Module 1 MSD (Theory sessions 3 & 4) PDF

Introduction to smart materials “A material that reacts quickly to a stimulus in a specific manner with the change in material property being reversible” Salient features  Response of a smart material to an external Smart is: stimulus is same every time  Removal of...

Introduction to smart materials “A material that reacts quickly to a stimulus in a specific manner with the change in material property being reversible” Salient features  Response of a smart material to an external Smart is: stimulus is same every time  Removal of stimulation causes complete  Significant (S) reversibility to original state  Measurable (M)  Different smart materials respond only to different specific stimuli  Appropriate (A)  The unique specific stimuli versus predictable  Result Oriented (R) response render them potential candidates for novel applications  Time oriented (T) Smart materials significantly alter one or more of their inherent properties in response to a suitable, external stimuli in a controlled fashion L#3 Examples for smart materials & Applications Smart material Stimuli Response Applications Piezoelectric Deformation PD* Strain gauges, oscillators, gas lighters Electrostrictive PD* Deformation Acoustic generators, underwater sonar devices Magnetostrictive Magnetic field Deformation Real-time monitoring of railroad suspension components, biomedical applications Thermoelectric Temperature PD* Electricity generation, refrigeration/ air conditioning, biomedical devices Shape memory alloys Temperature Deformation Braces & dental arch wires, prosthetic, robotic hands, vibration damping Photochromic Radiation Colour change Optical switches, data storage devices, energy-conserving coatings, eye-protection glasses & privacy shields Thermochromic Temperature Colour change Thermal sensors-ink/textile/reactors Electrochromic PD* Colour change Anti-glare car rear-view mirrors, smart sunglasses, optical information storage Ferrofluids Magnetic field Temperature, Biosensing & medical imaging, hyperthermia Viscosity for cancer treatment, sealants MR fluids Magnetic field Viscosity Automotive industry, household applications, prosthetics, civil engineering, ER fluids PD* Viscosity hydraulics, brakes and clutches (non-exhaustive list) L#3 PD* is potential difference Impetus to growth of smart structures Recent advances in materials science Improved sensor and actuator technologies [Source: B. Bhattacharya & N. Tiwari, Department of Real-time information processing Mechanical Engineering, IIT Kanpur] Tape casting and screen printing technologies Integration and miniaturization https://www.grandviewresearch.com/industry-analysis/smart-materials-market L#3  Traditional versus Smart structures Traditional structures Smart Structures Designed for certain performance Can self-adjust to varying requirements (Ex: Load, Speed, Life performance requirements span) (to certain degree) Unable to modify performance Can accommodate unpredictable specifications if there is a change of environments environment Efficiency of operation is limited Offers highly efficient operation Limited applications per a traditional Wide range of applications possible structure for a given smart structure L#3 Smart material: ‘Degree of smartness’ Active smart materials* [*seen in detail in subsequent classes….] Materials which can inherently transduce energy Eg: Piezoelectric, SMAs, MR & ER fluids, Magnetostrictive materials etc. Passive smart materials Materials which lack the inherent capability to transduce energy Eg: Fiber optic material John Tyndall, a British Physicist demonstrated light could be guided through a stream of water Concept of ‘bending of light’: ‘Wave property’  Advent of LASERs (1960; Maiman) & superior quality glass fibers:  Feasibility of optical fiber communication (OFC) L#3 Optical fiber - The passive smart material A bundle of Optical Fibers Schematic A single Optical Fiber Cable containing many Optical Fibers Principle: Snell’s law: n1sinθ1=n2sinθ2 Total Internal Reflection (TIR) Used as light waveguides in the optical communication system L#3 Optical fiber for Communication technology Optical Fiber Communication (OFC): Point to Point Communication System Block Diagram L#3  Types of Active Smart Material: State of the m at t er Liquid state - Magnetorheological fluid - Electrorheological fluid - Ferrofluid Solid state - Shape memory alloys - Magnetostrictive materials - Piezoelectric materials Soft matter - Liquid crystals - Shape memory polymers - Conducting polymers - Hydrogels, Superhydrophobic materials, Colloids and Surfactants [Non-exhaustive, but sufficient list] L#4 Smart fluids: Liquid -state smart materials Magnetorheological & Electrorheological fluids; Ferrofluids (Please note that only magnetorheological fluid will be discussed in detail) Magnetorheological fluid (MRF): “A smart fluid with soft magnetic mesoparticles suspended in a non-magnetic carrier liquid, showing dramatic increase in apparent viscosity on application of a magnetic field to the extent of becoming a visoelastic solid” Jacob Rabinow Ferrofluids are similar to MRF, except that magnetic particles are nanosized. Ferrofluids find application in hyperthermia Electrorheological fluids (ERF) are similar to MRF, except that the stimulus is electric field and particles are dielectric. Applications are the same as that of MRF L#4  Smart fluids: Magnetorheological fluid (MRF) Response of MRF under applied field and Behavior of solids shear conditions (schematic representation) versus MRF MRF under (a) no applied field condition, (b) with applied field and no stress acting, (c) with applied field and external shear stress of low magnitude and (d) shear stress exceeding strength imparted by applied field, yielding the Stress (τ) versus strain (γ) MRF. The magnetic particles are represented as green spheres  Electrorheological fluids are similar to Magnetorheological fluids in all aspects; except that the stimulus is electric field in the former compared to the magnetic field in the latter  Ferrofluids are similar to Magnetorheological fluids, however, employ nanomagnetic particles instead of micromagnetic particles. Thus response of ferrofluid is weaker L#4 Magnetorheological fluids -Applications Present/Potential/Novel prototypes Seat suspension damper AWD clutch Shock absorber (Lord Corp., NC) (delphi magneride) HUMVEE* The Dong Ting Lake Bridge (China) (Lord Corp) Prosthetic knee-rotor damper Space application - fuel slosh control Earthquake-proof buildings Zoom view of ring baffle Stand-alone seismic damper Darrell staaleson, kent, WA MRF slosh damping for ring baffle in ext. Galaxy Messier 100 (~ 55MLy) tank (NASA) L#4 Hubble telescope, NASA * HUMVEE: High Mobility Multipurpose Wheeled Vehicle (HMMWV; colloquial: Humvee) Smart fluids: Electrorheological fluids Electrorheological fluid (ERF): “A smart fluid with dielectric mesoparticles suspended in an insulating (non-conducting) carrier liquid, showing dramatic increase in apparent viscosity on application of an electric field to the extent of becoming a visoelastic solid” https://sheng.people.ust.hk/?p=120 Invented by: Willis Winslow; 1947 Suspended particles are dielectric materials such as SiO2 Applications are similar to that of MRF; debatable on the ease of use MRF versus ERF  MRF exhibits higher yield strength in comparison to ERF  ERF requires very high voltage source! L#4  Smart fluids: Ferrofluids Ferrofluids (FF): “A colloidal liquid made of nanoscale ferromagnetic or ferrimagnetic particles suspended in a carrier fluid (usually an organic solvent or water)” https://en.wikipedia.org/wiki/Ferrofluid FF is similar to MRF; however, employs nanoparticles instead of microparticles Steve Papell; for NASA in 1963 FF is highly stable since it is colloidal rather than a suspension FF has lower magnetic response than MRF; in turn, the applications are different for these two classes of magnetic fluids Applications:  Rotary seals in computer hard drives and other rotating shaft motors  In loudspeakers to dampen vibrations  In medicine as a contrast agent for magnetic resonance imaging (MRI)  Magnetic hyperthermia for cancer treatment Further reading: L. Vekas, Advances in Science and Technology, 54, 127-136 (2008), Trans Tech Publications, Switzerland L#4  Smart fluids: A comparison Ref: Kumbhar, Nilesh & Patil, Satyajit. (2014). A study on properties and selection criteria for magneto- rheological (MR) fluid components. International Journal of ChemTech Research. 6. 3303-3306. L#4 End of theory sessions 3 & 4