Improved global-local theory for laminated plates under thermal load with actual temperature profile

The global-local theory (GLT) differs from other laminate theories with layer-independent degrees of freedom in that it can predict with good accuracy the transverse shear stresses directly from constitutive equations, while others cannot. In this work, an improved global-local theory is presented for laminated plates under thermal loading, which takes into account the actual temperature profile across the thickness, obtained by solving the heat conduction equation, and incorporates the transverse thermal strain in the deflection field without introducing any additional deflection variable. The temperature field is approximated as piecewise linear across an arbitrary number of sub-layers. The assumption of constant deflection across the thickness in the existing GLT is augmented by superimposing the contribution from the transverse thermal expansion, following the method proposed by Kapuria et al. [15 S. Kapuria , P. C. Dumir , and A. Ahmad , An Efficient Higher Order Zigzag Theory for Composite and Sandwich Beams for Thermal Load , Int. J. Solids Struct. , vol. 40 , pp. 6613 – 6631 , 2003 .[CrossRef], [Web of Science ®], [Google Scholar]]. It fulfils the continuity condition of the deflection field a priori. The governing equations and variationally consistent boundary conditions are derived using the principle of virtual work. The improved and existing GLTs are assessed in direct comparison with the three dimensional elasticity solution and also with other available theories, for a variety of inhomogeneous composite and sandwich plates