Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 11
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Book Description
The goal of this research was to understand the fundamental mechanics that drive the deformation and failure of shape memory alloys (SMAs). SMAs are difficult materials to characterize because of the complex phase transformations that give rise to their unique properties, including shape memory and superelasticity. These phase transformations occur across multiple length scales (one example being the martensite-austenite twinning that underlies macroscopic strain localization) and result in a large hysteresis. In order to optimize the use of this hysteretic behavior in energy storage and damping applications, we must first have a quantitative understanding of this transformation behavior. Prior results on shape memory alloys have been largely qualitative (i.e., mapping phase transformations through cracked oxide coatings or surface morphology). The PI developed and utilized new approaches to provide a quantitative, full-field characterization of phase transformation, conducting a comprehensive suite of experiments across multiple length scales and tying these results to theoretical and computational analysis. The research funded by this award utilized new combinations of scanning electron microscopy, diffraction, digital image correlation, and custom testing equipment and procedures to study phase transformation processes at a wide range of length scales, with a focus at small length scales with spatial resolution on the order of 1 nanometer. These experiments probe the basic connections between length scales during phase transformation. In addition to the insights gained on the fundamental mechanisms driving transformations in shape memory alloys, the unique experimental methodologies developed under this award are applicable to a wide range of solid-to-solid phase transformations and other strain localization mechanisms.
Author: Guozheng Kang
Publisher: Springer Nature
ISBN: 9819927528
Category : Technology & Engineering
Languages : en
Pages : 312
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Book Description
Written by leading experts in the field, this book highlights an authoritative and comprehensive introduction to thermo-mechanically coupled cyclic deformation and fatigue failure of shape memory alloys. The book deals with: (1) experimental observations on the cyclic deformation and fatigue failure in the macroscopic and microscopic scales; (2) molecular dynamics and phase-field simulations for the thermo-mechanical behaviors and underlying mechanisms during cyclic deformation; (3) macroscopic phenomenological and crystal plasticity-based cyclic constitutive models; and (4) fatigue failure models. This book is an important reference for students, practicing engineers and researchers who study shape memory alloys in the areas of mechanical, civil and aerospace engineering as well as materials science.
Author: Asheesh Lanba
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
This work aims to experimentally establish processing-structure-property relationships in wide-hysteresis NiTiNb shape memory alloys. Manufactures supplied custom composition cast materials and off-the-shelf deformation processed (i.e. small diameter rods and thin sheets) NiTiNb alloys, and thus different extents of processing are studied. Microstructure characterization of these materials highlights the impact of processing on micro-constituent morphology. Thermo-mechanical experiments are conducted in order to contrast the mechanical and shape memory properties. Micro-deformation measurements are employed to visualize strain localization associated with the differently processed microstructures. Mechanistic and phenomenological rationale are developed that correlate the micro-constituent morphology and its interaction with the underlying martensitic phase transformation to the mechanical and shape memory behavior.The cast and deformation-processed NiTiNb microstructures are characterized via electron and acoustic microscopy. The microstructures are also altered via annealing. The cast microstructure reveals that the addition of Nb as a ternary element in NiTi results in a microstructure with [beta] particles which are primarily Nb in a eutectic mixture with the [alpha] NiTi(Nb) phase. The eutectic mixture is cellular-like with areas of [alpha] NiTi(Nb) matrix material in between. The martensitic transformation, which is a reversible diffusionless crystallographic phase change that can be thermally- or stress-induced between a high temperature austenitic phase and low temperature martensitic phase, only takes place in this matrix. Two different deformation-processed alloys are studied; a rolled sheet and an extruded rod. Deformation-processing breaks up the eutectic structure resulting in a composite microstructure with discontinuous aligned second phase Nb-rich [beta]-particle reinforcements. Annealing causes the Nb-rich particles to grow, and also increases the inter-particle spacing in both cast and deformation processed alloys.The shape memory behavior, characterized via thermal cycling with and without an external stress, and the mechanical properties, characterized from isothermal deformation to failure at different temperatures, are contrasted for cast and deformation-processed microstructures. The stress-free thermal cycling allows us to establish the characteristic transformation temperatures along with the elastic and irreversible energies associated with the transformation. Thermal cycling under load is used to characterize the transformation temperatures, thermal hysteresis, and the recoverable and permanent deformations. The isothermal deformation is used to contrast the stress-induced transformation and subsequent plastic deformation using the critical transformation stress and strain, elastic moduli, yield stress, and strain at failure. The work finds the experimental evidence correlating strain energy relaxation and widening of hysteresis and reverse transformation temperature interval.This comparative study between the cast and deformation processed alloys is augmented by undertaking a multi-scale deformation analysis including digital image correlation to measure micro-scale strain localizations. The strain localizations are characterized in-situ, and allow the comparison of the impact of different micro-constituents on the evolution of localized deformations during the stress-induced transformation and shape memory recovery. Localized regions of high strain accompany the stress-induced transformation in cast alloys that lead to fracture, whereas the stress-induced transformation region in processed alloys has no such strain concentrations.The micro-constituent morphology in both the cast and deformation-processed alloys cause martensite stabilization, however the deformation processed microstructure promotes larger irreversibility and shows evidence of strain energy relaxation that is missing in cast alloys. The eutectic boundaries in the cast microstructure likely prohibit interaction of the martensitic transformation with the particles, and promote large strain localizations during the stress-induced transformation. Such boundaries are missing in the deformation-processed composite microstructure, and thus the particles interact more with the martensitic transformation that leads to the larger irreversibility, improved ductility and better mechanical properties.
Author: George A. Pantazopoulos
Publisher: MDPI
ISBN: 303928276X
Category : Technology & Engineering
Languages : en
Pages : 476
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Book Description
The era of lean production and excellence in manufacturing, advancing with sustainable development, demands the rational utilization of raw materials and energy resources, adopting cleaner and environmentally-friendly industrial processes. In view of the new industrial revolution, through digital transformation, the exploitation of smart and sophisticated materials systems, the need of minimizing scrap and increasing efficiency, reliability and lifetime and, on the other hand, the pursuit of fuel economy and limitation of carbon footprint, are necessary conditions for the imminent growth in a highly competitive economy. Failure analysis is an interdisciplinary scientific topic, reflecting the opinions and interpretations coming from a systematic evidence-gathering procedure, embracing various important sectors, imparting knowledge, and substantiating improvement practices. The deep understanding of material/component role (e.g., rotating shaft, extrusion die, gas pipeline) and properties will be of central importance for fitness for purpose in certain industrial processes and applications. Finally, it is hoped and strongly believed that the accumulation of additional knowledge in the field of failure mechanisms and the adoption of the principles, philosophy, and deep understanding of failure analysis process approach will strongly promote the learning concept, as a continuously evolving process leading to personal and social progress and prosperity.
Author: M. Fremond
Publisher: Springer
ISBN: 3709143489
Category : Technology & Engineering
Languages : en
Pages : 152
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Book Description
This book consists of two chapters. The first chapter deals with the thermomechanical macroscopic theory describing the transformation and deformation behavior of shape memory alloys. The second chapter deals with the extensive and fundamental review of the experimental works which include crystallography, transformations and mechanical characteristics in Ti-Ni, Cu-base and ferrous shape memory alloys.
Author: T W Duerig
Publisher: Butterworth-Heinemann
ISBN: 1483144755
Category : Technology & Engineering
Languages : en
Pages : 512
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Book Description
Engineering Aspects of Shape Memory Alloys provides an understanding of shape memory by defining terms, properties, and applications. It includes tutorials, overviews, and specific design examples—all written with the intention of minimizing the science and maximizing the engineering aspects. Although the individual chapters have been written by many different authors, each one of the best in their fields, the overall tone and intent of the book is not that of a proceedings, but that of a textbook. The book consists of five parts. Part I deals with the mechanism of shape memory and the alloys that exhibit the effect. It also defines many essential terms that will be used in later parts. Part II deals primarily with constrained recovery, but to some extent with free recovery. There is an introductory paper which defines terms and principles, then several specific examples of products based on constrained recovery. Both Parts III and IV deal with actuators. Part III introduces engineering principles while Part IV presents several of the specific examples. Finally, Part V deals with superelasticity, with an introductory paper and then several specific examples of product engineering.
Author: Inderjit Chopra
Publisher: Cambridge University Press
ISBN: 052186657X
Category : Science
Languages : en
Pages : 925
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Book Description
This book focuses on smart materials and structures, which are also referred to as intelligent, adaptive, active, sensory, and metamorphic. The ultimate goal is to develop biologically inspired multifunctional materials with the capability to adapt their structural characteristics, monitor their health condition, perform self-diagnosis and self-repair, morph their shape, and undergo significant controlled motion.
Author: Ashley N. Bucsek
Publisher:
ISBN:
Category : Deformations (Mechanics)
Languages : en
Pages : 156
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Book Description
Author: Antonio Concilio
Publisher: Elsevier
ISBN: 0080999212
Category : Technology & Engineering
Languages : en
Pages : 449
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Book Description
Shape Memory Alloy Engineering introduces materials, mechanical, and aerospace engineers to shape memory alloys (SMAs), providing a unique perspective that combines fundamental theory with new approaches to design and modeling of actual SMAs as compact and inexpensive actuators for use in aerospace and other applications. With this book readers will gain an understanding of the intrinsic properties of SMAs and their characteristic state diagrams, allowing them to design innovative compact actuation systems for applications from aerospace and aeronautics to ships, cars, and trucks. The book realistically discusses both the potential of these fascinating materials as well as their limitations in everyday life, and how to overcome some of those limitations in order to achieve proper design of useful SMA mechanisms. Discusses material characterization processes and results for a number of newer SMAs Incorporates numerical (FE) simulation and integration procedures into commercial codes (Msc/Nastran, Abaqus, and others) Provides detailed examples on design procedures and optimization of SMA-based actuation systems for real cases, from specs to verification lab tests on physical demonstrators One of the few SMA books to include design and set-up of demonstrator characterization tests and correlation with numerical models
Author: Jeff Perkins
Publisher: Springer Science & Business Media
ISBN: 1468422111
Category : Technology & Engineering
Languages : en
Pages : 577
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Book Description
The International Symposium on Shape Memory Effects and Appli cations was held at the University of Toronto on May 19-20, 1975, in four sessions over two days, as part of the regular 1975 Spring Meeting of The Metallurgical Society of AlME, sponsored by the Physical Metallurgy Committee of The Metallurgical Society. This was the first symposium on the subject, the only previous meeting at all related being the 1968 NOL Symposium on TiNi and Associated Compounds. One of the major intentions of this Symposium was to provide a forum for cross-communication between workers in the diverse metallurgical areas pertinent to shape memory effects, areas such as martensitic transformation, crystallography and thermodynamics, mechanical behavior, stress-induced transformation, lattice sta bility, and alloy development. Authors were encouraged to place an emphasis on delineation of general controlling factors and mech anisms, and on comparison of shape memory effect alloy systems with systems not exhibiting SME.
