Performance assessment of meta-heuristics for composite layup optimisation

Peer reviewedPostprin

Tabakalı kompozitlerin burkulma karşıtı davranışlarının differential evoluation ve simulated annealing metodları ile optimum tasarımı

xi, 51 sayfa : table, figure29 cm. 1 C

Optimum and Robust Design of Fibre-Reinforced Hybrid Composites with Manufacture Related Uncertainties

In this research, different methods are presented for design and multi-objective optimization of laminated hybrid composites when design variables are not deterministic due to manufacture related uncertainties. Since, flexural properties are more affected by hybridization of fibres, this research has focused on the design and optimization of laminated hybrid composites under flexural load. Robustness and hybrid effect are investigated with optimal and robust designs for carbon and glass fibre reinforced epoxy composites being presented

Postbuckling optimisation of variable angle tow composite plates

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

Framework for the Buckling Optimization of Variable-Angle Tow Composite Plates

Variable-angle tow describes fibers in a composite lamina that have been steered curvilinearly. In doing so, substantially enlarged freedom for stiffness tailoring of composite laminates is enabled. Variable-angle tow composite structures have been shown to have improved buckling and postbuckling load-carrying capability when compared to straight fiber composites. However, their structural analysis and optimal design is more computationally expensive due to the exponential increase in number of variables associated with spatially varying planar fiber orientations in addition to stacking sequence considerations. In this work, an efficient two-level optimization framework using lamination parameters as design variables has been enhanced and generalized to the design of variable-angle tow plates. New explicit stiffness matrices are found in terms of component material invariants and lamination parameters. The convex hull property of B-splines is exploited to ensure pointwise feasibility of lamination parameters. In addition, a set of new explicit closed-form expressions defines the feasible region of two in-plane and two out-of-plane lamination parameters, which are used for the design of orthotropic laminates. Finally, numerical examples of plates under compression loading with different boundary conditions and aspect ratios are investigated. Reliable optimal solutions demonstrate the robustness and computational efficiency of the proposed optimization methodology