Buckling tests of cylindrical composite shells in multiaxial loading

Thin-walled cylindrical composite shells are prone to buckling failure in a variety of load cases. The number of influencing factors and comparably small amount of test data on combined load cases, which regularly occur in application, pose a major design challenge. Two experimental campaigns on the buckling of thin-walled cylindrical composite shells in multiaxial loading are carried out with two nominally identical specimens with a radius-to-thickness ratio of 375. The results of buckling tests with combined axial compression and torsion, compression and bending, as well as all three buckling critical load types are presented. The influence of the loading direction of bending and torsion is shown, and the effects of repeated mounting of the specimens in the test rig as well as the scatter of buckling loads are discussed. Comparison of test results with the established NASA SP-8007 guideline and perfect buckling loads shows major qualitative and quantitative differences in the load interaction curves.