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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) Glass transition temperatures of the seven digital SMPs used for hinge materials; the inset shows a schematic view of the folding of an SMP hinge; (b) folding time of hinges to obtain 98% recovery ratio at various recovery temperatures.
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f1: (a) Glass transition temperatures of the seven digital SMPs used for hinge materials; the inset shows a schematic view of the folding of an SMP hinge; (b) folding time of hinges to obtain 98% recovery ratio at various recovery temperatures.

Mentions: Hinges designed with digital SMPs with specified thermomechanical behaviors, especially recovery, are the key element of sequentially self-folding structures (shown in the inset of Fig. 1a). We design, fabricate, and test hinges using seven different digital SMPs. We use H-i (i = 1, 2, 3 …7) to represent the i-th hinge material and the hinges all have a thickness of 0.8 mm and a width of 6 mm. The glass transition temperatures (Tgs, see the Method for details) of these hinge materials are shown in Fig. 1a. The shape memory behavior of the hinges, including shape fixity and shape recovery, is controlled by the applied mechanical and thermal-temporal programming and recovery conditions. However, different programming methods can lead to the same recovery profile and fixity47 and we exploit this in the design of hinges. To understand the basic hinge behavior we consider a hinge printed with an initial angle of θ = 90° and then programmed (by bending at TH = 90 °C) to assume a temporary flat state (θ = 180°), which corresponds to a shape fixity of 100%. Then we recover the hinges to their original shape (θ = 90°) by heating them in a constant temperature bath, during which we monitor the recovery of the hinges as a function of time. We quantify the shape recovery with the angular recovery ratio (Rr):


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) Glass transition temperatures of the seven digital SMPs used for hinge materials; the inset shows a schematic view of the folding of an SMP hinge; (b) folding time of hinges to obtain 98% recovery ratio at various recovery temperatures.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f1: (a) Glass transition temperatures of the seven digital SMPs used for hinge materials; the inset shows a schematic view of the folding of an SMP hinge; (b) folding time of hinges to obtain 98% recovery ratio at various recovery temperatures.
Mentions: Hinges designed with digital SMPs with specified thermomechanical behaviors, especially recovery, are the key element of sequentially self-folding structures (shown in the inset of Fig. 1a). We design, fabricate, and test hinges using seven different digital SMPs. We use H-i (i = 1, 2, 3 …7) to represent the i-th hinge material and the hinges all have a thickness of 0.8 mm and a width of 6 mm. The glass transition temperatures (Tgs, see the Method for details) of these hinge materials are shown in Fig. 1a. The shape memory behavior of the hinges, including shape fixity and shape recovery, is controlled by the applied mechanical and thermal-temporal programming and recovery conditions. However, different programming methods can lead to the same recovery profile and fixity47 and we exploit this in the design of hinges. To understand the basic hinge behavior we consider a hinge printed with an initial angle of θ = 90° and then programmed (by bending at TH = 90 °C) to assume a temporary flat state (θ = 180°), which corresponds to a shape fixity of 100%. Then we recover the hinges to their original shape (θ = 90°) by heating them in a constant temperature bath, during which we monitor the recovery of the hinges as a function of time. We quantify the shape recovery with the angular recovery ratio (Rr):

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.