IMPROVED SMEARED AND ZIGZAG THIRD-ORDER THEORIES FOR PIEZOELECTRIC ANGLE-PLY LAMINATED CYLINDRICAL SHELLS UNDER ELECTROTHERMOMECHANICAL LOADS

An improved efficient zigzag theory (IZIGT) and an improved third-order theory (ITOT) are presented for hybrid piezoelectric angle-ply composite circular cylindrical shells under electrothermomechanical loading. In both theories, the potential and thermal fields are approximated as piecewise linear across a number of sublayers so that the nonlinear potential field and actual temperature profile across the laminate thickness can be captured to any desired degree of accuracy. The transverse displacement is approximated to explicitly account for the transverse normal strain resulting from thermal and electric fields without introducing additional unknowns. The shear traction free conditions on the top and bottom surfaces in both theories and the continuity of transverse shear stresses at layer interfaces in the IZIGT are satisfied exactly considering coupled constitutive equations. The theories are assessed in comparison with the available exact 3D piezothermoelasticity solution for simply supported angle-ply hybrid cylindrical panels under electrothermomechanical loads. The comparisons for a hybrid test panel, a composite panel, and a sandwich panel establish that the IZIGT is very accurate and the ITOT is an improvement over the conventional third-order theory for thermal loads, which assumes uniform deflection across the laminate thickness.