MecaWet group. Étienne Reyssat. Benoît Roman. Emmanuel Siefert. Hadrien Bense. Étienne Guyon. Miguel Trejo. Marie Tani.

Transcription

1 MecaWet group Benoît Roman Étienne Reyssat Hadrien Bense Emmanuel Siefert Miguel Trejo Ludovic Keiser Marie Tani Étienne Guyon

2 Actuated Origami spontaneous? web-japan.org/kidsweb

3 Origami in Nature video.nationalgeographic.com

4 Outlines - Capillary forces - Swelling - Electric field - Pneumatic actuation

5 Wrapping a solid sphere solid? with Jérémy Hure Hure et al. PRL (2011)

6 no contact contact

7 widest adhering patch?

8 Physical ingredients: Bending L R w h U adh Lw (surface tension) wrapping if : R>L BC s Eh 3 U bend Eh3 R 2 Lw

9 but also stretching a a if radius preserved, perimeter in excess R a r>a if perimeter preserved, radius stretched R

10 h Balance stretching / adhesion a 1/4 Eh a [mm] stretching: R (a/r) a U stretch Eha 2 2 adhesion: U adh a 2 50 h = 50 µm h = 30 µm h = 15 µm widest adhering patch: /4 a max R for R L Eh EB R [mm]

11 Shell on a sphere h a R with Maïka Saint-Jean, Hadrien Bense, Marie Tani

12 Shell on a sphere Shallow shell limit h a R stretching : adhesion: a R U stretch Eha 2 2 U adh a (R/ ) 2 widest adhering shell : a max R Eh 1/4 1 p 1 (R/ )2 for R L EB

13 Shell on a sphere Shallow shell limit a max R Eh 1/4 h a shell on the sphere shell inside the sphere p 1 (R/ )2 8 R R/ 3 4

14 Open questions: a > amax? <R >R

15 Outlines - Capillary forces - Swelling - Electric field - Pneumatic actuation

16 Swelling bilayers residual solvant " 0 natural curvature: h R 0 R 0 h/" 0

17 drying easter lily pollen grain Bilayer shells bilayer elastomer shell E. Katifori, J. Dumais et al. (2010) Miguel Trejo, Matteo Pezzulla, Doug Holmes, Étienne Couturier Open question: isometric transformation?

18 Drying slice of fresh wood vimeo.com/ Aurélie Vissac (Amàco) & Pascal Oudet

19 Non-uniform swelling/growth fast growth slow growth Dervaux & Ben Amar PRL (2008)

20 Non-uniform swelling/growth Eran Sharon s group: swelling gradients Y. Klein, E. Efrati, E. Sharon, Science (2007)

21 Non-uniform swelling/growth Ryan Hayward s group: half tone gel lithography J. Kim et al., Science (2012)

22 Outlines - Capillary forces - Swelling - Electric field - Pneumatic actuation

23 Electro-active polymers elastomer carbon black powder with Hadrien Bense

24 Engineering applications? a b Pelrine et al., Science (2000) Kofod & Wirges, APL (2007) Fig. 3. Electrode voltage,, and charge, Q, of the EEC for three energy conversion cycles (a). Work-conjugate voltage/charge graph showing three energy conversion cycles of the EEC (b). X. Suo s group Huang & al., APL (2012) Carpi & al., Adv. Funct. Mater (2011) Fig. 4. The EEC mounted to the custom made water-column volumeter used for pressure/volume-measurements. Peter & al., EML (2015)

25 Target strain U elec = 1 2 CV 2 = 1 2 " 0" r S h V 2 elastomer p elec = 1 = 1 2 " 0" r V h elec = 1 2 " V 2 0" r h rr = = 2 elec /h e rr = e = e zz 1+2 = e 0 = 1 2E " 0" r V h 2 see also Pelrine et al. Science (2000)

26 Experimental system: a single active patch b. rigid frame V air cushion h image manip avec ambage E ~ 250 kpa h ~ 200 µm Vmax ~ 5 kv

27 Out of plane buckling A/a e 0 /e c 0.14 w (m) x A r (m) Numerical calculations using Föppl-Von Karman equations

28 Open questions: secondary buckling a = 3 cm, V = 3 kv

29 Open questions: annuli W W W

30 Open questions: free membranes 1cm Front view, 0 V bilayer Side view, 5kV also with Bruno Sécordel