The document discusses various types of smart materials and composites. It describes piezoelectric, electrostrictive, and magnetostrictive materials that change their properties in response to stimuli like deformation, electric fields, and magnetic fields. It also discusses shape memory alloys, chromic materials, and liquid crystals that change properties based on temperature, light, or electric charge. Advanced composites like polymer matrix composites, metal matrix composites, and ceramic matrix composites are described as having a matrix reinforced with fibers, particles, or another phase to improve properties.

1. DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY, ROORKEE
Smart materials
Type of Smart Material Input Output
Piezoelectric Deformation Potential difference
Electrostrictive Potential Difference Deformation
Magnetostrictive Magnetic Field Deformation
Thermoelectric Temperature Potential Difference
Shape Memory Alloys Temperature Deformation
Chromic Materials Light/Heat/Electricity Colour change
Photochromic Radiation Colour Change
Thermochromics Temperature Colour Change
Non-Newtonian Fluids Shear Viscosity
Photomechanical Radiation Deformation
Dielectric Elastomers Electric Field Large strains
Material that changes one or more of its properties in response to a stimulus.
Advance Composite Materials
Two distinct phases/interfaces separation  Reinforcement +
Matrix
Polymer Matrix Composite (PMC)
Typical reinforcements: glass, boron, carbon, aramids
Properties: high specific strength, specific stiffness
Applications: aerospace, sporting goods
Metal Matrix Composite (MMC)
Typical reinforcements: ceramic, metal, carbon
Properties: high operating T, abrasion resistant
Applications: aerospace, Sports equipment
Ceramic Matrix Composite (CMC)
Typical reinforcements: Ceramic
Properties: toughness, high T operation
Applications: aerospace, cutting tools

2. DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY, ROORKEE
Liquid Crystals
Definition: Fluids like liquids, anisotropic like solids
Semiconductors
A class of solids demonstrating electrical conductivities
between conductors and insulators
• Small bandgap gives conductivity at higher T
• Doping with impurities increases conductivity
Diode – A p-n junction allows current flow in only
one direction
Transistor- Consists of three layers of doped
material (npn or pnp)
LED - Diodes which are capable of photoemission;
radiated colour is dependent on material
Applications:
Consumer electronics, Laser Diodes, Integrated
Circuits
Applications
• Liquid Absorbance control: Smart windows
• Liquid Crystal Display (LCD)
• Liquid Crystal Thermometers
• Optical Imaging
Liquid
Crystal
Phases
Liquid Crystal Polymers
• Highly Crystalline Polymers
• Temperature and Chemical Resistance
• Nomex
• Kevlar

3. DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY, ROORKEE
Polymer Nanocomposites
Nano-scale Filler particles in a polymer matrix
Filler properties without losing bulk properties
What are they?
• Viscosity increases with rate of shear
• Hand particles (colloids) suspended in liquids
• Non-Newtonian fluids
How do they work?
• With energy of sudden impact hydrodynamics forces to
overcome repulsive forces between particles
• Particles stick together (hydrocluters)
• Fluid becomes rigid
Common Examples
• Corn starch and water
• Sand and water
Property Enhancement:
• Hardness
• Young’s modulus
• Durability
• Gas permeability
Applications:
• Timing belts
• Step assist
• Dual core tennis balls
• Car bumpers
Common Additives:
• Nanotubes
• Graphite
• Pristine clay
Dilatant Fluids
Applications:
• Body armour
• Traction control

4. DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY, ROORKEE
Stealth Materials Biomimetic Materials
Infrared: Embedding Engines, Baffles
Visual: “Air superiority blue-grey” paint
Acoustic: Mufflers
Radar: Deflect, Cancel or Absorb
Types of RADAR Absorbent Materials (RAM):
Iron Ball Paint Transforms waves into heat, absorbs
Salisbury screen Reflects waves out of phase , cancel
Material choice for Airframe
Aluminium: Strong, Light,
Reflective, Conventional
Carbon Fiber Comp.: Stronger,
Lighter(sonic), Reflective, Lower
CTE (Molding)
• Application of biological methods and systems in nature to the
study and design of engineering system
• Enhance today’s materials with technology inspired by biology
• Synthetic super hydrophobic surfaces
inspired by lotus leaf
• Self cleaning and water repelling
properties accomplished by silica
nanospheres instead of waxy
• Stimuli responsive polymer
nanocomposites inspires by sea
cucumbers
• Modulus reversibly increased or
decreased in response to
chemical regulators
• Synthetic Water proof adhesive bandage
inspired by Gecko’s foot
• Intermolecular vanderwaals forces allow
adhesion of biocompable, biodegradable,
elastic material that leaves no residue
• Adhesion directional and repeatable

5. DEPARTMENT OF METALLURGICAL AND MATERIALS ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY, ROORKEE
Metal Foams Thermoplastic Elastomers
• These are cellular structure made up of a solid metal containing a large
volume fraction of gas-filled pores.
• Closed-cell foam/sealed pores are referred to as metal forms
• Open-cell foam/interconnected network are referred as porous metal
Thermoplastics can be melted
and reshaped
• Not elastomeric
• Recyclable
Metals that can be used : Al, Ti, Ta
Properties
• Ultralight material (75-95% of the volume consists of void space)
• High compression strengths combined with good energy absorption
characteristics
• Very high porosity
• Thermal conductivity is low
• High strength
Applications of Closed-cell foam
• Structural application
• Impact absorbing in vehicles
• Load bearing structure with low
weight
Applications of open-cell foam
• Vibration and sound absorption
• Filtration and catalysis at high
temperatures
• Heat exchanger
• Medical devices
Elastomers are not thermoplastics
(cannot be melted and reshaped)
• Elastomeric Matrix is held
together by chemical bonds
(vulcanization), which cannot
be broken under high T
• Not recyclable
Thermoplastic Elastomers (TPE)
• Thermoplastic/elastomer hybrid
• Can be melted and reshaped
• Tough, formable, and chemically resistant
• Two main classification
• ionomers
• block copolymers
Applications
• High toughness athletic equipment's
• Cable jacketing
• Seal/ gaskets
• Tail light housing
E.g.: styrene-butadiene-styrene block copolymer
TPEs are cross-linked with physical bonds
• Can be broken under high T
• Therefore TPEs can be melted and reshaped