22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-4.1.3

OPTIMISATION OF CUT-OUTS IN FIBRE COMPOSITE COMPONENTS USING FINITE ELEMENT METHODS

R. S. Thomson (1) , S. P. Rajbhandari (2), M. L. Scott (2)
(1) Cooperative Research Centre for Advanced Composite Structures Ltd, Victoria, 3207, Australia; (2) Royal Melbourne Institute of Technology, Australia

Keywords: optimization, cut-outs, fibre composites, finite elements

Structural optimisation has been used to reduce stresses associated with cut-outs and produce optimum designs in composite panels. The optimisation utilised the design sensitivity features of MSC.Nastran and reduced stress concentrations by changing cut-out geometries. Reductions in peak failure indices around the hole boundaries of at least 32% were achieved for a variety of bi-axial and shear load cases. It was found that the optimum cut-out shapes in composite laminates could differ significantly from those in an isotropic panel, especially under shear dominated loading. The methodology developed for cut-outs in plates was applied to the optimisation of a wing rib manufactured from laminated composite materials. The shapes of both the stringer cutouts and access holes were optimised in order to minimise their influence. It was demonstrated that shape optimisation was able to significantly reduce the peak failure indices in the rib, implying that fewer plies would be needed to meet strength requirements.

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