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Bidirectional and biaxial curving of thermoresponsive bilayer plates with soft and stiff segments
- Source :
- Extreme Mechanics Letters. 16:6-12
- Publication Year :
- 2017
- Publisher :
- Elsevier BV, 2017.
-
Abstract
- Curved bilayer plates with soft and stiff segments are widely observed in nature, such as plant cell walls, insect exoskeletons and reptile skins. We report an unusual biaxial and bidirectional bending of microfabricated bilayer plates composed of a swellable, photopolymerized poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) layer and a regular array of SU-8, a stiff, non-swellable epoxy. Hydrogels such as pNIPAM-AAc exhibit large and reversible swelling in water in response to a temperature change through the lower critical solution temperature (LCST). The stimuli responsive behavior was harnessed in the composite structure containing materials with mismatched swelling and elastic properties to produce actuation and mechanical motion. The structure undergoes reversible bending along two different axes in response to a temperature cycle through the LCST. Cooling the patterned bilayer structure leads to bending upwards about one axis, while heating leads to bending downwards about a different axis, 9 0 o from the first. To understand the mechanism of this biaxial bending behavior, we developed a finite element model of the patterned bilayer structure. A constitutive model that combined the hyperelastic and swelling behavior was used to describe the thermoresponsive hydrogel. The model was applied to investigate the effects of geometric factors of the patterned bilayer on the bending behavior of the composite structure.
- Subjects :
- Materials science
Mechanical Engineering
Bilayer
Constitutive equation
Bioengineering
02 engineering and technology
Epoxy
Bending
010402 general chemistry
021001 nanoscience & nanotechnology
01 natural sciences
Lower critical solution temperature
0104 chemical sciences
Mechanics of Materials
visual_art
Hyperelastic material
Self-healing hydrogels
visual_art.visual_art_medium
medicine
Chemical Engineering (miscellaneous)
Composite material
Swelling
medicine.symptom
0210 nano-technology
Engineering (miscellaneous)
Subjects
Details
- ISSN :
- 23524316
- Volume :
- 16
- Database :
- OpenAIRE
- Journal :
- Extreme Mechanics Letters
- Accession number :
- edsair.doi...........36a76e5c2487e8f15844a939be3c95b6