Biomimetic Surfaces and Interfaces for Multifunctional Structures - PowerPoint PPT Presentation

Biomimetic Surfaces and Interfaces for Multifunctional Structures ASHKAN VAZIRI Department of Mechanical and Industrial Engineering Northeastern University Surface Engineering of Polymers Joints with non-flat interfaces Threat-Resistant Multifunctional Novel cellular Structures with Structural Systems Tailorable Properties hpmsl.neu.edu

Surface Patterning and Engineering Moon et al PNAS 2007 Moon et al Scripta Mater. 2007 Collaborators: John W. Hutchinson-Harvard Moon et al, Scripta Mater. 2009 Lahmawan et al, Langmuir 2009 Myoung-Woon Moon (KIST, South Korea) K. H. Oh (SNU, South Korea)  Plasma treatment: common technique.  Focused ion beam: localized and precise patterning.

Polymer Surface Wrinkles: Prestretching + Surface Treatment 5 m m Moon and Vaziri , Scripta Materialia, 2009

Biaxial loading and Multi-step Plasma Treatment Biaxial Loading Multistep plasma treatment

Controlled Wrinkle Patterns on Polymers Exposed to Ion beam 10 micron Straight Herringbone 400 nm 400 nm Hierarchical Complex patterns Moon et al, PNAS, 2007 Moon et al, Scripta Materialia, 2007 Moon et al., Soft Matter, 2010

BioInspired Design- Gecko’s foot Height=30 m m, diameter = 8 m m, spacing= 10 m m Moon et al, Soft Matter, 2010 (most downloaded article of Soft Matter for 2 months)

BioInspired Design- Gecko’s foot The ion beam treatment was made with argon discharge at an anode voltage of 1 keV, a bias voltage of 600 V and a pressure of 0.49 Pa.

BioInspired Design- Gecko’s foot

Indium Nanowires Synthesized at Ultra-Fast Rate 5 micron Voltage : 10 kV Current : 3 pA Irradiated area : 30 μ m Χ 25 μ m Current density : 400 nA/cm 2 Growth rate : 300 nm/min Oh et al, Advanced Mat., 2008

Functional Networks of Nanowires Functional Networks of Nanowires Maskless Patterning Method 5 micron

Joints with non-flat interfaces Ashrafi et al., Int. J. Adhesion and Adhesives, 2012

Joints with non-flat interfaces Ashrafi et al., Int. J. Adhesion and Adhesives, 2012

Joints with non-flat interfaces Chung et al., in prep.

Joints with non-flat interfaces

Joints with non-flat interfaces

Low Density Cellular Structures  Heterogeneous and Functionally graded and hybrid cellular structures  Fractal – appearing hierarchical honeycombs  Ultra lightweight composite lattices

Dynamic Crushing of Functionally Graded Cellular Structures

Hierarchical Honeycombs g = c / L Theoretical model: 1 The normalized stiffness is independent of the honeycomb relative density. g = b / L 2 Ajdari et al., IJSS, 2012

Hierarchical Honeycombs Jahromi et al., submitted

Hierarchical Honeycombs – One order hierarchy

Hierarchical Honeycombs Oftadeh et al., in prep

Hierarchical Honeycombs

Low density composite lattices – Core manufacturing Xiong et al., Composite Structures, 2010 Xiong et al, Acta Materialia, 2011

Low density composite lattices – Core crushing

Low density composite lattices – Failure Mechanisms Xiong et al., Composite part B, 2011 Xiong et al., Acta Materialia, 2012 Xiong et al., Acta Materialia 2012

Threat-Resistant Sandwich-walled structures Folded plate (Corrugated) Square honeycomb h f H L h f B t Explosion Plastic hinge Initial state   max max Support structure Face Core stretching crushing Vaziri et al, JoMMS, 2006; Vaziri et al, JoMMS, 2007 ; Vaziri and Hutchinson, IJSS, 2008

Failure-Map for Square Honeycomb Sandwich Panels M   = I /( / ) 0.272 Y  f = 0.02 c c  f = 0.04 c c 0.37 0.33  f = 0.06 0.29 c c 0.25 0.21  core failure f = 0.08 c c 0.17 face(s) failure total failure 0.13 0.02 0.03 0.04 0.05 0.06 0.07 0.08  c Vaziri, Xue, Hutchinson, JoMMS, 2007

Threat-Resistant Sandwich-Walled Structures

Publications (YIP FY 2010) 1. Mechanical Behavior of Carbon Fiber Composite Lattice Core Sandwich Panels Fabricated by Laser Cutting J. Xiong, L. Ma, A. Vaziri, J. Yang & L. Wu, Acta Materialia , 2012, in press. 2. Hierarchical Honeycombs with Tailorable Properties A. Ajdari, B. Haghpanah, J. Papadopoulos, H. Nayeb-Hashemi & A. Vaziri, Int. J. Solids and Structures , 2012, 49, pp. 1413 – 141. 3. Mechanical properties of open-cell rhombic dodecahedron cellular structures S. Babaee, B. Haghpanah, A. Ajdari, H. Nayeb-Hashemi & A. Vaziri, Acta Materialia , 2012, 60, pp. 2873 – 2885. 4. Shear and bending performance of carbon fiber composite sandwich panels with pyramidal truss cores J. Xiong, L. Ma, S. Pan, L. Wu, J. Papadopoulos & A. Vaziri, Acta Materialia , 2012, 60, pp. 1455-1466. 5. Compression and impact testing of two-layer composite pyramidal-core sandwich panels J. Xiong, A. Vaziri, L. Ma, J. Papadopoulos & L. Wu , Composite Structures , 2012, 94, pp. 793-801. 6. Adhesively bonded single lap joints with non-flat interfaces M. Ashrafi, A. Ajdari, N. Rahbar, J. Papadopoulos, H. Nayeb-Hashemi & A. Vaziri, International Journal of Adhesion and Adhesives , 2012, 32, pp. 46-52. 7. Effect of Processing Variables and Fiber Reinforcement on the Mechanical Properties of Wood Plastic Composites M. Ashrafi, A. Vaziri & H. Nayeb-Hashemi, Journal of Reinforced Plastics and Composites , 2011, 30, pp. 1939-1945. 8. Dynamic crushing and energy absorption of regular, irregular and functionally graded cellular structures A. Ajdari, H. Nayeb-Hashemi,& A. Vaziri, Int. J. Solids and Structures , 2011, 48, pp. 506-516. 9. High aspect ratio wrinkles on soft polymer Sk. Faruque Ahmed, G. Nho, K. R. Lee, A. Vaziri & M. W. Moon, Soft Matter , 2010, 6, 5709-5714 10. Tilted Janus Polymer Pillars M. W. Moon, T. G. Cha, K. R. Lee, A. Vaziri & H. Y. Kim, Soft Matter , 2010, 6, 3924-3929.

Acknowledgement Funding and Support AFOSR YIP award CMMI DHS NSF CAREER Collaborators John W. Hutchinson, Harvard Hamid Nayeb-Hashemi, Northeastern Horacio D. Espinosa, Northwestern Vikram S. Deshpande, University of Cambridge Group Members http://www.hpmsl.neu.edu/people/index.html

Support: NSF – CMMI (2007-2008) College of Engineering, Northeastern University (2008 – present) 2010 AFOSR Young Investigator Award FM Global (2008 - present)

Surface structures to relax strain energy Wrinkle ( LDPE) Wrinkle (PDMS ) Hard skin soft substrate Hard skin Buckle (PP ) Delamination (PMMA) hard substrate Hard skin hard substrate Surface roughening : PI Pore (PMMA)

Instability of Wrinkles in technology Moon et al PNAS 2007 Lahmawan et al, Langmuir 2009 Moon et al, Scripta Mater. 2009 www.ilounge.com In this talk ,  1-D multi-step plasma treatment: common technique for patterning on polymer surface.  2-D wrinkled hard skins: localized and precise patterning on polymers.

Wrinkling Patterns in Skin 200nm 100 m m 50 m m 100 m m 1mm Skin thickness=5nm E=100MPa Substrate E=1MPa 100nm Efimenko et al., 2005 Rizzeri et al., 2006 Vaziri et al., in prep.

Surface Wrinkles Created by Focused Ion Beam Exposed to Ion beam Polymer: poly(dimethylsiloxane, PDMS) Elastomer vs cross linker = 15:1 cured at 80 ℃ 1hour E modulus: 1-10MPa FIB (HRFIB/SEM, nova200, FEI) 30KeV, 1pA~20nA. Moon et al., PNAS (2007) Moon et al., Scripta Materialia (2009)

Wrinkles Morphologies

Wrinkles Morphologies

Structure-Function Paradigm in Living Cells Understanding how living cells migrate, differentiate, interact with each other and in general function entails resolving mechanics at various spatial and temporal scales. Role of surface topology on the behavior of NIH-3T3 cells Flat substrate 10 m m Wrinkled substrate Wavelength= 1 micron Wrinkling pattern direction Moon, Khademhosseini & Vaziri, in prep.

Experimental Techniques for Probing Cell Mechanics

Computational Approaches in Cell and Biomolecular Mechanics Vaziri & Gopinath, 2007

Power-law Rheology of Cytoskeleton-MTC Torque 1 m m m Displacement 0.01Hz Experimental data 0.03Hz HASM cells 0.1Hz 0.75Hz 10Hz 1000Hz Vaziri, Xue, Kamm & Mofrad, 2007

Localized Structures: Formation and Evolution Formation Evolution

Mechanics of an Isolated Nucleus Inner/outer membrane stiffness Indentation force, nN K b =10 -19 Pa Indentation depth, nm Nucleoplasm stiffness Indentation force, nN E=10 Pa Indentation depth, nm Vaziri, Lee & Mofrad, 2006

Joints with non-flat interfaces

Joints with non-flat interfaces

Role of irregularity Babee et al, Acta Materialia, 2012

3D Sculpting Moon et al, Nanotechnology, 2009 Moon et al, Surface Coating and Technology, 2008

Dynamic Crushing of Regular Hexagonal – Deformation Modes Ajdari, Nayeb-Hashemi & Vaziri , IJSS, 2011

Dynamic Crushing of Voronoi Structure