Flexural Behavior of Functionally Graded-Graphene Reinforced Composite Plates

A first order shear deformation theory based finite element numerical investigation on flexure behaviour of functionally graded thin, moderately thick and thick composite plates reinforced with graphene platelets (GPLs) is presented in this paper. The maximum deflection plays a major role in the design of composite structures. Therefore, maximum deflection and percentage maximum deflection ratio of reinforced to unreinforced composite plate are investigated for a range of GPL distribution patterns along plan and thickness directions of the composite plate. Modified Halpin-Tsai equation is used to determine the effective Young’s modulus for each layer in thickness direction for different distribution patterns. The rule of mixture is used to calculate effective mass density and Poisson’s ratio for each layer. Initially, the results from this study are verified by comparing with the reported results from the literature. Thereafter, validated methodology is used to conduct case study for a simply supported plate, focusing on the effect of thickness, GPL distribution patterns along plan and thickness directions, percentage weight fraction of GPL on the maximum deflection and percentage maximum deflection ratio of reinforced to unreinforced composite plate. It is found that by adding just 1% weight fraction of GPL, the maximum deflection can be reduced by almost 65% to 90% for all thicknesses and distribution patterns considered

Free vibration of functionally graded-GPL reinforced composite plates with different boundary conditions

A first order shear deformation theory based finite element approach is used in this paper to investigate the free vibration behaviour of functionally graded thin, moderately thick and thick multi-layer composite plates reinforced with graphene nanoplatelets (GPLs). The effect of four different layer-wise variations of GPL distribution along the thickness and all possible plate edge boundary condition combinations on the natural frequencies of the plate are investigated. The effective Young’s modulus for each layer and distribution type is determined using the modified Halpin-Tsai model, and mass density and Poisson’s ratio are calculated based on the rule of mixture. Initially, present results are verified by comparing with available reported results. Thereafter, the method is used to conduct a parametric study, focussing on the effect of length to thickness ratio, different boundary conditions, GPL distribution patterns, percentage weight fraction of GPL, and geometry and size of GPL on the natural frequencies and percentage increase in natural frequencies

A sub-laminate based higher-order model for bending of laminated beams containing multiple delaminations

The paper presents a new sub-laminate based higher-order laminated model (HOLM) for modelling the bending response of laminated composite and sandwich beams with and without delaminations of any configuration. The variation of in-plane and transverse displacement fields through the thickness of a sub-laminate is assumed cubic and quadratic, respectively. Such variation involves specifying displacement parameters at the top and bottom surfaces of sub-laminates that provide significant benefit in conveniently modelling perfect and delaminated multilayered beams with any desired level of accuracy. The option exists to therefore trade-off between pre- diction and computational efficiency by adapting a suitable sub-laminate modelling scheme. A C0 continuous beam element with quadratic in-plane variation of displacements is developed for implementation of the pro- posed laminate model. The versatility and accuracy of the model is demonstrated by via a number of numerical examples of composite and sandwich beams, covering a range of variables such as boundary conditions, loading, and delamination configuration. A number of the newly developed results reported in this paper will serve as baseline data for delaminated structures.Yuan Feng, R. Muni Rami Reddy, Abdul Hamid Sheikh, Ching-Tai Ng, Scott T. Smit