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Thermomechanically coupled modelling of shape memory alloys in the framework of large strains
Author(s) -
Christ Daniel,
Reese Stefanie
Publication year - 2008
Publication title -
gamm‐mitteilungen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.239
H-Index - 18
eISSN - 1522-2608
pISSN - 0936-7195
DOI - 10.1002/gamm.200890010
Subject(s) - pseudoelasticity , shape memory alloy , sma* , materials science , diffusionless transformation , martensite , finite element method , deformation (meteorology) , transformation (genetics) , constitutive equation , compression (physics) , coupling (piping) , phase (matter) , nickel titanium , mechanics , structural engineering , computer science , microstructure , composite material , engineering , physics , algorithm , biochemistry , chemistry , quantum mechanics , gene
In the present work we propose a new thermomechanically coupled material model for shape memory alloys (SMA) which includes the two main effects observed for these materials, pseudoelasticity and the shape memory effect. The constitutive equations are derived in the framework of large strains since the martensitic phase transformation involves inelastic deformations up to 10%, or even up to 20% if the plastic deformation after the phase transformation is taken into account. Therefore we apply a multiplicative split of the deformation gradient into elastic and inelastic parts, the latter concerning the martensitic phase transformation. An extended phase transformation function has been considered to include the tension‐compression asymmetry of textured SMA samples. In order to achieve a validation of the model by means of multiaxial experiments as well as to finally apply the concept in the simulation of complex structures, it is implemented into a finite element code. This implementation is based on an innovative integration scheme for the existing evolution equations and a monolithic solution algorithm for the coupled mechanical and thermal fields. The coupling effect is accurately investigated in several numerical examples including pseudoelasticity as well as the free and the suppressed shape memory effect. Finally, the model is used to simulate the pseudoelastic behaviour of an intracranial stent and the shape memory effect in a medical foot staple. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)