Postbuckling optimisation of variable angle tow composite plates

Abstract

The potential for enhanced postbuckling performance of flat plates using variable angle tow (VAT), in comparison with conventional laminated composites, has been shown previously. This paper presents an optimization strategy for the design of postbuckling behaviour of VAT composite laminates under axial compression. The postbuckling performance of composite laminated plates for a given compression loading is assessed by studying both the maximum transverse displacement and the end-shortening strain. For the postbuckling analysis of VAT composite plates, an efficient tool based on the variational principle and the Rayleigh-Ritz method is developed. In the optimization study, a mathematical definition based on Lagrangian polynomials, which requires few design parameters, is used to define a general fibre angle distribution of the VAT plate. A generic algorithm is subsequently used to determine the optimal VAT configuration for maximum postbuckling performance. The optimization of square VAT laminates under compression loading for different in-plane boundary conditions is studied and compared with straight fibre designs

Higher-order theories for the free vibrations of doubly-curved laminated panels with curvilinear reinforcing fibers by means of a local version of the GDQ method

“…Variable Angle Tow (VAT) technology allows effectively the placement of fibers along curvilinear paths with the aim of improving buckling and dynamic performances of plates and shells. Many papers have extensively demonstrated that significant enhancements can be achieved utilizing VAT concepts in terms of buckling loads which can be carried out by a variable-stiffness structure [164][165][166][167][168][169][170]. It should be noticed that the Differential Quadrature Method (DQM) was applied by Raju et al [168,169] to solve the differential equations, which govern the buckling problem of VAT plates.…”

Optimization of Tow-Steered Composite Wing Laminates for Aeroelastic Tailoring

“…Alternatively, VAT laminates can be described using mathematical functions (e.g. Bsplines, Lobatto polynomials, Lagrange polynomials) defining either the tow paths or the variations in the fiber angle direction [35]. Different optimization methods have been investigated for VAT laminates.…”

Size-dependent behavior of laminates with curvilinear fibers made by automated fiber placement

“…The control of the fiber path orientation gives freedom to tailor the composite properties in directions within the laminate that are more favorable to carry loads. As a result, superior structural performance of a variable stiffness design over a constant stiffness design can be obtained for a range of structural properties, such as buckling resistance [1][2][3][4], post-buckling [5][6][7], fundamental frequency [8][9][10], and simultaneous maximization of buckling load and in-plane stiffness [11,12]. In practice, the method used by AFP to manufacture a laminate with curvilinear fibers generally leads to the generation of defects in the form of gaps and overlaps.…”