An enhancement of the warping shear functions of Refined Zigzag Theory

The paper presents an enhancement in Refined Zigzag Theory (RZT) for the analysis of multilayered composite plates. In standard RZT, the zigzag functions cannot predict the coupling effect of in-plane displacements for anisotropic multilayered plates, such as angle-ply laminates. From a computational point of view, this undesirable effect leads to a singular stiffness matrix. In this work, the local kinematic field of RZT is enhanced with the other two zigzag functions that allow the coupling effect. In order to assess the accuracy of these new zigzag functions for RZT, results obtained from bending of angle-ply laminated plates are compared to the three-dimensional exact elasticity solutions and other plate models used in the open literature. The numerical results highlight that the enhanced zigzag functions extend the range of applicability of RZT to the study of general angle-ply multilayered structures, maintaining the same seven kinematic unknowns of standard RZT.

Transient analysis of smart composite laminate

In the present study, the transient analysis of smart laminated composite plates is presented analytically using inverse hyperbolic zigzag theory. This theory is displacement based with five unknown primary mid-plane variables in conjunction with the zigzag parameters resembling the membrane and the bending components. The inter-laminar continuity conditions of transverse shear stresses at the interfaces of the smart composite plate are artificially enforced. The dynamic version of principle of virtual work is used to derive the basic equations and solved subsequently with the Navier’s solution technique. Newmark’s time integration scheme is adopted to obtain the solutions of the coupled ordinary differential equations in the time frame. The equilibrium equations of elasticity are employed in order to obtain accurate estimation of transverse shear stresses. Numerical problems on diaphragm supported smart composite plate are solved by evaluating the static responses and comparing them with elasticity solutions in the existing literature. Then the transient responses are derived for a number of time-dependent electro-mechanical loads such as triangular, sine, ramp, and staircase variation. Results show excellent accuracy with the elasticity solutions available in the literature. Further, the dynamic controlling capacity of the piezoelectric layer is studied by evaluating the electrical loads that diminish the mechanical vibrations from the system.

Elasticity Solutions for In-Plane Free Vibration of FG-GPLRC Circular Arches with Various End Conditions

In-plane free vibration of functionally graded graphene platelets reinforced nanocomposites (FG-GPLRCs) circular arches is investigated by using the two-dimensional theory of elasticity. The graphene platelets (GPLs) are dispersed along the thickness direction non-uniformly, and the material properties of the nanocomposites are evaluated by the modified Halpin-Tsai multi-scaled model and the rule of mixtures. A state-space method combined with differential quadrature technique is employed to derive the governing equation for in-plane free vibration of FG-GPLRCs circular arch, the semi-analytical solutions are obtained for various end conditions. An exact solution of FG-GPLRCs circular arch with simply-supported ends is also presented as a benchmark to valid the present numerical method. Numerical examples are performed to study the effects of GPL distribution patterns, weight fraction and dimensions, geometric parameters and boundary conditions of the circular arch on the natural frequency in details.

Three-dimensional multi-patch isogeometric analysis of composite laminates with a discontinuous Galerkin approach

In this study, a three-dimensional discontinuous Galerkin isogeometric analysis framework is presented for the analysis of composite laminates. Non-uniform rational B-splines are employed as basis functions for both geometric and computational implementations. From a practical point of view, modeling with multiple non-uniform rational B-spline patches is required in many different applications due to the complexity of computational domains. Then, a special numerical technique is necessary to couple different non-uniform rational B-spline patches to carry out the isogeometric analysis. In this study, therefore, one of the discontinuous Galerkin methods, namely, symmetric interior penalty Galerkin formulation is utilized to deal with multi-patch isogeometric analysis applications. In order to show the applicability of the proposed framework, composite laminates under sinusoidally distributed load with different stacking sequences are studied in the numerical examples. The predicted results are compared with those obtained by the three-dimensional elasticity solutions and various numerical models available in the literature.