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Nanotechnology in Mechanical Engineering


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Title: Nanotechnology in Mechanical Engineering

Nanotechnology in Mechanical Engineering
Outline of the Presentation
  • Lecture
  • In-class group activities
  • Video Clips
  • Homework

Course Outline
  • Lecture - I
  • Introduction to Nano-
  • Technology in Engineering
  • Basic concepts
  • Length and time scales
  • Nano-structured materials
  • - Nanocomposites
  • - Nanotubes and nanowire
  • Applications and Examples
  • Lecture II
  • Nano-Mechanics
  • Nanoscale Thermal
  • and FlowPhenomena
  • Experimental
  • Techniques
  • Modeling and
  • Simulation

Lecture Topics
  • We will address some of the key issues of
    nano-technology in Mechanical Engineering.
  • Some of the topics that will be addressed are
    nano-structured materials nanoparticles and
    nanofluids, nanodevices and sensors, and

Major Topics in Mechanical Engineering
  • Mechanics
  • Statics Deals with forces, Moments,
    equilibrium of a stationary body
  • Dynamics Deals with body in motion -
    velocity, acceleration, torque, momentum,
    angular momentum.
  • Structure and properties of material (Including
  • Thermodynamics, power generation, alternate
    energy (power plants, solar, wind, geothermal,
  • Design of machines and
  • structures
  • Dynamics system, sensors
  • and controls
  • Robotics
  • Computer-Aided Design
  • (CAD/CAM)
  • Computational Fluid
  • Dynamics (CFD) and
  • Finite Element Method
  • Fabrication and
  • Manufacturing processes

Diesel Engine Simulation Model
Fuel Cell Design and Development
Flow in micro channel
No slip condition
Slip Conditions
Length Scales in Sciences and Mechanics
Quantum Mechanics Deals with atoms - Molecular
Mechanics Molecular Networks - Nanomechanics
Nano-Materials - Micromechanics Macro-mechanic
Continuum substance
Quantum and Molecular Mechanics
  • All substances are composed molecules or atoms in
    random motion.
  • For a system consisting of cube of 25-mm on each
    side and containing gas with atoms.
  • To specify the position of each molecule, we need
    to three co-ordinates and three component
  • So, in order to describe the behavior of this
    system form atomic view point, we need to deal
    with at least
  • equations.
  • This is quite a computational task even with the
    most powerful (massively parallel multiple
    processors) computer available today.
  • There are two approaches to handle this
    situations Microscopic or Macroscopic model

Microscopic Vs Macroscopic
  • Approach -1 Microscopic viewpoint based on
  • kinetic theory and statistical mechanics
  • On the basis of statistical considerations and
    probability theory, we deal with average values
    of all atoms or molecules and in connection with
    a model of the atom.
  • Approach II Macroscopic view point
  • Consider gross or average behavior of a number of
    molecules that can be handled based on the
    continuum assumption.
  • We mainly deal with time averaged influence of
    many molecules.
  • These macroscopic or average effects can be
    perceived by our senses and measured by
  • This leads to our treatment of substance as an
    infinitely divisible substance or continuum.

Breakdown of Continuum Model
  • To show the limit of continuum or macroscopic
    model, let us consider the concept of density
  • Density is defined as the mass
  • per unit volume and expressed as
  • Where is the smallest volume for which
    substance can be assumed as continuum.
  • Volume smaller than this will lead to the fact
    that mass is not uniformly distributed, but
    rather concentrated in particles as molecules,
    atoms, electrons etc.
  • Figure shows such variation in density as volume
    decreases below the continuum limit.

Macroscopic Properties and Measurement
  • Pressure
  • Pressure is defined as the
  • average normal-component
  • of force per unit area and
  • expressed as
  • Where is the smallest volume for
    which substance can be assumed as continuum.

Pressure Measurement
For a pressure gauge, it is the average force
(rate of change of momentum) exerted by the
randomly moving atoms or molecules over the
sensors area.
Unit Pascal (Pa) or
Introduction- Nanotechnology
  • Nanoscale uses nanometer as the basic unit of
    measurement and it represents a billionth of a
    meter or one billionth of a part.
  • Nanotechnology deals with nanosized particles and
  • One- nm is about 3 to 5 atoms wide. This is very
    tiny when compared normal sizes encounter
  • - For example this is 1/1000th the width of
  • hair.

  • Any physical substance or device with structural
    dimensions below 100 nm is called nanomaterial or
  • Nanotechnology rests on the technology that
    involves fabrication of material, devices and
    systems through direct control of matter at
    nanometer length scale or less than 100 nm.

  • Nanoparticles can be defined as building blocks
    of nanomaterials and nanotechnology.
  • Nanoparticles include nanotubes, nanofibers,
    fullerenes, dendrimers, nanowires and may be
    made of ceramics, metal, nonmetal, metal oxide,
    organic or inorganic.
  • At this small scale level, the physical, chemical
    and biological properties of materials differ
    significantly from the fundamental properties at
    bulk level.
  • Many forces or effects such inter-molecular
    forces, surface tension, electromagnetic,
    electrostatic, capillary becomes significantly
    more dominant than gravity.
  • Nanomaterial can be physically and chemically
    manipulated to alter the properties, and these
    properties can be measured using nanoscale
    sensors and gages.

  • A structure of the size of an atom represents one
    of the fundamental limit.
  • Fabricating or making anything smaller require
    manipulation in atomic or molecular level and
    that is like changing one chemical form to other.
  • Scientist and engineers have just started
    developing new techniques for making

The nanoscience is matured. The age of
nanofabrication is here. The age of
nanotechnology - that is the practical use of
nanostructure has just started.
Nanotechnology in Mechanical Engineering
New Basic Concepts
Nano-Scale Heat Transfer
  • Structural materials
  • Nano devices and sensors
  • Coolants and heat spreaders
  • Lubrication
  • Engine emission reduction
  • Fuel cell nanoporous electrode/membranes/nanocat
  • Hydrogen storage medium
  • Sustainable energy generation - Photovoltaic
    cells for power conversion
  • Biological systems and biomedicine

Basic Concepts
  • Energy Carriers
  • Phonon Quantized lattice vibration energy
    with wave nature of propagation
  • - dominant in crystalline material
  • Free Electrons
  • - dominant in metals
  • Photon Quantized electromagnetic energy with
    wave nature of propagation
  • - energy carrier of radiative energy

Length Scales
  • Two regimes
  • I. Classical microscale size-effect domain
    Useful for microscale heat transfer in
    micron-size environment.

mean free path length of the substance
characteristic device dimension
II. Quantum nanoscale size-effect domain
More relevant to nanoscale heat transfer
characteristic wave length of the
or phonons
  • This length scale will provide the guidelines for
    analysis method- both theoretical and
    experimental methods
  • classical microscale domain or nanoscale
    size-effect domain.

Flow in Nano-channels
  • The Navier Stokes (N-S) equation of continuum
    model fails when the gradients of macroscopic
    variables become so steep that the length scale
    is of the order of average distance traveled by
    the molecules between collision.
  • Knudsen number ( ) is typical parameter
    used to classify the length scale and flow

Kn lt 0.01 Continuum approach with traditional
Navier-Stokes and no-slip boundary conditions
are valid. 0.01ltKnlt0.1 Slip flow regime and
N-S with slip boundary conditions are
applicable 0.1ltKnlt10 Transition regime
Continuum approach completely breaks
Molecular Dynamic Simulation Kn gt 10 Free
molecular regime The collision less Boltzman
equation is applicable.
Time Scales
  • Relaxation time for different collision process
  • Relaxation time for phonon-electron
  • interaction
  • Relaxation time for electron-electron
  • interaction
  • Relaxation time for phonon-phonon
  • interaction

Nanotechnology Modeling Methods
  • Quantum Mechanics
  • Atomistic simulation
  • Molecular Mechanics/Dynamics
  • Nanomechanics
  • Nanoheat transfer and Nanofluidics

Models for Inter-molecules Force
  • - Inter-molecular Potential
  • Model
  • - Inverse Power Law Model or
  • Point Centre of Repulsion
  • Model
  • - Hard Sphere Model
  • - Maxwell Model
  • - Lennard-Jones Potential
  • Model
  • Inter-molecular Potential Model

  • Nanotools are required for manipulation of matter
    at nanoscale or atomic level.
  • Certain devices which manipulate matter at atomic
    or molecular level are Scanning-probe
    microscopes, atomic force microscopes, atomic
    layer deposition devices and nanolithography
  • Nanolithography means creation of nanoscale
    structure by etching or printing.
  • Nanotools comprises of fabrication techniques,
    analysis and metrology instruments, software for
    nanotechnology research and development.
  • Softwares are utilized in nanolithography, 3-D
    printing, nanofluidics and chemical vapor

Nanoparticles and Nanomaterials
  • Nanoparticles
  • Nanoparticles are significantly larger than
    individual atoms and molecules.
  • Nanoparticles are not completely governed by
    either quantum chemistry or by laws of classical
  • Nanoparticles have high surface area per unit
  • When material size is reduced the number of atoms
    on the surface increases than number of atoms in
    the material itself. This surface structure
    dominates the properties related to it.
  • Nanoparticles are made from chemically stable
    metals, metal oxides and carbon in different

Carbon -Nanotubes
  • Carbon nanotubes are hollow cylinders made up of
    carbon atoms.
  • The diameter of carbon nanotube is few nanometers
    and they can be several millimeters in length.
  • Carbon nanotubes looks like rolled tubes of
    graphite and their walls are like hexagonal
    carbon rings and are formed in large bundles.
  • Have high surface area per unit volume
  • Carbon nanotubes are 100 times stronger than
    steel at one-sixth of the weight.
  • Carbon nanotubes have the ability to sustain high
    temperature 2000 C.

  • There are four types of carbon
  • nanotube Single Walled Carbon
  • Nanotube (SWNT), Multi Walled
  • Xarbon nanotube (MWNT), Fullerene
  • and Torus.
  • SWNTs are made up of single
  • cylindrical grapheme layer
  • MWNTs is made up of multiple
  • Grapheme layers.
  • SWNT possess important electric
  • properties which MWNT does not.
  • SWNT are excellent conductors, so finds its
    application in miniaturizing electronics

  • Formed by combining two or more nanomaterials to
    achieve better properties.
  • Gives the best properties of each individual
  • Show increase in strength, modulus of elasticity
    and strain in failure.
  • Interfacial characteristics, shape, structure and
    properties of individual nanomaterials decide the
  • Find use in high performance, lightweight, energy
    savings and environmental protection applications
  • - buildings and structures, automobiles
  • and aircrafts.

  • Examples of nanocomposites include nanowires
  • and metal matrix composites.
  • Classified into multilayered structures and
    inorganic or
  • organic composites.
  • Multilayered structures are formed from
    self-assembly of
  • monolayers.
  • Nanocomposites may provide heterostructures
    formed from
  • various inorganic or organic layers, leading
    to multifunctional
  • materials.
  • Nanowires are made up of various materials and
    find its
  • application in microelectronics for
    semiconductor devices.

Nanostructured Materials
  • All the properties of nanostructured are
    controlled by changes in atomic structure, in
    length scales, in sizes and in alloying
  • Nanostructured materials are formed by
    controlling grain sizes and creating increased
    surface area per unit volume.
  • Decrease in grain size causes increase in
    volumetric fraction of grain boundaries, which
    leads to changes in fundamental properties of

Different behavior of atoms at surface has been
observed than atom at interior. Structural and
compositional differences between bulk material
and nanomaterial cause change in properties.
  • The size affected properties are color, thermal
  • mechanical, electrical, magnetic etc.
  • Nanophase metals show increase in hardness and
  • of elasticity than bulk metals.
  • Nanostructured materials are produced in the
    form of
  • powders, thin films and in coatings.
  • Synthesis of nanostructured materials take place
    by Top
  • Down or Bottom- Up method.
  • - In Top-Down method the bulk solid is
    decomposed into
  • nanostructure.
  • - In Bottom-Up method atoms or molecules
  • assembled into bulk solid.
  • The future of nanostructured materials deal with
  • characteristics, processing into and from
    bulk material and
  • in new manufacturing technologies.

  • Nanofluids are engineered colloid formed with
    stable suspemsions of solid nano-particles in
    traditional base liquids.
  • Base fluids Water, organic fluids, Glycol, oil,
    lubricants and other fluids
  • Nanoparticle materials
  • - Metal Oxides
  • - Stable metals Au, cu
  • - Carbon carbon nanotubes (SWNTs,
  • diamond, graphite, fullerene,
    Amorphous Carbon
  • - Polymers Teflon
  • Nanoparticle size 1-100 nm

Nanofluid Heat Transfer Enhancement
  • Thermal conductivity enhancement
  • - Reported breakthrough in substantially
    increase ( 20-30) in thermal conductivity of
    fluid by adding very small amounts (3-4) of
    suspended metallic or metallic oxides or
  • Increased convective heat transfer
    characteristic for heat transfer fluids as
    coolant or heating fluid.
  • -

Nanofluids and Nanofludics
  • Nanofluids have been investigated
  • - to identify the specific transport
  • - to identify critical parameters
  • - to characterize flow characteristics in
  • micro and nano-channels
  • - to quantify heat exchange performance,
  • - to develop specific production,
  • and safety issues, and measurement and
  • simulation techniques

Nano-fluid Applications
  • Energy conversion and energy storage system
  • Electronics cooling techniques
  • Thermal management of fuel cell energy systems
  • Nuclear reactor coolants
  • Combustion engine coolants
  • Super conducting magnets
  • Biological systems and biomedicine

  • When the tools and processes of nanotechnology
    are applied towards biosystems, it is called
  • Due to characteristic length scale and unique
  • nanomaterials can find its application in
  • Nanocomposite materials can play great role in
    development of materials for biocompatible
  • Nano sensors and nanofluidcs have started
    playing an important role in diagnostic tests and
    drug delivering system for decease control.
  • The long term aim of nano-biotechnology is to
    build tiny devices with biological tools
    incorporated into it diagonistic and treatment..

National Nanotechnology Initiative in Medicine
  • Improved imaging (See
  • Treatment of Disease
  • Superior Implant
  • Drug delivery system and treatment using
    Denrimers, Nanoshells, Micro- and Nanofluidics
    and Plasmonics

- In order to improve the durability and
bio-compatibility, the implant surfaces are
modified with nano-thin film coating (Carbon
nano-particles). - An artificial knee joint or
hip coated with nanoparticles bonds to the
adjacent bones more tightly.
  • Nano-particles delivers treatment to targeted
    area or targeted tumors
  • - Release drugs or release radiation to heat up
    and destroy tumors or cancer cells

Self Powered Nanodevices and Nanogenerators
  • Nanosize devices or machined need nano-size power
    generator call nanogenerators without the need of
    a battery.
  • Power requirements of nanodevices or nanosystems
    are generally very small
  • in the range of nanowatts to microwatts.
  • Example Power source for a biosensor
  • - Such devices may allow us to develop
    implantable biosensors that can continuously
    monitor humans blood sugar level

  • Waste energy in the form of vibrations or even
    the human pulse could power tiny devices.
  • Arrays of piezoelectric could capture and
    transmit that waste energy to nanodevices
  • There are many power sources in a human body
  • - Mechanical energy, Heat energy,
    Vibration energy,
  • Chemical energy
  • A small fraction of this energy can be converted
    into electricity to power nano-bio devices.
  • Nanogenerators can also be used for other
  • - Autonomous strain sensors for structures
    such as bridges
  • - Environmental sensors for detecting
  • - Energy sensors for nano-robotics
  • - Microelectromecanical systems (MEMS) or
  • nanoelectromechanical system (NEMS)
  • - A pacemakers battery could be
    charged without
  • requiring any replacement

Nano-sensor and Nano-generator
Example Piezoelectric Nanogenerator
  • Piezoelectric Effect
  • Some crystalline materials generates
    electrical voltage when mechanically stressed
  • A Typical Vibration-based Piezoelectric
  • - Uses a two-layered beam with one end fixed
  • and other end mounted with a mass
  • - Under the action of the gravity the beam is
    bent with
  • upper-layer subjected to tension and
  • subjected to tension.

Conversion of Mechanical Energy to Electricityin
a Nanosystem

Gravity do not play any role for motion in
nanoscale. Nanowire is flexed by moving a ridged
from side to side.
Array of nanowires (Zinc Oxide) with
piezoelectric and semiconductor properties
Rectangular electrode with ridged
underside. Moves side to side in response to
external motion of the structure
Example Thermo Electric Nano-generator
  • Thermoelectric generator relies on the Seebeck
    Effect where an electric potential exists at the
    junction of two dissimilar metals that are at
    different temperatures.
  • The potential difference or the voltage produced
    is proportional to the temperature difference.
  • - Already used in Seiko Thermic Wrist

Bio-Nano Generators
  • Questions
  • 1. How much and what different kind of
  • does body produce?
  • 2. How this energy source can be utilized
  • produce power.
  • 3. What are the technological challenges?
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