Structural analysis of sandwich plates with variable stiffness composite skins and functionally graded cores using refined zig-zag theory

This work investigates the static flexural behavior of new hybrid Sandwich Plates (SP) with Functionally Graded (FG) cores and curvilinear fiber-reinforced Variable Stiffness (VS) skins. For simplicity and computational efficiency, the existing refined zig-zag theory formulation for curvilinear fiber-reinforced composites with three-node finite element (RZT3C) is enhanced to incorporate the thickness-wise material variation of the FG core. Benchmark problems of FG-SP under various boundary conditions are solved, with results compared against 3D Ansys and reference solutions. Contrary to costlier methods, the presented model accurately captures the complex flexural mechanics, paving the way for designing advanced structures

Implementation of shear-locking-free triangular refined zigzag element for structural analysis of multilayered plates with curvilinear fibers

Modeling and analysis of composites with curvilinear fiber reinforcement is rather challenging in terms of accuracy and computational cost associated with variable material stiffness. In this study, to reduce the computational cost drastically without sacrificing the numerical accuracy, variable stiffness composite laminate (VSCL) is modelled as a single layer based on the refined zigzag theory (RZT). To this end, a three-node triangle RZT element formulation is adopted and effectively implemented for static analysis of multilayer composites and sandwich plates with curvilinear fiber paths. Moreover, to accurately model the strains in VSCL, the derivatives of the zigzag functions with respect to planar coordinates are considered for each ply within the laminate in the RZT kinematic-strain relations. Enhanced capability of the present model is verified by performing comprehensive numerical investigation on several benchmark cases. The obtained results are compared with those present in the literature and three-dimensional elasticity solutions. Hence, it is demonstrated that the triangular RZT element is a fast, robust, and accurate structural analysis platform that can potentially lend itself to the optimization of curvilinear fiber angles of VSCL