Buckling of Imperfect Elliptical Cylindrical Shells under

Results have been obtained for a wide range of cylinder eccentricities (0.5 < B/A < 1.0) which clearly demonstrate that elliptical shells are imperfection sensitive. Elliptical cylinders containing axial imperfection distributions of various wavelengths were subjected to axial compression and their buckling loads compared with those obtained from a corresponding set of geometrically "near-perfect" elliptical cylinders. The shells were sufficiently thin to employ the circular cylinder approximation based on the curvature at the ends of the minor axis to calculate buckling loads. For the case of the perfect elliptical cylinders, theory and experiment were in close agreement. In addition, significant load reductions were found for the imperfect shells for small values of the imperfection amplitude, consistent with predictions based on an equivalent axisymiiietric imperfect circular cylinder theory. It was also observed that a critical axial imperfection wavelength existed which resulted in a minimum buckling load. Postbuckling behaviour was also investigated to determine the extent to which the maximum compressive loads exceeded the initial buckling value as a function of cylinder eccentricity.