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| Among the broad class of smart materials, {\itshape{shape-memory alloys}} (SMAs) have unique features due to their ability to regain the original shape either during unloading or through a thermal cycle. Thanks to such properties, SMAs are exploited in innovative applications.
A substantial research effort has been conducted
with the aim of developing reliable constitutive models to be used as design
tools for SMA devices. Among the others, macroscopic models appear to be a powerful
tool for SMA behavior simulation.
Accordingly, the present work aims to develop a more flexible and general 3D constitutive
model, along the lines of what recently proposed by Auricchio and Bonetti (2013).
The proposed model introduces volume proportions of different configurations of crystal lattice (i.e., austenite, single- and multiple-variant martensites) as scalar internal variables and the direction of single-variant martensite as tensorial one.
The theoretical framework allows for a completely independent description of phase transformations, leading to a very flexible frame in terms of model features and allowing to capture several physical phenomena, involving martensite reorientation, different kinetics between forward/reverse phase transformations, smooth thermo-mechanical response, low-stress phase transformations, as well as transformation-dependent elastic properties.
The model and its numerical implementation are tested on several boundary-value problems. |
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