Non-Local Modeling on Macroscopic Domain Patterns in Phase Transformation of NiTi Tubes
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Recent experiments revealed many new phenomena of the macroscopic domain patterns in the stress-induced phase transformation of a superelastic polycrystalline NiTi tube during tensile loading. The new phenomena include deformation instability with the formation of a helical domain, domain topology transition from helix to cylinder, domain-front branching and loading-path dependence of domain patterns. In this paper, we model the polycrystal as an elastic continuum with nonconvex strain energy and adopt the non-local strain gradient energy to account for the energy of the diffusive domain front. We simulate the equilibrium domain patterns and their evolution in the tubes under tensile loading by a non-local Finite Element Method (FEM). It is revealed that the observed loading-path dependence and topology transition of domain patterns are due to the thermodynamic metastability of the tube system. The computation also shows that the tube-wall thickness has a significant effect on the domain patterns: with fixed material properties and interfacial energy density, a large tube-wall thickness leads to a long and slim helical domain and a severe branching of the cylindrical-domain front.
Key wordsmartensitic phase transition macroscopic domain patterns NiTi polycrystalline tubes non-local and nonconvex elasticity tube-wall thickness effect metastability and instability
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- Bhattacharya, K., Microstructure of Martensite. Oxford University Press, 2003.Google Scholar
- Reddy, J.N., Theory and Analysis of Elastic Plates and Shells, (2nd edn). CRC Press, 2007.Google Scholar
- Ugural, A.C., Stresses in plates and shells, 2nd edn. McGraw-Hill International Editions, 1999.Google Scholar
- Zienkiewicz, O.C. and Taylor, R.L., The Finite Element Method. Butterworth-Heinemann, 2000.Google Scholar
- Li, Z.Q., Experimental Investigation on Phase Transformation of Superelastic NiTi Microtubes. PhD thesis, Hong Kong University of Science and Technology, 2002.Google Scholar
- Shaw, J.A. and Kyriakides, S., Initiation and propagation of localized deformation in elasto-plastic strips under uniaxial tension. International Journal of Plasticity, 1998, 43: 837–871.Google Scholar