Validation of FE models for buckling analysis of woven GFRP shells

This paper gives the details of a numerical finite element validation study for laminated GFRP cylinders subjected to concentric and eccentric compression. The laminates are of type 'Rovimat 1200' consisting of woven glass fibre roving, with a chopped mat on one side, within a polyester resin matrix. Two and three-ply cylinders with various orthogonal orientations are considered, for which the nominal radius-to-thickness ratio is about 108 and 72, respectively. The numerical results are compared to findings from a previous experimental investigation in which detailed measurements were obtained. Following a brief description of the experimental work, details of the development of suitable finite element models are presented and associated limitations are highlighted. Careful attention is given to thickness idealisation as well as the introduction of geometric imperfections into the numerical models. Both linear eigenvalue analysis and geometrically nonlinear simulations are undertaken using a general purpose finite element program. The correlation between numerical and experimental results is discussed in terms of buckling strength, axial stiffness, buckling deformations and surface strains. The analysis is shown to give a good representation of the buckling behaviour of GFRP cylinders of the type examined. It is also concluded that whereas the cylinders appear to be less sensitive to the effects of initial geometric imperfections than their isotropic counterparts, including such imperfections in a geometrically nonlinear analysis does improve the comparison between tests and finite element results, and is considered essential for the derivation of numerical 'knockdown' factors. (C) 2000 Elsevier Science Ltd. All rights reserved.