Smart Materials for Sensing and Actuation

Bishakh Bhattacharya

Department of Mechanical Engineering

Indian Institute of Technology Kanpur

Cover Photo Courtesy:Dr. Manuel Ochoa, Purdue University:

Organization

• Application of Smart Material• Smart systems using Smart

Materials • Smart Actuators• Direct and Reverse Effects• Shape Memory Effect• Self Healing

Five Major Applications

• Vibration and Chatter Control• Shape Control • Micro-Positioning Devices• Distributed Sensing• Energy Harvesting for

Wireless Sensor Networks

Active Vibration ControlThe liquid contained in the dampers has magneto-rheological properties. Tiny magnetic particles are bound inside the basic oil which is used to fill the dampers.

When a magnetic field is applied, the magnetic particles are aligned against the direction of movement of the damper. This allows the firmness of the dampers to be increased or decreased within a fraction of a second.

Active Shape Control

Laser-MicromachinedMagnetically-Functionalized Hygroscopic Bilayer: A Low-Cost Smart Material

Micro-Positioning DevicesA P-545 PInano® XY & XYZ Piezo Stages for Microscope Slides

Sub-nanometer resolution

200 µm Travel Ranges

Extremely Fast Step & Settle, From 5 msec

Energy Harvesting SensorsA typical thermoelectric (TE) energy harvesting system of five key components—TE generator, heatsink, voltage regulation, charge management and energy storage, and power/load management

Output

Input

Current/Charge Magnetization Strain Temperature Light

Electric

Field

Conductivity

Permittivity

Electromagnetic

Effect

Reverse

Piezoelectric

Effect

SA

Ohmic

Resistance

Electro-Optic

effect

Magnetic

Field

Eddy Current Effect

Permeability

Joule Effect

Magnetostriction

SA

Magneto-caloric

Effect

Magneto-Optic

effect

Stress Direct Piezoelectric

Effect

SS

Villary Effect

SS

Elastic Modulus

Thermo-

Mechanical

Effect SS

Photo-elastic

Effect

SS

Heat Pyroelectric Effect Thermo-

magnetization

Thermal

Expansion/Phase

Transition

SA

Specific Heat

Thermo-

luminescence

Light Photo-voltaic Effect Photo-

magnetization

Photostriction

SA

Photo-thermal

effect

Refractive

Index

Smart Actuators

Input Parameter Actuator Type/ Devices

Electric Field Piezoelectric/Electrostrictive Electrostatic (MEMS)Electro- Rheological Fluid

Magnetic Field MagnetostrictiveMagneto-Rheological Fluid

Chemical Mechano-chemicalHeat Shape Memory Alloy

Shape Memory Polymer

Light Photostrictive

Properties

important

for

Actuation

Piezoelectric Material Magnetostrictive

Material

Phase-transition dependent

Material

Piezo-

ceramic

PVDF Terfenol-D Nitinol FSMA

Maximum

free strain

(Λ)

in microns

2000 700 2000 20,000 30,000

Young’s

Modulus

(GPa)

60-70 2-3 48 27.5 M-

phase, 90 A-

phase

0.45 – 0.82

Bandwidth 0.1 Hz-

GHz

0.1 Hz-GHz 0.1 Hz-10KHz 0-10 Hz 100 Hz

Traditional VS New ActuatorsDrive Device Displacement Accuracy Torque/Generative

ForceResponse

Time

Air Pressure Motor Rotation degrees 50 Nm 10 sec

Cylinder 100mm 100µm 10-1 N/mm2 10 sec

Oil Pressure Motor Rotation degrees 1000 Nm 1 sec

Cylinder 1000mm 10µm 100 N/mm2 1 sec

Electricity AC Servo Rotation minutes 30 Nm 100 msec

DC Servo Rotation minutes 200 Nm 10 msec

Linear Stepper 1000mm 10µm 300 N 100 msec

Voice-Coil 1mm 0.1µm 300 N 1 msec

Piezoelectric 100µm 0.01µm 30 N/mm2 0.1 msec

Magnetostrictive 100µm 0.01µm 100 N/mm2 0.1 msec

Ultrasonic Motor Rotation minutes 1 Nm 1 msec

Smart Materials as Sensors & Actuators

Input Stimulus

Output Strain

Direct EffectOutput –Electric Potential

Input Stress

Output Signal

Reverse Effect

Input: Electric/Magnetic/ Thermal

Inspirations from Animal Locomotion

Motor based Rigid Robots

Snake Like – ACM R5

Bi-pedal Walking Robot M2Quadruped Stair-climber Titan - 6

Muscle based Flexible Robots

Pneumatic Artificial Muscle (PAM)

Smart Muscles based on Shape Memory Alloys and Electro-active Polymer

What is Shape Memory Effect?

• There are two common shape memory effects - One Way and Two Way effects.

• In the case of One Way effect, the material always remembers the shape at Parent State (Austenite Phase)

• In the case of Two Way effect, the material is trained to remember two shapes, one at the Parent Austenite phase and the other at the Martensite Phase

Hysteresis Curve of SMA

Ms: Martensite start temperature, Mf: Martensite finish temperature, As: Austenite start temperature and Af: Austenite finish temperature

Crystal Structure Depicting SME

One-Way SME

Pseudo-elasticity

Stress-induced Transformation

Metallic Alloys that show SME

• SME was first observed in 1932 in Silver Cadmium Alloy

• Three types of SMA are currently popular– Cu Zn Al– Cu Al Ni and– Ni Ti

• The last one is commercially available as NiTiNOL (NOL – Naval Ordinance Laboratory)

Space Application of SMA:

Control of aerodynamic surfaces

Micro-coils for vibration isolation

Grasping by robotic fingers

Space exploration: rock splitting by ESA

Nitinol filter

Deployment of Solar Array Hinges (EMC)

Advantage of Module-Locking

An SMA based Trajectory Tracking System

An SMA based Sensor

Another SMA based Sensing

Shape Memory Alloy (SMA) based Sensor for Two-Phase Flows

Experiment Results

A Mix of Sensing and Actuation

SMSS Laboratory, IIT Kanpur 35

Experimental Setup:

SMA spring inserts

Metallic stripSMA spring for unlocking

Bearing

Auto locking mechanism

Flexible Antenna System

Self-Healing

Google Solara 50 Crash due to Large Wing Deformation

Source: National Transportation Safety Board Report 2017

Google's solar-powered plane, designed to deliver free internet from the skies, crashed in New Mexico shortly after takeoff.

The unmanned Solara 50 experienced a sudden change in speed that caused its wing structure to deform, and partially collapse leading to a drastic turn which the operator wasn't able to control.

Corrosion Pit triggered Crash of AircraftINTRODUCTION

The M18 Dromader was carrying out water bombing operations for the Rural Fire Service when it crashed near Ulladulla in October 2013.

The final report from the Australian Transport Safety Bureau (ATSB) found the wing separated from the plane due to a fatigue crack in the lower attachment fitting, which was originated from small corrosion pits.

The corrosion pits were not successfully removed during maintenance, and the unapproved inspection method may not have been effective in detecting the crack.

Source: ABC News by Nick McLarenPosted 16 Feb 2016, 3:51am

What is Self-Healing?.

The ability of a material to carry out autonomous healing against damages such as cracks, ruptures or punctures by drawing a healing material either from inside or from an outside source.

All living materials in nature demonstrate this property. Consider the bone…

Ramchandran Plot of Collagen Structure

Self Healing in Plants

6/30ISSS 2017 June 17, 2017

Some Plants are able to heal due to high-level ofdedifferentiation, a process whereby mature cellswithdraw from their specialized role and acquireproliferation ability and Pluripotency, enabling them todevelop anew into different cell types like the Hypocotyls.

Strategies for Self Healing: Encapsulated Healing Material

Passive Technique: DCPD based Autonomic Self Healing proposed by White et al (2000)

Healing is accomplished by incorporating a microencapsulated healing agent and a catalytic chemical trigger within an epoxy matrix. An approaching crack ruptures embedded microcapsules, releasing healing agent into the crack plane through capillary action. Polymerization of the healing agent is triggered by contact with the embedded catalyst, bonding the crack faces. The damage-induced triggering mechanism provides site-specific autonomic control of repair.The reaction polymerizes dicyclopentadiene (DCPD) at room temperature in several minutes to yield a tough and highly cross-linked polymer network. DCPD-filled microcapsules (50–200 µm) with a urea-formaldehyde shell were prepared using standard microencapsulation techniques.

Strategies for Self Healing by using Activated Hydrogels

Due to the nature of Supramolecular polymers, the non-covalent interactions make supramolecular polymers more dynamic and reversible. Such properties enable supramolecular polymers to construct a dynamic and reversible network, which are able to develop self-healing materials based on noncovalent bonds. Compared with self-healing materials based on covalent bonds, these supramolecular polymer-based self-healing materials can restore the initial structure and function of polymers before being exposed to damages, and can also undergo repeating damage-heal process.

1 10 100100

101

102

3.97 %

G'/G

''

%strain

G' G''

Arindam et al (2014)

Strategies for Self HealingPassive Technique: Vascular Self-Healing

Requires special PTFE 3D Micro-channels for spreading the Healing Agent with Acetonitrile.

In case of rapture, the low viscosity MDI flows out.

Presence of moisture is essential as the Viscosity of MDI increases in reaction with water.

Damage initiates Polyureaformation. Once enough Polyureaformation takes place, the moisture level comes down and the MDI-Acetonitrile solution continues to flow in the vascular system.

Issues with Intrinsic Self Healing1. Generally, healing is initiated passively and does not detect the damage at an early stage and initiate healing.2. Self-healing is typically an open loop process with no regulation of the healing process to counteract the onset of damage. As a result, the process might be unableto achieve the desired healing response and handling of uncertainty/disturbance isalso likely to be poor.3. There is usually no controllable mechanism to terminate the process. For example, healing agent stops bleeding into the damaged zone when flow is restricted.

Extrinsic Self-healing

Regulating the healing rate involves controlling factors that can affect the reaction kinetics of a healing process.

Factors such as the speed of delivery/mass flow rate, release mechanism, temperature, catalyst, pressure, concentration and pH level may vary from system to system.

Sensor Type Damage type

Self-Healing Material

Pressure Delamination Vascular GFRPFibre Optics Delamination Vascular CFRPPhotoResistor

Cracks Intrinsic TP

Acoustics Emission

Cracks Vascular Epoxy

In search of a Solid Self-healing Agent

Similar to Bone: A Mechanism is proposed based on Redistribution of Structural Mass in response to Stress Gradients in a Dynamic Environment.

Electrochemical Redistribution triggered by Voltage Generation due to change in stress-field

Poly vinylidene fluoride-cohexafluropropylene(PVDF-HFP), zinc oxide and copper nanoparticles are mixed together to form a PVDF-HFP solid electrolyte. Carbon fibre reinforcement and the PVDF-HFP solid electrolyte are combined to form composite laminates and held together by bolts which also act as electrodes.

Extrinsic Self-healing

Because of the high density of fluorine groups, PVDF-HFP has a high coordinating ability with many metal ions; this leads to relatively high levels of ionic conductivity. Fluorine can further form H-bonds, which provide the system with pseudo cross-linking and thus enhance mechanical attributes.

Extrinsic Self-healing Concept using Smart Sensor

Future Scope of Advancement Improvement of Passivation Strength vs Reversibility Integrate the system in a composite structure Integrate with Predictive Prognosis Capability Supply of Healing Material Identification of Critical Healing Regions

Future of Smart Polymers

• Higher ‘IQ’ – ‘responsiveness’ –larger actuation corresponding to smaller stimulation, ‘agility’ –faster response – increasing the bandwidth of the existing smart materials

• Higher order ‘functionality’- self-sensing, self-actuation, self-healing, auto-phagous, energy harvesting, energy scavenging

• Exploit the success in ‘nano -technology’ and develop more ‘varied’, ‘complex’ and ‘intelligent systems’

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