Proceedings of the 22 th National and 11 th International ISHMT-ASME Heat and Mass Transfer Conference December 28-31, 2013, IIT Kharagpur, India HMTC1300415 ACTIVE DAMPING OF SMART FUNCTIONALLY GRADED SANDWICH PLATES UNDER THERMAL ENVIRONMENT USING 1-3 PIEZOELECTRIC COMPOSITES R. Suresh Kumar Dept. of Mechanical Engineering Indian Institute of Technology Kharagpur (WB) 721302, India rsureshiitkgp@mech.iitkgp.ernet.in S. I. Kundalwal Dept. of Mechanical Engineering Indian Institute of Technology Kharagpur (WB) 721302, India sikundalwal@iitkgp.ac.in M. C. Ray Dept. of Mechanical Engineering Indian Institute of Technology Kharagpur (WB) 721302, India mcray@mech.iitkgp.ernet.in ABSTRACT The present study is concerned with the active control layer damping (ACLD) of the geometrically nonlinear vibrations of the smart functionally graded (FG) sandwich plates subjected to the thermal loading. The constraining layer of the ACLD treatment is considered to be made of the vertically/obliquely reinforced 1-3 piezoelectric composite (PZC) while the viscoelastic material is modeled by using the Golla–Hughes– McTavish (GHM) method in the time domain. A three dimensional coupled nonlinear electromechanical finite element (FE) model has been developed based on the first order shear deformation theory (FSDT) and Von Karman type nonlinear strain displacement relations to investigate the damping characteristics of the FG sandwich plates subjected to the thermal loading. Several FG sandwich plates with different thermal loading conditions have been investigated to evaluate the numerical results. Effects of metal or ceramic rich bottom surfaces subjected to the thermal loading, the variation of power-law index on the control authority of the ACLD patches have been thoroughly investigated. Emphasis has also been placed on investigating the effect of the variation of piezoelectric fiber orientation angle on the performance of the ACLD patches for controlling the geometrically nonlinear transient responses of FG sandwich plates. LIST OF ABBREVIATIONS ACLD Active Constrained Layered Damping FGM Functionally Graded Material FE Finite Element FSDT First Order Shear Deformation Theory PZC Piezoelectric Composite GHM Golla-Hughes-McTavish NOMENCLATURE  Length (m) of the sandwich plate b Width (m) of the sandwich plate  Thickness of the substrate sandwich plate  Applied control voltage ℎ Thicknesses of the top and bottom facing ℎ  Half the thickness of the core ℎ  Thickness of the viscoelastic layer ℎ  Thickness of the 1-3 PZC layer  Power law index  Number of ACLD patches   Performance index  Piezoelectric fiber orientation angle (deg) in the 1-3 PZC layer , ,  Cartesian coordinates  0 ,  0 ,  0 Translational displacements (m) at any point on the mid plane along ,  and  directions (  ,   ,   ) Displacement fields ,  and  directions, respectively at any point in the core (  ,   ,   ) Displacements ,  and  directions at any point in the bottom facing (  ,   ,   ) Displacements ,  and  directions at any point in the top facing (  ,   ,   ) Displacements ,  and  directions at any point in the viscoelastic layer (  ,   ,   ) Displacement ,  and  directions at any point in the 1-3 PZC layer   ,   ,   ,   ,   Rotations (rad) of the normals about the mid planes of each layer about the − axis