Contribution à l’étude du comportement statique des structures en matériaux avancés sous chargements couplés non linéaires

Abstract

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.