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A variational model for the functional fatigue in polycrystalline shape memory alloys
Author(s) -
Waimann Johanna,
Junker Philipp,
Hackl Klaus
Publication year - 2016
Publication title -
pamm
Language(s) - English
Resource type - Journals
ISSN - 1617-7061
DOI - 10.1002/pamm.201610191
Subject(s) - shape memory alloy , pseudoelasticity , austenite , martensite , dissipation , materials science , diffusionless transformation , crystallite , context (archaeology) , phase (matter) , thermodynamics , yield (engineering) , deformation (meteorology) , mechanics , statistical physics , metallurgy , microstructure , composite material , physics , paleontology , quantum mechanics , biology
Shape memory alloys show a very complex material behavior associated with a diffusionless solid/solid phase transformation between austenite and martensite. Due to the resulting (thermo‐)mechanical properties – namely the effect of pseudoelasticity and pseudoplasticity – they are very promising materials for the current and future technical developments. However, the martensitic phase transformation comes along with a simultaneous plastic deformation and thus, the effect of functional fatigue. We present a variational material model that simulates this effect based on the principle of the minimum of the dissipation potential. We use a combined Voigt/Reuss bound and a coupled dissipation potential to predict the microstructural developments in the polycrystalline material. We present the governing evolution equations for the internal variables and yield functions. In addition, we show some numerical results to prove our model's ability to predict the shape memory alloys' complex inner processes. (© 2016 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)