21st Congress of International Council of the Aeronautical Sciences, Melbourne, Australia, 13-18 September, 1998
Paper ICAS-98-5.9.2

THE EFFECT OF DAMAGE ON THE PERFORMANCE OF POSTBUCKLING FIBRE COMPOSITE SHEAR PANELS

Thomson R. S., Scott M. L.*
Cooperative Research Centre for Advanced Composite Structures Ltd., Australia; *Royal Melbourne Institute of Technology, Australia

Keywords: postbuckling, fibre, composite shear panels, delamination

The postbuckling performance of three-blade-stiffened carbon fibre/epoxy shear panels containing artificial delaminations has been investigated. The working dimensions of the panels were 250 x 250 mm with 25 mm high stiffeners. The skins of the panels were 1 mm thi9k consisting of eight plies of uni-directional carbon fibre/epoxy tape, while the stiffeners were 2 mm thick consisting of 16 plies. Static tests under in-plane shear loading showed that buckling initiated at 28 kN (79 N/mm), delamination growth at 48 kN (136 N/mm) before ultimate failure at approximately 60 kN (170 N/mm). An analysis technique to determine the effect of the delamination was proposed based on the virtual crack closure technique. The strain energy release rate around the circumference of the imbedded delamination was determined from a geometric nonlinear finite element analysis using two-dimensional plate elements. The predicted location and mode of delamination growth was shown to agree well with experimental results. Further work is required to be able to predict the actual failure load due to the mixed mode failure experienced.

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