Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi: Simulations vs. Experiment

Sivom Manchiraju; Darrell Gaydosh; Othmane Benafan; Ronald Noebe; Raj Vaidyanathan; Peter M Anderson

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NASA NTRS · 20110016180

Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi: Simulations vs. Experiment

Sivom Manchiraju·Darrell Gaydosh·Othmane Benafan·Ronald Noebe·Raj Vaidyanathan·Peter M Anderson

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Abstract

A recent microstructure-based FEM model that couples crystal-based plasticity, the B2<-> MB190 phase transformation and anisotropic elasticity at the grain scale is calibrated to recent data for polycrystalline NiTi (49.9 at.% Ni). Inputs include anisotropic elastic properties, texture and differential scanning calorimetry data, as well as a subset of recent isothermal deformation and load-biased thermal cycling data. The model is assessed against additional experimental data. Several experimental trends are captured - in particular, the transformation strain during thermal cycling monotonically increases and reaches a peak with increasing bias stress. This is achieved, in part, by modifying the martensite hardening matrix proposed by Patoor et al. [Patoor E, Eberhardt A, Berveiller M. J Phys IV 1996;6:277]. Some experimental trends are underestimated - in particular, the ratcheting of macrostrain during thermal cycling. This may reflect a model limitation that transformation-plasticity coupling is captured on a coarse (grain) scale but not on a fine (martensitic plate) scale.

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Phase Transformations Martensite Elastic Properties Anisotropy Plastic Deformation Hysteresis Dimensional Stability Finite Element Thermal Cycling Shape Memory Alloys

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Sivom Manchiraju, Darrell Gaydosh, Othmane Benafan, Ronald Noebe, Raj Vaidyanathan, Peter M Anderson. 2011-08-01. Thermal Cycling and Isothermal Deformation Response of Polycrystalline NiTi: Simulations vs. Experiment. https://ntrs.nasa.gov/citations/20110016180

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Anisotropy subject Dimensional Stability subject Elastic Properties subject Finite Element subject Hysteresis subject Martensite subject Phase Transformations subject Plastic Deformation subject

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