Smart materials

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SMART MATERIALS AND SYSTEMS

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Smart materials

  1. 1. SMART MATERIALS AND SYSTEMS BY JOBIN JOY ASSISTANT PROFESSOR DEPARTMENT OF ME SBCE
  2. 2. SCIENTIFIC ACHIEVEMENTS THAT THE WORLD HAS MADE SINCE THE BEGINNING OF HUMAN CIVILIZATION • Up to 1760-:Very little scientific activity • 1769 -:James watt invented steam engine. • 1800-1900-:Age of industrialization • 1900-2000-:Age of information • After 2000-: Age of decision
  3. 3. SMART MATERIALS-WHY THIS NAME? SMART 1. Suggesting vigour,speedy,spirited,lively 2. Showing mental alertness and INTELLIGENT 1. To perceive ones environment 2. To know/comprehend and learn 3. To understand quickness of 4. To foresee problems perception,shrewd,resourceful 5. To think abstractly. 3. Sharp
  4. 4. DESIRABLE ATTRIBUTES OF A SYSTEM Smart, Intelligent sense-able, adaptive, organic, controlled Material, structures, systems, products 24 combinations
  5. 5. SMART SYSTEMS-DEFINITION • Integration of functions( Sensor , Actuator and Control mechanisms) • Stimulus • Response A system which has intrinsic sensor, actuator and control mechanisms whereby it is capable of sensing a stimulus, responding it and reverting to its original state after the stimulus is removed
  6. 6. SMART MATERIAL-DEFINITION • Material which has the intrinsic or extrinsic capabilities to respond to an external stimulus in a functionally useful manner. • E.g. : Zinc oxide varistors (ZNO)
  7. 7. SMART MATERIALS-EFFECTS • Also called functional materials • A material can be considered smart when a input stimulus of a variable changes the output of other variables not given as input OR A material is smart if a specific response is produced to a combination of inputs.
  8. 8. SMART MATERIALS-EFFECTS • Actuator effect (Converse effect) Electrical, thermal, optical, magnetic input Mechanical action
  9. 9. SMART MATERIALS-EFFECTS SENSOR EFFECT(DIRECT EFFECT) Electrical signal Mechanical input
  10. 10. MAIN ADVANTAGES RESPECT TO TRADITIONAL COMPONENTS a) act simultaneously as sensors and actuators b) Perform controlled mechanical action without any external mechanisms c) Are adaptive with the environmental conditions d) High level of miniaturization e) New functions development
  11. 11. SMART SYSTEMS-DEFINITION • SMART STRUCTURE A smart structures integrates the properties of embedded sensors, actuators and control mechanisms in order to respond to a given stimulus in a functionally useful manner. Usually this involves implementing hardware and or software control mechanisms.
  12. 12. Need for smart systems i. Optimizing response of large complex systems ii. Perform enhancements otherwise not possible iii. Functionality
  13. 13. SCHEMATIC OF A SMART STRUCTURE STRUCTURE FORCE ACTUATOR SENSOR DISTURBANCE CONTROLS CONTROLLER
  14. 14. IDEAL SMART STRUCTURE SENSOR-SKIN/NERVES • Distributed and integrated • Sense temperature, humidity stress,force,pressure etc ACTUATOR-MUSCLES/NERVES • Distributed and integrated • Generate shape, force and motion • Change stiffness and damping level. DECISION /CONTROL-SERVES/GENETICS • Distributed/hierarchical • Local level decision/actuation • High level communication with brain ADDITIONAL FEATURES • Self breeding • Self healing/repairing • Self diagnosis
  15. 15. COMPARISON WITH BIOLOGICAL STRUCTURES • • • • Useful strength to weight ratio Self repairing systems Adaptive joining mechanisms(mainly muscles and tendons) Processing is distributed with central monitoring systems(brain) • Communication channels throughout the systems(neurons) • Central processor is highly adaptive and self configures in the light of experience • Energy transfer mechanisms involve chemically burned distribution systems.
  16. 16. SMART SYSTEMS RESEARCH • Smart systems is a multidisciplinary area requiring understanding of  Materials  Electronics  Signal processing  Control
  17. 17. SMART MATERIAL RESEARCHUNDERSTANDING OF DIFFERENT DOMAINS a) b) c) d) e) f) g) h) i) j) k) Mechanics and structurures Control and processing MEMS Electro mechanics Dynamics and vibrations. Materials and systems. Computer hardware and software. Mathematics. Manufacturing and quality control. Design optimization Mechatronics
  18. 18. SMART SYSTEMS EXPERTISE SYSTEMS ENGINEERING MATERIAL SCIENCE APPLIED PHYSICS SMART SYSTEMS ELECTRICAL ENGINEERING MECHANICAL ENGINEERING
  19. 19. WHAT CONSTITUTES A SMART SYSTEM • Mechanical structures • Sensors • Actuators • Controllers • Signal processing and data reduction
  20. 20. Components of smart system SENSOR • To monitor environment changes and generate signals proportional to the changing measurand ACTUATOR • The actuators are used to change the properties of the smart structure in order to achieve the desired response CONTROL SYSTEM • The control system continuously monitors the sensors signal, processing the information in order to determine if action is required ,if an action is required then a signal is applied to the appropriate actuators.
  21. 21. SMART STRUCTURES CLASSIFICATION • PASSIVELY SMART (eg:fibre optic sensor) • Structures have the ability to respond to a stimulus in a useful manner without assistance of electronic controls or feedback systems. • ACTIVELY SMART. • Structures utilize feedback loops which accelerate the recognition and response process. • VERY SMART(OR INTELLIGENT). • Structures utilize the nonlinear property of the sensor,actuator,memory and or feedback systems to tune the response behavior
  22. 22. Actuators consideration • A number of different actuators can be incorporated into a smart structure in order to generate the appropriate response to a detected environmental variation. This type of actuator is dependent on a number of parameters.
  23. 23. • NATURE OF ACTUATION • Optical,magnetic,thermal,mechanical, • chemical etc. • NATURE OF DRIVING AGENCY • Thermal,magnetic,electrical,chemical etc • ENVIRONMENTAL CONSIDERATIONS • Corrosion,thermal,magnetic,electrical etc
  24. 24. • • • • INTERFACING Size,geometry,mechanical properties etc. PROPERTIES OF THE ACTUATOR Displacement, force generation,hysteresis,response time, bandwidth etc.
  25. 25. SENSOR CONSIDERATION • A number of different sensors can be incorporated into a smart structure to measure a number of different environmental variations.the type of sensor utilized in smart structures is dependent on a number of factors.
  26. 26. SENSOR CONSIDERATION • NATURE OF MEASURAND • Radiation,magnetic,thermal,mechanical,chemical etc • SENSOR OUTPUT • Thermal,magnetic,electrical,optical mechanical etc • ENVIRONMENT • Corrosive,thermal,magnetic,electrical etc
  27. 27. SENSOR CONSIDERATION • INTERFACING • Size,geometry,mechanical properties • OPERATIONAL PROPERTIES • Sensitivity,bandwidth,linearity,gauge length, operational range etc.
  28. 28. Smart control system • The smart control system will provide feedback control for the sensors and actuators • The scs will include the interfaces necessary for the operation of the subsystem modules.
  29. 29. SMART CONTROL SYSTEM THE SCS WILL CONSIST OF THE FOLLOWING • Analogue to digital and digital to analogue converters. • Input signal amplification and filtering. • Control algorithm. • Digital signal processing(DSP) • Output power supply.
  30. 30. APPLICATION OF SMART SYSTEMS • Aerospace • Defence • Automotive • Industrial • Medical • Civil
  31. 31. SMART MATERIAL TYPES • Piezoelectric materials • Optical fibers • Shape memory alloys (SMA) • Electro active materials • Electro magneto rheological fluids • Carbon Nanotubes
  32. 32. PIEZOELECTRIC MATERIAL • It possesses the property of converting mechanical energy into electrical energy and vice versa.
  33. 33. Piezoelectric materials • Mechanical stress electrical field Potential field : SENSOR(DIRECT EFFECT) • Electric field mechanical strain ACTUATOR(CONVERSE EFFECT)
  34. 34. PIEZOELECTRIC SENSOR • When mechanical stresses are applied on the surface, electric charges are generated (SENSOR EFFECT) • If those charges are collected on a conductor that is connected to a circuit, current is generated.
  35. 35. PIEZOELECTRIC ACTUATOR • When electric potential (voltage) is applied to the surface of the piezoelectric material, mechanical strain is generated (ACTUATOR) • If the piezoelectric material is bonded to a surface of a structure, it forces the structure to move with it.
  36. 36. FORMS OF PIEZO MATERIALS • 1-3 piezocomposites • Active fiber composites 1. CRYSTALS 2. PZT(actuator material) 3. PVDF(sensing material)
  37. 37. FIBER OPTIC SENSORS • Works on the principle of total internal reflection. • All light energy will be completely reflected. • It essentially sensor material. It cannot do any actuation. • When the system in which these fibers are embedded undergoes any change, then the incident wave length of the light undergoes a physical shift, which indicates the change the system.
  38. 38. COMPONENTS OF FIBER OPTIC SENSOR a) Source of light b) Length of sensing fiber c) Photo detector d) Demodulator e) Processing and display optics f) Electronics
  39. 39. TYPES OF FIBER OPTIC TYPES BASED ON MODULATION OR DEMODULATION • Phase sensor • Frequency sensor • Polarization sensor
  40. 40. BASED ON APPLICATION OF FOS • Physical sensor • Chemical sensor • Biomedical sensor
  41. 41. MODE OF SENSING • Extrinsic sensor • Intrinsic sensor
  42. 42. ELECTROSTRICTIVE MATERIALS • Principle materials-LEAD MANGANESE NIOBATE:LEAD TITANATE(PMN-PT) • LEAD LANTHANUM ZIRCONATE TITANATE(PLZT) • This is used for actuation purpose only. • Suitable for frequencies up to 50khz • E=700GPA and very brittle • Fast response time. • Low hysteresis loop and hence low loss material.
  43. 43. MAGNETOSTRICTIVE MATERIALS • Eg:TERFENOL-D (alloy of Terbium, iron(FE)) • Phenomenon similar to electrostriction • Can be used for both sensing and actuation • Rarest of the rare earth material. and hence very expensive • Large strain levels(2%) • E=200gpa and length of 200mm. • Narrow hysteresis loop and hence low loss • Generates large actuating force(order of kilonewtons)
  44. 44. SHAPE MEMORY ALLOY (SMA) • Change mechanical properties with the change of temperature • Regain its original shape when heated • Normal temperature-one phase • Temp increases-changes its phase and retains the memory. • Main disadvantage is slower response time
  45. 45. SHAPE MEMORY ALLOYS(SMA) • • • • • • made by nixing nickel and titanium T<TC, Martensitic phase-plastic state-large strains can be applied with little stress. T>TC, Austenitic phase-memory phase-retains its original shape. Actuation is caused by transforming the material from martensite to austenitic phase. This process causes enormous amount of stress, which can be used for actuation purpose. Slow reaction time Properties depend on the composition, the phase and past history.
  46. 46. ELECTRO-RHEOLOGICAL FLUID. (ER FLUID) • Viscous properties are modified by applying electric fields • Obtained by mixing SILICONE OIL AND CORN STARCH. • In the neutral state particles are uniformly distributed. Under electric field the large dielectric constants redistributes the particles changing the viscous properties. • E R fluid are non Newtonian fluids. • Useful in transforming shear stresses
  47. 47. ER FLUID ELECTRIC FIELD APPLIED • ELECTRIC FIELD REMOVED ER FLUID ER FLUID CHANGES LIQUID TO SOLID CHANGES FROM SOLID TO LIQUID
  48. 48. MAGNETO RHEOLOGICAL FLUIDS (MR FLUID) • LITHIUM GREASE MIXED WITH MICRON SIZED IRON PARTICLES. • Externally applied magnetic field in a direction normal to the fluid flow direction from dipoles in the iron particles. • Magnetic poles start attracting each others to the direction of the field hence forming chains. • The chains then form a skeleton within the fluid, which gains the fluid controllable yield stress.
  49. 49. MR FLUID MAGNETIC FIELD APPLIED • MAGNETIC FIELD REMOVED MR FLUID MR FLUID CHANGES TO LIQUID TO SOLID CHANGES FROM SOLID TO LIQUID This property can be used in changing the damping characteristics of a damper
  50. 50. THANK YOU

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