Architecture? Architected Materials. 3D Printing and Their Applications for Architected Materials. Today s outline

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1 Today s outline 3D Printing and Their Applications for Architected Materials - Introduction of architected materials - Two examples from my research a. Architected materials for enhanced tunability of Prof. Sung Hoon Kang Department of Mechanical Engineering Hopkins Extreme Materials Institute Johns Hopkins University vibration propagation b. Architected materials for reusable and customizable energy absorption May 7, 2015 Greater Baltimore Committee Education and Workforce 1 - Summary & Acknowledgements 2 Architected Materials Architecture? 3 4

2 Experiment Simulation 3 cm Computational Modeling 5 J. Shim, C. Perdigou, E. R. Chen, K. Bertoldi, and P. M. Reis, Proc. Natl. Acad. Sci. USA 109, 5978 (2012). 6 Materials with new properties Lewis Harvard Advanced Manufacturing ρmicrolattice (density) 0.9 mg/cm 3 c.f. ρwater (density) ~ 1000 mg/cm 3 properties previously unavailable Zheng et al., Science 344, 1373 (2014). Fang 7 T. A. Schaedler, A. J. Jacobsen, A. Torrents, A. E. Sorensen, J. Lian, J. R. Greer, L. Valdevit, W. B. Carter, Science 334, 962 (2011) Zheng et al., Science 344, 1373 (2014). 8

3 Materials with desirable properties Examples of reported properties negative Poisson s ratio material (auxetic material) expand in a lateral direction under vertical stretching materials with desirable deformation behaviors negative swelling ratio material Young s Modulus Bulk Modulus Shear Modulus Poisson s Ratio negative incremental stiffness material negative stiffness material need less force (stress) for more deformation (strain) result in the displacement in opposite directions w.r.t the applied force Young's Modulus = Young's Modulus = Young's Modulus = Young's Modulus = Bulk Modulus = Bulk Modulus = Bulk Modulus = Bulk Modulus = Shear Modulus = Shear Modulus = Shear Modulus = Shear Modulus = Poisson's Ratio = Poisson's Ratio = Poisson's Ratio = Poisson's Ratio = K. C. Cheung and N. Gershenfeld, Science 341, 1219 (2013). R. Lotfi, S. Ha, J. V. Carstensen, and J. K. Guest, MRS. Proc. 1662, (2014). 9 R. S. Lakes, Science 235, 1038 (1987). E. B. Duoss et al., Adv. Funct. Mater. 24, 4905 (2014). R. S. Lakes, T. Lee, A. Bersie and Y. C. Wang, Nature 410, 565 (2001). 10 Shoes with architected materials Examples to cover wraps your foot in a lightweight second skin for powerful support & incredible feel mm architected materials for enhanced tunability of vibration propagation architected materials for reusable and customizable energy absorption Dynamic behaviors of architected materials 12

4 Our overall approach Motivation of our study: Designing adaptive cellular materials Inspired by Nature. Venus flytrap Viruses Rational Design Feedback Finite Element Methods Computational Modeling Advanced Manufacturing (3D Printing, etc.) Forterre et al., Nature, nm Baker et al., Microbiol. Mol. Biol. R., 1999 Can we exploit deformation and instabilities to design adaptive cellular materials that tune their shape and properties in response to external stimuli? Sample Characterizations Static/ Dynamic Tests Sample Fabrication 13 StimulusUltralight metallic microlattice T. A. Schaedler et al., Science (2011). Desired set of properties and functionalities Grid-supported membrane for fuel cell M. Tsuchiya et al., Nature Nanotechnology (2011). 14 Harnessing buckling to control the propagation of elastic waves Buckling can be exploited to tune the phononic band gaps of the structure Rational design of geometry A network of connected squares has a single folding mechanism. Deformation/Buckling Expanded Folded In planar networks built from equilateral triangles such as the kagome lattice - the number of folding mechanisms grows with the size of unit cell. (V. Kapko, M.Treacy, M.Thorpe and S.Guest, Proc.R.Soc.A (2009)) Square array of circular holes P. Wang, J. Shim and K. Bertoldi, Physical Review B (2013) Can we enhance the tunability of the system by inducing multiple pattern transformations? 15 S. Shan, S. H. Kang, P. Wang, C. Qu, S. Shian, E. R. Chen and K. Bertoldi, Advanced Functional Materials (2014). 16

5 Computational modeling and experimental verifications of patterns Computational modeling for wave propagation A Experiments Undeformed B 5mm C A B C Material used: Mold Max 60 from Smooth-On Inc. Sample: Fabricated by using 3D printed molds εxx = εxx = εyy = εyy = S. Shan, S. H. Kang, P. Wang, C. Qu, S. Shian, E. R. Chen and K. Bertoldi, Advanced Functional Materials (2014). (ε area = -0.24) (ε area = -0.24) (ε area = -0.24) Experimental demonstration of tuning vibration propagation Potential applications/implications car window that can block noises while allowing air flow? improved sound walls? S. Shan, S. H. Kang, P. Wang, C. Qu, S. Shian, E. R. Chen and K. Bertoldi, Advanced Functional Materials (2014)

6 Examples to cover Energy- absorbing materials and structures are used in various areas of our life mm 20 mm Metal column & cellular material with plastic deformation 0.05 mm Shear load 5mm Epoxy film with multiwalled carbon architected materials for enhanced tunability of vibration propagation architected materials for reusable and customizable energy absorption Dynamic behaviors of architected materials 21 Carbon nanotube and polymer-based composites with viscoelastic dissipation nanotube fillers b 10 µm Nanotube clusters Nanotube clusters Steel plates Axis normal to steel plates J. Suhr, N. Koratkar, P. Keblinski and P. Ajayan, Nature Mater Issues of current approaches Motivation - Irreversible change of microstructures (degradation, limited use) - Strain-rate and/or temperature dependence - Scalable synthesis of materials How can we design scalable energy-absorbing materials/structures that allow repeated uses over a large range of strain rates? 23 24

7 Elastic deformations have been studied for various novel functions. Flexible electronics Controlling elastic wave propagation We can design a minimal system that can trap elastic strain energy by snap- through phenomenon of a beam. D.-H. Kim et al., Proc. Natl. Acad. Sci. USA (2008). Glass bead S. Shan et al., Adv. Funct. Mater. (2014). (a) (b) (c) (d) Approach Engage Lift Stretched (flat surface) High adhesion force Tunable adhesion Reversible Release Un-stretched (ripple surface ) Low adhesion force S. Yang, K. Khare, and P.-C. Lin, Adv. Funct. Mater. (2010) Using numerical simulations, we investigated the range of parameters that allows bistability of a beam. We use computational modeling as design guides. Straight ligament Geometry: L, t, θ Parameters: t/l, θ Numerical simulation ABAQUS CAE Standard/Explicit Element: CPE4R (Plain strain condition) Material model: hyperelastic (Neo-Hookean) Boundary conditions: bottom left: fixed (u1=u2=ur3=0) top right: u1=0 and u2 is progressively increased 27 S. Shan, S. H. Kang, J. Raney, P. Wang, L. Fang, F. Candido, J. Lewis, and K. Bertoldi, under review. ( : equal contribution) 28

8 We verified the phase diagram by 3D printing samples. Exp The fabricated structure could store elastic deformation energy. S. Shan, S. H. Kang, J. Raney, P. Wang, L. Fang, F. Candido, J. Lewis, and K. Bertoldi, Dr. Jordan Raney (Jennifer Lewis Harvard) 29 under review. ( : equal contribution) 30 We also fabricated macroscale samples using 3D printed molds. The measured force- displacement curve showed a good agreement with simulation data allowing a modular design. Macro scale Molds were printed by Objet Connex 500 Replica were made using silicone rubber (Mold-Max 10 from Smooth-On, Inc.) Limit: Thickness > 1mm Slightly tapered Mold Max S. Shan, S. H. Kang, J. Raney, P. Wang, L. Fang, F. Candido, J. Lewis, and K. Bertoldi, under review. ( : equal contribution) 3

9 We characterized energy absorption behaviors by measuring acceleration amplitudes from free drop tests. We also tested the energy absorption capability by egg drop tests. Control Multistable 50-70% reduction in accelerometer peak acceleration amplitudes and impact S. Shan, S. H. Kang, J. Raney, P. Wang, L. Fang, F. Candido, J. Lewis, and K. Bertoldi, played x50 slower than real time under review. ( : equal contribution) Architected materials for absorbing energy Energy absorption by locking in energy Reversiblity Strain-rate independence Scalability Modularity Overall summary Architected materials provide new opportunities for engineering functions by harnessing deformation based on computational modeling and 3D printing. Reversible bumpers with better protection of pedestrians? Protective cases for sensitive equipments? Position controllers for soft robots? Reversible Energy Absorption Structures/Materials, S. H. Kang, K. Bertoldi, S. Shan, U.S. Provisional Patent Application No. 61/983,782 filed in April

10 Acknowledgements Prof. Katia Bertoldi Mr. Sicong Shan (Bertoldi group) Prof. Jennifer Lewis Dr. Jordan Raney (Lewis group) Mr. Pai Wang (Bertoldi group) Mr. Lichen Fang (Bertoldi group) 37