An efficient higher order zigzag theory for composite and sandwich beams subjected to thermal loading

A new efficient higher order zigzag theory is presented for thermal stress analysis of laminated beams under thermal loads, with modification of the third order zigzag model by inclusion of the explicit contribution of the thermal expansion coefficient α₃ in the approximation of the transverse displacement w. The thermal field is approximated as piecewise linear across the thickness. The displacement field is expressed in terms of the thermal field and only three primary displacement variables by satisfying exactly the conditions of zero transverse shear stress at the top and the bottom and its continuity at the layer interfaces. The governing equations are derived using the principle of virtual work. Fourier series solutions are obtained for simply-supported beams. Comparison with the exact thermo-elasticity solution for thermal stress analysis under two kinds of thermal loads establishes that the present zigzag theory is generally very accurate and superior to the existing zigzag theory for composite and sandwich beams.