being able to evidence trade-off between large displacement and force generation like wood can do. The architecture will be transferred into a dedicated material syntax following the 4D printing process parameters (Layer Height LH, Interfilament Distance ID, orientation φ) (Fig 1c).
First of all, cubic samples (5x5x5mm3) of unidirectional CFF/PLA (Fig 1b) were produced by a modified a MK3s PRUSA 3D printer according to the setup by Le Duigou et al4. An experimental protocol inspired by Perkytny et al5 on swelling pressure of wood samples during water immersion has been achieved to quantify the blocking forces, the maximum expansion and various constrained expansion. This last consist to measure an expansion with an applied force during. Tests have been realized on a rheometer ANTON PAAR 301 to facilitate accommodation with humid environment and the presence of force cellular (±50N). Figure 2.a) representing “force-stroke” curve of spruce wood (Fig.1a).samples realized a validation step of our experimental protocol. Extremums (orange circle) of the curve present the blocking force or maximal forces generated without displacement (10.5 ± 0.8 N) and maximum expansion or stroke generated without restriction (0.15±0.02 mm). Area under the extrapolation present the energy density (3.5± 0.8 J) generated by the sample which confirmed results of Shin et al 6.
Experiments carried out on biocomposites evidence that energy density generated is conditioned as function of slicing parameters such as LH and ID (25.3 J.cm-3 and 3.64 J.cm-3 for LH0.25 and LH0.35 respectively) (Fig 2.b). Its parameters reduction generate higher filament compression during printing implies material with lower porosity level. It results on a larger swelling force (85% in OP orientation) and hygroexpansion (154% in OP orientation). Results explain that the higher the porosity, the less surface interaction there will be between filament at meso and macro scale during sorption that results in force and displacement reduction.
Further work is under progress to evidence the potential of the active layer architecture on structural actuation and then on HBC performance.