Buckling analysis of variable angle tow composite plates using differential quadrature method

Variable Angle Tow (VAT) placement allows the designer to tailor the composite structure to enhance the structural response under prescribed loading conditions. VAT technology allows curvilinear place-ment of tows within the plane of a structure and gives freedom for altering pointwise in-plane, coupling and flexural stiffnesses of a plate. This stiffness tailoring improves the buckling performance of VAT plates by allowing re-distribution of loads from the critical regions of the plate. In the present work, the Differential Quadrature Method (DQM) is investigated for performing buckling analysis of VAT panels. The governing differential equations are derived for the in-plane and buckling analysis of symmetric VAT plate structure based on classical laminated plate theory. DQM was applied to solve the buckling problem of simply supported VAT plates subjected to uniform edge compression. To show the accuracy and robustness of DQM, the results obtained using DQM are compared with finite element analysis. In this work, Non-Uniform Rational B-Splines (NURBS) curves are used to model the fibre path and the fibre orientation can be designed by modifying the control points within the domain of the plate. The NURBS representation allows general fibre angle variation of tow resulting in wider design space of VAT panels. Also, the number of design variables for VAT panels are reduced by using NURBS curves and the fibre manufacturing constraints can be handled easily. Genetic Algorithm (GA) has been coupled with DQM to determine the optimal tow path for improving the buckling performance.