Berlin 2012 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 9: Biopolymers and Biomaterials (joint session with BP)
CPP 9.12: Talk
Tuesday, March 27, 2012, 12:45–13:00, H 1058
Assessment of swelling driven actuation in a two-phase cellular material — •Lorenzo Guiducci1, Yves J. M. Brechet2, Peter Fratzl1, and John W. C. Dunlop1 — 1Max Planck Institute of Colloids and Interfaces, Department of Biomaterials, Am Mühlenberg 1, Science Park Golm, Potsdam, Germany — 2SIMaP-Grenoble Institute of Technology, Saint Martin d'Hères, France
Natural systems that are able to actuate -that is, generate stress/strain- have recently drawn the attention of scientific community. Examples include the seed dispersal unit of the wild wheat and stork's bill awn, which are able to crawl on the ground following the daily humidity cycle and the hydro-actuated unfolding of the ice-plant seed capsule.
In natural actuators, the extent of max elongation/forces depends on underlying microstructure, and swelling properties of the constituents: here we present a finite element (FE) simulation study that aims to assess the actuation performance -eigenstrains and effective stiffness at a certain swelling level- of an ideal two-phase cellular material. The eigenstrains assessment is rigorously performed simulating a tessellation of the bidimensional space with given unit cell. As observed in preliminary simulations of a finite patch of material with free boundaries, the resulting two-phase material deforms in a highly anisotropic way. For each value of swelling pressure, we get an equilibrated configuration of the unit cell that becomes the starting point for the calculation of the effective mechanical properties. Finally, we show that the FE results can be understood in terms of a simpler lattice spring model.