Smart Materials
     • Materials with coupled properties in two (or 
        more) physical domains that are used to sense 
        or control behavior 
     • Physical domains?                      • Mechanical
           • Electrical                            -  Thermal
               -   Ferroelectrics             • Magnetic
               -   Piezoelectrics                  -  Shape Memory Alloys (SMA)
               -   Electrorheologic                -  Thermal expansion 
           • Magnetic                         • Multiferroic
               -   Ferromagnetic SMA               -  coupled ferroelectric and  
               -   Magnetostrictives                  magnetostrictive domains 
               -   Magnetorheologic           • Ionic gradient (”Nastic”)
           • Optiical                         • Pneumatic Artificial Muscle
          Example of Physical Domains
                                     Output
     Input     Current   Magneti-    Strain    Temper-  Light
               (charge)   zation                ature
   Electric   Conductiv
   field      ity
   Magnetic              Permeabil
   field                 ity
   Stress                          Elastic 
                                   Modulus
   Heat                                       Specific 
                                              heat
   Light                                                 Refractive 
                                                         index
     + Transduction to a different domain
                                     Output
     Input     Current   Magneti-    Strain    Temper-  Light
               (charge)   zation                ature
   Electric                                              Electro-
   field                                                 optic
   Magnetic                                              Magneto-
   field                                                 optic
   Stress                                                Photo-
                                                         elastic
   Heat                                                  Thermo 
                                                         Lumin-
                                                         ecence
   Light      Photo-     Photo-    Photo-     Photo- 
              voltaic    magneti-  striction  thermal 
                         zation               effect
                 State of art smart materials
                                                      Output
       Input         Current        Magneti-            Strain        Temper-  Light
                    (charge)          zation                            ature
    Electric                                        Inverse 
    field                                           Piezo-electric 
    Magnetic                                                                        Magneto-
    field                                           Joule effect                    optic
    Stress          Piezo-                                           Thermo-
                    electric      Villari  effect                    mechanica
                    effect                                           l effect
    Heat                                            Thermal 
                                                    expansion 
                                                    &/or Phase 
                                                    transition
    Light                         Photo 
                                  magnetizaton
        Example: Linearized model of 
              Magnetostriction
    • “A change in dimensions exhibited by 
     ferromagnetic materials when subjected to a 
     magnetic field.” (Random House Dictionary)
    • Documented by James Joule in 1842
    • Linear 1-D magnetostriction model:
       
             /EH dH T
                   y
                *     
                           +
           Bd HPT