Hygrothermoelastic analysis of multilayered composite and sandwich shells

Refined two-dimensional models are proposed for the static hygrothermoleastic analysis of multilayered composite and sandwich shells. These shell models are developed in the framework of the Carrera's unified formulation (in a general and unified manner) by considering both equivalent single layer and layerwise multilayer description. The principle of virtual displacements contains elastic, thermal and hygroscopic strains. The governing equations allow mechanical, thermal and hygroscopic loads to be applied and they are solved in a closed-form solution. Thermal and hygroscopic loads are defined by means of appropriate temperature and moisture content profiles through the thickness of the shell, such profiles can 'a priori' be assumed or they can be calculated by solving the Fourier heat conduction equation and the Fick's moisture diffusion law. Such equations are solved in steady-state conditions and in curvilinear coordinates for the shell geometries. The presence of loads due to hygroscopic and thermal effects (in addition to the mechanical load) modifies the bending response of multilayered shells. Comparisons between classical and refined models, and between assumed and calculated temperature and moisture content profiles are proposed in the cases of composite and sandwich shells. The use of refined models combined with calculated temperature and moisture content profiles through the thickness is mandatory for a correct elasto-thermo-hygroscopic analysis of multilayered structures.