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Sequential Self-Folding Structures by 3D Printed Digital Shape Memory Polymers.

Mao Y, Yu K, Isakov MS, Wu J, Dunn ML, Jerry Qi H - Sci Rep (2015)

Bottom Line: A simplified reduced-order model is also developed to rapidly and accurately describe the self-folding physics.An important aspect of self-folding is the management of self-collisions, where different portions of the folding structure contact and then block further folding.A metric is developed to predict collisions and is used together with the reduced-order model to design self-folding structures that lock themselves into stable desired configurations.

View Article: PubMed Central - PubMed

Affiliation: The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.

ABSTRACT
Folding is ubiquitous in nature with examples ranging from the formation of cellular components to winged insects. It finds technological applications including packaging of solar cells and space structures, deployable biomedical devices, and self-assembling robots and airbags. Here we demonstrate sequential self-folding structures realized by thermal activation of spatially-variable patterns that are 3D printed with digital shape memory polymers, which are digital materials with different shape memory behaviors. The time-dependent behavior of each polymer allows the temporal sequencing of activation when the structure is subjected to a uniform temperature. This is demonstrated via a series of 3D printed structures that respond rapidly to a thermal stimulus, and self-fold to specified shapes in controlled shape changing sequences. Measurements of the spatial and temporal nature of self-folding structures are in good agreement with the companion finite element simulations. A simplified reduced-order model is also developed to rapidly and accurately describe the self-folding physics. An important aspect of self-folding is the management of self-collisions, where different portions of the folding structure contact and then block further folding. A metric is developed to predict collisions and is used together with the reduced-order model to design self-folding structures that lock themselves into stable desired configurations.

No MeSH data available.


(a) The schematic graph of the helical SMP component. Series of photographs showing the shape recovery process of the helical SMP component (a) with uniform hinge sections, and (c) with graded hinge sections.
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f2: (a) The schematic graph of the helical SMP component. Series of photographs showing the shape recovery process of the helical SMP component (a) with uniform hinge sections, and (c) with graded hinge sections.

Mentions: We design, fabricate by digital SMP printing, and test a seemingly-simple helical structure where rigid (non-active) panels are connected by active hinges on each corner with a radius of 5 mm (Fig. 2a). The thickness of the panels and hinges is 0.8 mm, the depth is 6 mm and the clearance between neighboring panels is 5 mm. We program the self-folding structure by unfolding it into flat at an elevated programming temperature, which results in each of the hinges bending to the prescribed curvature. Here the prescribed curvature is achieved by a simple state of deformation (bending) and is amenable to analysis, but in general more complex deformations can be programmed. We then recover the desired final configuration by heating the structure uniformly to Tr. To demonstrate the importance of the folding dynamics and self-collisions in the process we design two structures that have identical geometry, but each has a different set of materials used for the hinges. In Sample 1 each of the 9 hinges uses the same SMP material (H-3), and in Sample 2 the hinges are made from seven different materials (H1-H7; Table 1). After printing the structure we deform it into a flat configuration in hot water at TH = 90 °C, which is above the Tg of all of the SMP sections. Then the sample is cooled to TL = 10 °C, at which all the SMP hinges are in their glassy states. After releasing the external load, the structure is fixed at the temporary straight shape. To activate the shape recovery of the structure, we immerse it in hot water with Tr = 90 °C so that all hinges experience the same thermal conditions. The shape recovery process is monitored by a video camera.


Sequential Self-Folding Structures by 3D Printed Digital Shape Memory Polymers.

Mao Y, Yu K, Isakov MS, Wu J, Dunn ML, Jerry Qi H - Sci Rep (2015)

(a) The schematic graph of the helical SMP component. Series of photographs showing the shape recovery process of the helical SMP component (a) with uniform hinge sections, and (c) with graded hinge sections.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562068&req=5

f2: (a) The schematic graph of the helical SMP component. Series of photographs showing the shape recovery process of the helical SMP component (a) with uniform hinge sections, and (c) with graded hinge sections.
Mentions: We design, fabricate by digital SMP printing, and test a seemingly-simple helical structure where rigid (non-active) panels are connected by active hinges on each corner with a radius of 5 mm (Fig. 2a). The thickness of the panels and hinges is 0.8 mm, the depth is 6 mm and the clearance between neighboring panels is 5 mm. We program the self-folding structure by unfolding it into flat at an elevated programming temperature, which results in each of the hinges bending to the prescribed curvature. Here the prescribed curvature is achieved by a simple state of deformation (bending) and is amenable to analysis, but in general more complex deformations can be programmed. We then recover the desired final configuration by heating the structure uniformly to Tr. To demonstrate the importance of the folding dynamics and self-collisions in the process we design two structures that have identical geometry, but each has a different set of materials used for the hinges. In Sample 1 each of the 9 hinges uses the same SMP material (H-3), and in Sample 2 the hinges are made from seven different materials (H1-H7; Table 1). After printing the structure we deform it into a flat configuration in hot water at TH = 90 °C, which is above the Tg of all of the SMP sections. Then the sample is cooled to TL = 10 °C, at which all the SMP hinges are in their glassy states. After releasing the external load, the structure is fixed at the temporary straight shape. To activate the shape recovery of the structure, we immerse it in hot water with Tr = 90 °C so that all hinges experience the same thermal conditions. The shape recovery process is monitored by a video camera.

Bottom Line: A simplified reduced-order model is also developed to rapidly and accurately describe the self-folding physics.An important aspect of self-folding is the management of self-collisions, where different portions of the folding structure contact and then block further folding.A metric is developed to predict collisions and is used together with the reduced-order model to design self-folding structures that lock themselves into stable desired configurations.

View Article: PubMed Central - PubMed

Affiliation: The George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA.

ABSTRACT
Folding is ubiquitous in nature with examples ranging from the formation of cellular components to winged insects. It finds technological applications including packaging of solar cells and space structures, deployable biomedical devices, and self-assembling robots and airbags. Here we demonstrate sequential self-folding structures realized by thermal activation of spatially-variable patterns that are 3D printed with digital shape memory polymers, which are digital materials with different shape memory behaviors. The time-dependent behavior of each polymer allows the temporal sequencing of activation when the structure is subjected to a uniform temperature. This is demonstrated via a series of 3D printed structures that respond rapidly to a thermal stimulus, and self-fold to specified shapes in controlled shape changing sequences. Measurements of the spatial and temporal nature of self-folding structures are in good agreement with the companion finite element simulations. A simplified reduced-order model is also developed to rapidly and accurately describe the self-folding physics. An important aspect of self-folding is the management of self-collisions, where different portions of the folding structure contact and then block further folding. A metric is developed to predict collisions and is used together with the reduced-order model to design self-folding structures that lock themselves into stable desired configurations.

No MeSH data available.