The document discusses constitutive modeling and simulation of shape memory polymers. It begins with an introduction to shape memory materials and how shape memory polymers work. It then discusses developing a thermo-mechanical framework for modeling glassy shape memory polymers and crystalline shape memory polymers. The document outlines simulations conducted including modeling the shape memory cycle of a glassy polymer under uniaxial deformation and the torsion of a polymer cylinder. It concludes with discussing future work such as further developing the glassy polymer model and solving inhomogeneous boundary value problems.

1. Constitutive Modeling and Simulation of Shape Memory Polymers Defense Proposal ADVISOR: DR I.J. RAO DATE : 11/17/2008 MAHESH KHANOLKAR

5. How Shape Memory Polymers Work Original: Chemical Cross-Links Temporary: Glassy Phase Lendlein et al. Original: Crystalline Hard domains (Physical cross-links) Temporary: Crystallites Original: Chemical Cross-Links Temporary: Crystallites

7. Shape Memory Polymers Representative Application Biodegradable Shape Memory Polymer for Suturing wounds. (Langer 2002)

8. Shape Memory Polymers Representative Application Time series photographs that show the recovery of a shape-memory tube. (a)- (f) Start to finish of the process takes a total of 10 s at 50°C (Marc Behl et al 2007).

10. Shape Memory Mechanism in CSMP’s Deform Cool Unload Heat Amorphous polymer Cross-link Crystallite Legend Melting Crystallization T > T r T < T r State 1 State 4 State 2 State 3 Stretch Nominal Stress 1 2 3 4

11. Shape Memory Mechanism in GSMP’s Deform Cool Unload Heat Amorphous polymer Cross-link Glassy polymer Legend Glass Transition T > T r T < T r State 1 State 4 State 2 State 3 Stretch Nominal Stress 1 2 3 4

16. Modeling - Natural Configurations Natural configurations associate with a viscoelastic melt

21. Modeling – Glassy SMP (Mixture of rubbery and glassy phase) Natural Configurations associated with the glassy-rubbery phase solid phase mixture

24. Modeling – Glassy SMP Cycle Stress–strain–temperature diagram illustrating the thermo mechanical behavior of a shape memory polymer under different strain/stress constraint conditions

25. Simulation and Results (Uniaxial Deformation Cycle GSMP) Stress vs Strain for the complete SMP Cycle T L (K) 273 T g (K) 343 T H (K) 358 (Mpa) 8.8 MPa (Mpa) 750 MPa

26. Simulation and Results (Uniaxial Deformation Cycle GSMP) Stress vs Temperature

27. Simulation and Results (Uniaxial Deformation Cycle GSMP) Stress vs Strain plot (Yiping Liu et al, 2005)

29. Simulation and Results (Uniaxial Deformation Cycle GSMP) Effect of Nanoreinforcemnts Elastic moduli of the SMP and SMP composite at 26 and 118°C (Yiping Liu et al 2003) .

30. Simulation and Results (Uniaxial Deformation Cycle GSMP) Effect of Nanoreinforcemnts Stress vs Strain Above the glass transition

31. Torsion of a Cylinder Undeformed Cylinder Deformation after applying Torsion Motion: Deformation gradient: M (in sec -2 ) (MPa) (MPa) 0.33 120 1200 0.00007 0.256 50

32. Simulation and Results: Torsion of a Cylinder Moment vs Time (Torsion of a cylinder)

33. Simulation and Results: Torsion of a Cylinder Moment vs Shear (Torsion of a cylinder)

34. Simulation and Results: Torsion of a Cylinder Shear vs Time (Torsion of a cylinder)

36. Simulation and Results: Large Deformation on a single cubic element using UMAT (ABAQUS) Applied load to the Element

37. Simulation and Results: Large Deformation on a single cubic element using UMAT (ABAQUS) Step 1 Large Deformation on the single element

38. Simulation and Results: Large Deformation on a single cubic element using UMAT (ABAQUS) Step 2 Constraining the element to retain its temporary shape

39. Simulation and Results: Large Deformation on a single cubic element using UMAT (ABAQUS) Step 3 Removing load – Small amount of strain recovery

40. Simulation and Results: Large Deformation on a single cubic element using UMAT (ABAQUS) Step 4 Back to Original Shape