# Comparative Study of Two Multiscale Thermomechanical Models of Polycrystalline Shape Memory alloys: Application to a Representative volume Element of Titanium-Niobium

## TL;DR

This study compares two multiscale thermomechanical models for shape memory alloys, analyzing their differences and similarities through numerical simulations of titanium-niobium SMA, aiming to improve modeling tools for multiaxial loadings.

## Contribution

It provides the first comparative analysis of crystal plasticity and microstructure evolution models for SMA, advancing understanding and development of efficient simulation tools.

## Key findings

- Both models successfully simulate stress-strain behavior.
- Differences in microstructure evolution predictions are highlighted.
- Model comparisons align with experimental data for <100>, <110>, <111> directions.

## Abstract

This paper presents a comparative study between two micro-macro modeling approaches to simulate stress-induced martensitic transformation in shape memory alloys (SMA). One model is a crystal plasticity based model and the other describes the evolution of the microstructure with a Boltzmann-type statistical approach. Both models consider a self-consistent scheme to perform the scale transition from the local thermomechanical behavior to the global one. The way the two modeling approaches describe the local behavior is analyzed. Similarities and differences are pointed out. Numerical simulations of the thermo-mechanical behavior of an isotropic titanium-niobium SMA are performed. These alloys have known a growing interest of scientific community given their high potential for application in the biomedical field. Stress-strain curves obtained from the two simulations are compared with experimental results. Evolutions of volume fractions of martensite variants predicted by the two approaches are compared for <100>, <110> and <111> tensile directions. Due to the absence of comparative studies between multiscale models dedicated for SMA, this paper fills a gap in the state of the art in this field and provides a significant step toward the definition of an efficient numerical tool for the analysis of SMA behavior under multiaxial loadings.

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Source: https://tomesphere.com/paper/1906.07915