Physics of Multifunctional Materials

Concepts, Materials, Applications

Martin Gurka, Dr. rer. nat., Institute for Composite Materials, Kaiserslautern, Germany

978-1-60595-260-4, April 2018, 184 pages, 6×9, HC book

• Applies foundational physics and materials science concepts to piezoceramics, shape memory alloys, and switchable fluids
• Uses basic scientific measurements to address manufacturing, processing, and modeling
• Provides guidance on evaluating multifunctional materials
• Includes information on multifunctional materials’ applications for actuators and sensors


This book uses basic mechanical, thermodynamic, material science, and electrical concepts from well-known physics to explain the properties and performance of multifunctional materials. With familiar theory and a focus on phase transitions, the text offers a simple, elegant introduction to the design and operation of devices that incorporate piezoceramics, shape memory alloys, electrorheological and magnetorheological fluids. The physics equations and graphical data in this volume form a novel approach to characterizing and assessing smart materials.


From the author’s preface:

“The scope of this book is to explain the physics and materials science underlying multifunctional materials and composites made thereof. The text identifies and elaborates the fundamental principles of ferroelectricity, elastic phase transformation, and energy transfer mechanisms that form the common basis for understanding the functionality, application potential, and limitations of a smart materials system.

“While these principles are independent of specific kinds of materials or particular applications, they are explained in the context of a representative material and application. That is, the principles apply to whole groups of materials and can be used to differentiate between them. The present book endeavors to cover the basic physics pertaining to multifunctional materials: from mechanics, electrodynamics, thermodynamics, and condensed matter physics, either as a short summary or as applied to selected examples from the large group of multifunctional materials. Familiar physics principles are thus used as a guide to the nature and design of these materials.

“The book concentrates on three different types of multifunctional materials: piezoceramics, shape-memory alloys, and switchable fluids (electrorheological and magnetorheological fluids). These materials are the best-known commercially available multifunctional materials with the most applications. More interesting in the context of this book is the fact that although the aforementioned examples are all made from very different materials, namely, ceramics, metals, and fluids, respectively, their multifunctionality is based on the same underlying principle — a structural phase transition induced by an external field, either an electrical, magnetic, or thermal field. This is one reason why multifunctional polymeric materials are not discussed. In most cases, polymer multifunctionality relies on mechanisms besides phase transition.”

Preface

Chapter 1. Introduction

Chapter 2. Multifunctional Materials or Smart Materials versus Normal Materials
2.1. General Definition of Multifunctional Materials from a Physical Aspect
2.1.1. Passive Multifunctional Materials
2.1.2. Active Multifunctional Materials
2.1.3. Smart and Very Smart Materials
2.2. Multifunctional Materials in Complex Systems or Applications
2.3. Economic Aspects of Multifunctional Materials

Chapter 3. Basic Physics and Materials Science
3.1. Basic Mechanics
3.1.1. Force
3.1.2. Work
3.1.3. Energy
3.1.4. Power
3.2. Elasticity, Stiffness and Strength
3.2.1. Plastic Deformation
3.3. Oscillations
3.3.1. The Influence of Damping
3.3.2. Different Forms of Energy
3.3.3. Forced Oscillations
3.3.4. Impedance Matching and Work Performed by an Oscillating Object
3.4. Diffusion and Heat Transfer
3.4.1. Steady State Heat Conduction
3.4.2. Transient Temperature Gradient
3.4.3. Thermal Relaxation Time
3.4.4. Diffusion
3.5. Phase Transitions

Chapter 4. Classification of Multifunctional Materials
4.1. Performance Index of a Multifunctional Material
4.2. Single Stroke Performance
4.3. Performance at Cyclic Operation
4.4. Performance Data of Various Materials

Chapter 5. Ferroelectrics—Piezoelectric Materials
5.1. Perovskite Structure and Spontaneous Polarization
5.2. Ferroelectric Hysteresis
5.3. Piezoelectric Tensor
5.4. Dielectric Permittivity, Elastic Constant
5.5. Sensor- and Actuator-Equation
5.6. Electrostriction
5.7. Dynamic Behavior of Piezoelectric Elements
5.8. Coupling Factors and Efficiency
5.9. Frequency Coefficient
5.10. Pyroelectric Behavior
5.11. Compensation of the Temperature Dependency
5.12. Nonlinear Behavior of Ferroelectric Materials
5.13. Piezoelectric Materials
5.13.1. Piezoelectric Crystals
5.13.2. Piezoelectric Ceramics
5.13.3. Piezoelectric Polymers
5.13.4. Piezoelectric Composite Materials

Chapter 6. Shape Memory Alloys
6.1. Structural Thermo-elastic Phase Transition in Shape Memory Alloys
6.2. Dependency Between Microstructure and Elastic Behavior of SMA
6.3. Discontinuous Change of Physical Properties—Martensitic Phase Transition
6.4. Shape Memory Alloys and Entropy
6.5. Different Approaches to Describe the Shape-Memory Effect
6.5.1. Phenomenological Description of the Shape-Memory Effects
6.5.2. Kinematic Description of a SMA Device
6.5.3. Physically Based Motivated Microscopic Material Model for SMA
6.6. Quantitative Models for Shape Memory Alloys
6.7. Thermal Properties of SMA Actuators
6.8. Materials and Important Properties

Chapter 7. Magnetorheological and Electrorheological Fluids
7.1. Viscoelastic Properties and Basic Rheology
7.1.1. Newtonian Fluids and Viscosity
7.1.2. Viscoelasticity
7.1.3. Thixotropic and Rheopectic Fluids
7.2. Some Rheological Models
7.2.1. Flow-curve Model According to Bingham
7.2.2. Flow-curve Model According to Herschel/Bulkley
7.2.3. Flow-curve Model According to Casson
7.3. Understanding the Microscopic Structure of ERF and MRF
7.4. ER- and MR-effect Explained by the Interaction of Induced Dipoles
7.4.1. Ferromagnetic Polarization
7.4.2. Dielectric Polarization
7.5. Applications—Switchable Fluid Acting as a Valve
7.5.1. Shear-mode Operation of a Switchable Fluid
7.5.2. Flow-mode Operation of a Switchable Fluid
7.5.3. Minimum Required Fluid Volume for a Given Application
7.5.4. Dynamic Response
7.5.5. Geometric Considerations
7.5.6. Energy Density in a Switchable Fluid
7.5.7. Response Time
7.5.8. Sedimentation and Re-dispersing
7.6. Selected Properties of Switchable Fluids

Chapter 8. Applications—Multifunctional Materials as Actuators and Sensors
8.1. General Considerations
8.2. SMA Wire-actuators for Active Hybrid Composites
8.2.1. Combination of SMA and Fiber-reinforced Polymers
8.2.2. Load Transfer Between SMA and Composite Materials
8.2.3. Qualitative Description of an SMA Bimorph
8.2.4. Example of a First Application: Active Vortex Generators for an Airplane
8.3. Piezo Electric Elements (PXE) as Actuators and Sensors
8.3.1. Quasistatic versus Resonant Operation of a PX Element
8.3.2. Axial and Transversal Piezo Actuators—Quasistatic Actuation
8.3.3. Axial and Transversal Transducers as Sensors for Quasistatic Operation
8.3.4. Transversal Transducers Used as Bending Elements
8.3.5. Operation in Resonance Mode—Acoustic Transducers

References
Index

  1. :

    The book is intended as an introduction to the physics of multi-functional materials and focuses mainly on piezoceramics, shape-memory alloys and electro-magneto-rheological (switchable) fluids, which are commercially available materials with the most practical applications. It should be noted that the multi-functionality of these materials is based on a structural phase transition induced by an external electric, magnetic or thermal field. Polymeric materials are briefly mentioned since their functionality mainly relies on fillers (electric or magnetic) or to the structure of the assembly of a specific device, like the Maxwell stress induced by attracting electrodes, which leads to the actuation of an electro-active polymer device. The general definition and categories of multifunctional materials and their differences from traditional ones appear in chapter two, followed by basic physics and some materials science in chapter 3, with more detailed materials classification in chapter 4. Chapters 5 to 7 present the principles behind functionality of piezoceramics, shape-memory alloys and switchable fluids, ending the book with few case studies related to multi-functional materials as actuators and sensors. The author is trying to explain how the multifunctional material can be the enabling element of an active suspension or a vibration absorbing system in a vehicle and briefly what is the economic aspect in that commercial application.

    Overall, the textbook is well written, relatively easy to follow, with clearly drawn and presented diagrams and schematics that assist the reader to better understand the mathematical and technical concepts discussed. The author, Dr Martin Gurka, of the Institute for Composite Materials, Kaiserslautern, Germany, is a physicist who earned his PhD in nonlinear laser spectroscopy at the University of Heidelberg. He has extensive industrial experience in the field of multifunctional materials and developed production processes and applications for active composites.

    I won’t hesitate to recommend the book to our University library for the benefit of my final year engineering undergraduates and those research students who have an interest on multifunctional material systems. A useful practical guide also to practicing engineers who’d like to refresh their knowledge or improve their understanding of this important class of smart materials.

    –Professor C Soutis PhD (Cantab), CEng, FREng
    Head of the Aerospace Research Institute
    University of Manchester, UK

978-1-60595-260-4, April 2018, 184 pages, 6×9, HC book

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