Modeling of Shape Memory Alloys

169 Pages·2014·5.52 MB·English

Modeling of Shape Memory Alloys: Phase
Transformation/Plasticity Interaction at the Nano Scale and
the Statistics of Variation in Pseudoelastic Performance
Dissertation
Presented in Partial Fulfillment of the Requirements for the Degree
Doctor of Philosophy in the Graduate School of The Ohio State
University
By
Harshad Madhukar Paranjape, M.S.
Graduate Program in Materials Science and Engineering
The Ohio State University
2014
Dissertation Committee:
Professor Peter Anderson, Advisor
Professor Michael Mills
Professor Yunzhi Wang
(cid:13)c Copyright by
Harshad Madhukar Paranjape
2014
Abstract
Shapememoryalloys(SMA)showtworemarkableproperties-pseudoelasticityand
shape memory effect. These properties make them an attractive material for a vari-
ety of commercial applications. However, the mechanism of austenite to martensite
phase transformation, responsible for these properties also induces plastic deforma-
tion leading to structural and functional fatigue. Micron scale experiments suggest
that the plastic deformation is induced in part due to the local stress field of the
fine martensite microstructure. However, the results are qualitative and the nature
of transformation-plasticity interaction is dependent on factors like the width of the
interfaces.
This thesis presents a new modeling approach to study the interaction between
martensite correspondence variant scale microstructure and plastic deformation in
austenite. A phase field method based evolution law is developed for phase transfor-
mation and reorientation of martensite CVs. This is coupled with a crystal plasticity
law for austenite plastic deformation. The model is formulated with finite deforma-
tion and rotations. The effect of local crystal orientation is incorporated. An explicit
time integration scheme is developed and implemented in a finite element method
(FEM) based framework, allowing the modeling of complex boundary conditions and
arbitrary loading conditions.
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Two systematic studies are carried out with the model. First, the interaction
between plasticity and phase transformation is studied for load-free and load-biased
thermal cycling of single crystals. Key outcomes of this study are that, the residual
martensite formed during thermal cycling provides nucleation sites for the phase
transformation in the subsequent cycles. Further, the distribution of slip on different
slip systems is determined by the martensite texture. This is a strong evidence
for transformation induced plasticity. In the second study, experimentally informed
simulations of NiTi micropillar compression are performed. The results reveal that
the slip system activated, depends on the nature of the local deformation created by
martensiteCVsattheaustenite-martensiteinterface. Thisisinqualitativeagreement
with the past analytical and experimental work. There are other factors like the
width of the A-M interface, that influence the interaction between slip and phase
transformation.
Atthegranularlengthscale, asystematicstudyofthefactorsinfluencingstatistics
of the pseudoelastic performance of the grains in a polycrystal SMA is performed.
An existing grain scale microstructural FEM model calibrated to Ti-50.9at.%Ni is
used to achieve this. Local crystal orientation of the grain, crystal orientation of
the neighboring grains and the nature of the interfaces between the parent and the
neighbors are the factors responsible for introducing a variation in the grain perfor-
mance. A predictive function for the performance of a grain, as a function of the
Schmid factors for transformation for the parent and neighbors is proposed. Two
strategies are proposed to improve grain performance. The first is to reduce the num-
ber of interfaces, e.g. by constructing a bamboo or isostrain arrangement of grains.
The second is to employ high-symmetry interfaces between grains, so that multiple
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equivalent martensite plates can be activated at the interfaces, without compromising
performance.
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This dissertation is dedicated to my parents Smita and Madhukar Paranjape
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Acknowledgments
This thesis has been made possible by direct and indirect support from friends,
family members, colleagues, advisers and funding agencies. Here I would like to take
a moment to share my gratitude for them.
I would like to thank my adviser Prof. Peter Anderson for his constant encour-
agement, patience and advise about technical and non-technical aspects of my Ph.D.
Without him, this thesis would not have taken shape.
Prof. Michael Mills has provided feedback throughout the making of this thesis.
This has helped in anchoring my modeling based research to experimental results. I
would like to thank him for his help and being on my dissertation committee.
Prof. Yunzhi Wang has provided valuable feedback about the phase field method.
I owe my gratitude to him for this and for being on my dissertation committee.
I would like to thank Prof. Aaron Stebner at the Colorado School of Mines and
Dr. Ronald Noebe at NASA Glenn Research Center for their technical feedback.
Their advise has helped shape this work as well as resultant publications.
Dr. Sivom Manchiraju at ANSYS has provided immense help throughout my time
at The Ohio State University. I cannot thank him enough for his feedback about the
work and for his help with the formulation of the phase field model.
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My colleagues in the lab, Drs. Michael Gram, Lin Li, John Carpenter and Xiang
Chen, David Gutschick, Yanyi Xu, Danielle Dunham and Marc Doran provided a
stimulating and pleasant work environment. I would like to thank them all.
I would like to thank my friends in Columbus - Swanand Phadke, Neil Sawant,
Nisheet Singh, Manjunath Venugoapal-Reddy, Vivek Venkatachalam, Ashutosh Ku-
mar, Ashwini Chandra, Anupam Vivek, Sidharth Mohan, Harshad Pathak and Chai-
tanya Shivade for making my stay in Columbus enjoyable.
Finally I would like to thank my parents, Smita and Madhukar Paranjape for their
tremendous support, patience and love. Without their constant support, none of my
academic endeavors would have been possible.
FundingforthisresearchwasprovidedbytheNationalScienceFoundationthrough
the Metallic Nanostructures Program (GOALI DMR 1207494). Computational re-
sources at the Ohio Supercomputer Center were used under contract PAS0676. I
would like to acknowledge their support.
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Vita
1986 ........................................Born - Pune, India
2009 ........................................B.Tech. in Metallurgical Engineering
and Materials Science.
Indian Institute of Technology Bom-
bay, Mumbai, India
2012 ........................................M.S. in Materials Science and Engi-
neering.
The Ohio State University, Columbus,
OH, USA
2009-present ................................Graduate Research Associate,
The Ohio State University.
Publications
Research Publications
S. Raveendra, H. Paranjape, S. Mishra, H. Weiland, R. D. Doherty, and I. Sama-
jdar, “Relative Stability of Deformed Cube in Warm and Hot Deformed AA6022:
Possible Role of Strain-Induced Boundary Migration,” Metallurgical and Materials
Transactions A, vol. 40, pp. 2220 2230, 2009.
S. Raveendra, A. Kanjarla, H. Paranjape, S. Mishra, L. Delannay, I. Samajdar, and
P. Van Houtte, “Strain Mode Dependence of Deformation Texture Developments:
Microstructural Origin,” Metallurgical and Materials Transactions A, pp. 1 12, 2011.
G. C. Ebersole, H. Paranjape, P. M. Anderson, and H. M. Powell, “Influence of
hydration on fiber geometry in electrospun scaffolds,” Acta Biomaterialia, vol. 8, no.
12, pp. 4342 4348, Dec. 2012.
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Paranjape, Harshad, and Peter M. Anderson “Texture and Grain Neighborhood
Effects on NiTi Shape Memory Alloy Performance,” Modelling and Simulation in
Materials Science and Engineering, vol. 22, no. 7, October 2014.
Fields of Study
Major Field: Materials Science and Engineering
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