Equivalent single layer theories with layer-independent primary displacement variables are not capable of accurately predicting the transverse shear stresses directly from the constitutive equations. The prediction is particularly poor for the thermal loading. The transverse shear stresses are, however, often responsible for weak interfaces and delamination in such laminates. The authors have recently developed an improved global-local theory (IGLT) with eleven displacement variables and a zigzag-local theory (ZLT) with nine displacement variables for hybrid plates with a view to overcome this limitation. In these theories, the normal deformability under thermoelectric loading is accounted for without introducing any additional deflection variables. In this study, we assess the performances of the two theories with and without the normal extensibility terms, under thermoelectric loading. The assessment is performed for patch type thermal loading in direct comparison with the three dimensional (3D) piezothermoelasticity solutions for a variety of hybrid composite and sandwich plates.

Keywords: Global-local theory, Laminated smart composite, Thermal load and Transverse stresses.