Buckling of axially compressed CFRP truncated cones with additional lateral load: experimental and numerical investigation

Abstract

Truncated thin-walled conical shells are often used as transition parts between cylinders of different diameters. Parts of space launcher transport systems are one example for the application of conical shells. Buckling of such thin-walled imperfection sensitive structures is a very important phenomenon to be considered during their design phase. Existing design guidelines, NASA SP-8007 for cylinders and NASA SP-8019 for cones, dated from the late 1960’s are currently used in the aerospace industry and employ conservative lower-bound knock-down factors. These empirically based lower-bound methods do not include important mechanical properties of laminated composite materials, such as the stacking sequence. New design approaches that allow taking full advantage of composite materials and take into account specific manufacturing methods are therefore required. The Single Perturbation Load Approach (SPLA) is an alternative proposal for a deterministic procedure for the design of thin-walled cylinders and cones under axial compression that accounts for geometric imperfections. The study deals with the buckling experiments on axially compressed, unstiffened carbon fiber-reinforced polymer (CFRP) truncated cones with an additional lateral load, performed by DLR for validation of the SPLA applied to this type of structure. Three geometrically identical cones with different layup were designed, manufactured and tested. During testing a digital image correlation system was employed and load-shortening data is extracted. The experimental results are compared with the FEA results.