Advanced Materials Laboratory

1. Advanced Materials Laboratory Professor Cate Brinson Current Students/Postdocs : Tao Bai, Debbie Burton, Frank Fisher, Xiujie Gao, Zhu He, Huanlong Li, Ram Ramanathan, Hua Liu • Recent PhD’s: • Bradshaw (now at University of Louisville) • Huang (now at Ford) • Bekker (now at Tumbleweed Software) Northwestern University

2. Solid Mechanics, Material Characterization, Nano-/Micro-/Continuum-mechanics • Questions: • Why do materials behave the way they do? • How can we describe how the materials behave, dependent on environment and loading conditions? • Can we predict how the materials will behave as a part of structures? • Tools: • physics of materials at nano - macro length scales • molecular, crystallographic characterization • extensions to basic concepts of elasticity • mathematical modeling • computer simulations • experimental characterization Northwestern University

3. Overview • Advanced Material Systems: Polymers Shape Memory Alloys • PMCs Other Advanced Matls. • Link nano/microscale effects to macroscopic behavior Phase transformations Molecular Structure Stiffness actuation strain • Address coupling between environment and material response s e DT i c E • Goals • Better understanding of advanced material systems • Better models of complex constitutive response of advanced materials • Enable better and novel design of and with materials Northwestern University

4. Examples of work in my group • Polymers & PMCs • Effective properties • Interphase effects • Aging/durability • Nano-reinforced polymers • Shape Memory Alloy (SMA) behavior • Micromechanics • Microscale experiments • Ti Foam Materials for bone implants • Analytical and FE modeling • Biological and mechanical testing Northwestern University

5. Degradation of Polymer Wiring Insulation } • Temperature variations • Mechanical stress/abrasion • Environmental agents Aging Embrittlement and damage Loss of dielectric/insulating properties Northwestern University

6. Assessment of Degradation with IS • Monitor changes in dielectric constant with aging aging Degraded kapton spectra Northwestern University

7. Princeton UCSB UNC ICASE NC A&T Northwestern Nano-reinforced Polymers • Bridge gap in meso-micro modeling • Experiments on polymers with nano-reinforcements nanomechanics Northwestern University

8. FE unit cell of single NT NT curvature distribution Multiphase micromechanics (Mori Tanaka) model Nanotube reinforced polymer micrograph Hybrid Nanomechanical Modeling • Finite element analysis of unit cell • Micromechanics to account for NT curvature distribution • Show effect of curvature on composite modulus Northwestern University

9. 2% MWNT in PC (RPI), Tref =150 C test range NRP Viscoelastic Property Experiments • DMA testing on bulk samples • Analysis to obtain relaxation spectra • Significant impact of NTs onspectra Northwestern University

10. T s Shape Memory Alloys - Mechanical Behavior • “Smart Material” • Transformation between crystal structures martensite austenite • Large stresses/strains • Deformation controllable, recoverable s, T Northwestern University

11. Shape Memory Alloys - Applications • • medical • connectors/fasteners • MEMS devices • shape control • frequency control • damage control Bubble actuator Micro-cantilever Medical devices Northwestern University

12. Substructure of Martensite submicron scale 1m Micron scale atomic scale Northwestern University martensite parent

13. SMA Constitutive Modeling • Phenomenological • Kinetic Law • Micromechanics • Scale appropriately crystallographic strains • Combine energy, thermo, micromechanics Compatible variants Transforming inclusions Northwestern University

14. SMA Application and Modeling NASA adaptive stiffening, dynamic response control Composite Beam, Embedded SMA wires, Clamped at ends Northwestern University

15. MV Model - Orientation Dependence • Data Shield, CuAlNi single crystal • Simplified Multivariant Model with anisotropy for CuAlNi • Two parameters “fit” for one curve only (FC, B fit to T3) T3 T2 T1 Northwestern University

16. SMA Recent Experimental Studies • Single crystal CuAlNi & Polycrystal NiTi experiments • Optical Microscopy • SEM • EBSD • All with in situ loading • Experiments designed to provide key modeling information Northwestern University

17. SEM Experimental Set-Up Northwestern University

18. SEM Image Showing Habit Plane, Twins • SEM image at 2000x • Uniaxial loading • Variant ID possible when habit plane and twin plane visible Northwestern University

19. Test8 Optical Microscopy - NiTi NiTi Polycrystal • Identify variants within grains • Characterize evolution with cycles, strain rate 10-4m Northwestern University

20. Characterization of Ti foams for Biological Implants • Finite element modeling, mechanical testing, biological cell growth studies • Collaborative with faculty in Materials Science, Medical School • Solid implants: stiffness mismatch, poor adhesion • Examine mechanical and biological compatibility of Ti foams with bone Northwestern University

21. Characterization of Ti foams for Biological Implants • Look at effect of pore morphology on effective properties, local stress states • Finite element modeling, micromechanics, mechanical testing, biological cell growth studies • Collaborative with faculty in Materials Science, Medical School Northwestern University

22. Open Positions All potentially within 1 year: • LANL opportunity for US citizen in SMA area • NASA SMA computational modeling and structural design • NSF polymernanotechnology - collaborative with ChE and Mat Sci Northwestern University

23. Northwestern University

24. Princeton UCSB UNC ICASE NC A&T Northwestern Northwestern University