Functional and structural fatigue of NiTi shape memory alloy

Cyclic loading induced evolution in mechanical properties leading to fatigue failure is studied and characterized by investigating deformation processes activated in particular – defined microstructures. Activation of deformation processes investigated ex-situ using electron microscopy are correlated with cyclic evolution of various parameters such as unrecovered strain, el. resistance, surface strain localization, mechanical hysteresis, dissipated heat, temperature [1-4]..

Description

Theory and experiment allowing to evaluate irreversible deformation accompanying stress-induced martensitic transformation independently for forward transformation under load and back transformation under load. [4]

[1]P. Sedmák, P. Šittner, J. Pilch, C. Curfs: Instability of cyclic superelastic deformation of NiTi investigated by synchrotron X-ray diffraction, Acta Materialia 94 (2015) 257-270

[2]O. Tyc, J. Pilch, P. Šittner: Fatigue of superelastic NiTi wires with different plateau strain Procedia Structural Integrity 2 (2016) 1489-1496.

[3]E. Alarcon, L. Heller, S. Arbab Chirania, P. Šittner, J. Kopeček, L. Saint-Sulpice, S. Calloch
Fatigue performance of superelastic NiTi near stress-induced martensitic transformation
Int. J. Fatigue 95 (2017) 76 – 89.

[4]L Heller, H Seiner, P Šittner, P Sedlák, O Tyc, L Kadeřávek, On the plastic deformation accompanying cyclic martensitic transformation in thermomechanically loaded NiTi, International Journal of Plasticity 111(2018)53-71