Toughening in Shape Memory Alloy Reinforced Composites

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Material Information

Title:
Toughening in Shape Memory Alloy Reinforced Composites
Physical Description:
1 online resource (209 p.)
Language:
english
Creator:
Barrie, Fatmata
Publisher:
University of Florida
Place of Publication:
Gainesville, Fla.
Publication Date:

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Materials Science and Engineering
Committee Chair:
MYERS,MICHELE V
Committee Co-Chair:
SODANO,HENRY
Committee Members:
MECHOLSKY,JOHN J,JR
PATTERSON,BURTON ROE
VU,LOC QUOC

Subjects

Subjects / Keywords:
composite -- fracture -- martensite -- toughness
Materials Science and Engineering -- Dissertations, Academic -- UF
Genre:
Materials Science and Engineering thesis, Ph.D.
bibliography   ( marcgt )
theses   ( marcgt )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
born-digital   ( sobekcm )
Electronic Thesis or Dissertation

Notes

Abstract:
Materials capable of undergoing martensitic phase transformations have been shown to inherently increase the fracture toughness of monolithic and composite materials, in a process known as transformation toughening.  This toughening behavior via martensitic transformations has been extensively studied in transformation induced plasticity (TRIP) steels, stabilized zirconia, and some titanium alloy systems, however there is a limited amount of data on the effect of the martensitic phase transformation in composites reinforced with un-prestrained shape memory alloys (SMAs). Therefore, the objective of this work was to gain a fundamental understanding of how the constrained SMA martensitic phase transformation affects the fracture toughness of SMA reinforced composites. J-integral fracture toughness testing was performed on nickel titanium (NiTi) SMAs in both epoxy and metal matrices.  In addition to the SMAs, non-transforming aluminum and steel reinforcements were tested for comparative purposes.  Systematic single fiber pullout tests were also performed on epoxy composites embedded with NiTi SMA wires to determine the effect of the martensite phase transformation and variant reorientation processes on composite debonding since the interfacial behavior is known to affect composite fracture toughness.  The NiTi was heat-treated to produce varying stable room temperature phases, elastic moduli, and transformation stresses. This work found that SMA fibers that were deformed in the austenite phase had greater debond loads as compared to SMAs that were deformed in the martensite phase for the tested embedded fiber lengths for the tested embedded lengths.  Moreover, the SMA martensite transformation and variant reorientation did not appear to inherently increase the fracture toughness of a composite for the composite geometry and reinforcement orientation examined.  The driving factor of toughening in SMA fiber reinforced composites may be the mechanical properties, elastic modulus and yield stress.  The conclusions drawn were corroborated through analytical studies. In order to maximize the SMA contribution to fracture toughness, SMAs may likely need to be pre-strained prior to being embedded within a matrix.  Pre-straining results in compressive stresses on the matrix because the SMAs want to retract to recover its original shape.  In this sense the compressive mechanism within the pre-strained SMA and the stress-induced phase transformation in stabilized zirconia are similar.
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Statement of Responsibility:
by Fatmata Barrie.
Thesis:
Thesis (Ph.D.)--University of Florida, 2013.
Local:
Adviser: MYERS,MICHELE V.
Local:
Co-adviser: SODANO,HENRY.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2014-12-31

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Classification:
lcc - LD1780 2013
System ID:
UFE0045416:00001