Sublaminate variable kinematics shell models for functionally graded sandwich panels: Bending and free vibration response

An advanced kinematic formulation is applied to multilayered cylindrical sandwich panels with continuously graded layers. Free vibration and bending problems are considered. The mean mechanical properties of the composite material are estimated by means of the extended rule of mixture or the Eshelby-Mori-Tanaka method. The displacement field is postulated by means of variable-kinematics sublaminate models, therefore the applicability is not restricted to monolithic panels, on the contrary, the approach is well suited for sandwich panels with marked thickness-wise heterogeneity. Due to the efficiency of the formulation, the effect of various design parameters, either geometrical or mechanical, can be easily explored. The validation is performed against benchmarks of increasing complexities, namely a single-layer square plate, a shell reinforced by randomly oriented nanotubes, sandwich panels with three distinct configurations. The importance of allowing kinematic descriptions of tunable accuracy within a unique framework is well demonstrated by the proposed assessments.