Analytical solutions for large-deflection bending of variable-thickness inhomogeneous functional graded composite circular plates with parameterized boundaries under hygro-thermo-mechanical loads

A brand-new hygro-thermo-mechanical bending model of the inhomogeneous concave and convex composite circular plates having varying thickness undergoing large deformation resting on nonlinear tri-parameter spring and shear elastic layers is proposed. Three-dimensional analytical hygrothermal field of circular plate is demonstrated with non-uniform thermal and moisture diffusion coefficients in axial variation, while thickness and elastic module of material are modeled in quadratically change and sufficiently summarized in normalization. The circled boundaries with arbitrary translational and rotational constraints are parameterized with feasible region of elastic parameters highlighted in rectangular domain by Linear Programming method. Two reduced-order integro-differential governing equations for the composite circular plates under extreme load have been derived, while analytical bending solutions are obtained by an employed homotopy-based analytical scheme with accuracy verified and convergence accelerated by truncation and iteration. Whether thickness or elastic module of composite material is variable, the final outcome on plate structural strength is the discrepancy of bending stiffness with different load capacity, with the former revealing more sensitive than the latter under the condition of same values. Once amplitude and distribution of hygrothermal load are determined, influence on large-deflection bending of circular plates exists at a limited range of nonlinearity, while non-uniform distribution of thermal expansion and moisture concentration aggravates bending effects only within this range.