Résumé:
The aim of this work is to develop a new quasi-3D high order shear deformation theory to study
the bending behavior of simply supported functionally graded sandwich beams (FGSBs), subjected
to nonlinear hygro-thermo-mechanical loadings. The analysis focuses on symmetric and
asymmetric sandwich beams, with skins made of functionally graded material. In addition, the
influence of transverse stretching is considered in this study. The material properties, thermal
expansion and moisture concentration coefficients vary gradually and continuously according to a
power-law distribution (P-FGM) in terms of the constituent volume fractions. The proposed model
adopts a new field of displacement that includes indeterminate integral variables and contains only
four unknowns. The equilibrium equations are derived using the principle of virtual work and
solved using the Navier's technique. Furthermore, the nonlinear hygro-thermo-mechanical
coupling loading (NL-HTMCL) is integrated into these equations. The results obtained show a
strong correlation between the non-dimensional stresses and displacements compared to those
obtained from other 3D and quasi-3D theories, which demonstrates the efficiency and accuracy of
the present theory. A parametric study is provided and discussed in detail in this thesis, quantifying
dimensionless terms such as deflection, axial displacement, and stresses, while highlighting the
effects of thermal and moisture loads.
