Buckling and post-buckling behavior of tubular structures can essentially be affected by the component geometry such as length, diameter, and wall thickness. In this paper, an experimental and numerical study of aluminum and multilayer carbon fiber reinforced plastic (CFRP) tubes under compressive load is discussed, with the aim to extend the knowledge towards extremely large tubular structures. A pin-ended fixture is designed to examine the influence of different support conditions. Experimental results of aluminum tubes show global failure in which critical forces are validated by the Johnson-Euler buckling theory. It also demonstrates that the critical force of a long tube can be the same as a short tube with different ending conditions. However, the tests of CFRP tubes demonstrate more material failure mechanisms and local buckling failure phenomenon. Buckling and post-buckling behavior of CFRP is further investigated by using finite element analysis. A three-dimensional damage model based on the Hashin's failure initiation criteria and cohesive zone method is developed to analyze tensile and compressive damage on matrix and fiber. The combination of experimental and numerical results aims to identify the scale effect on failure mechanisms, failure location, buckling mode, and compressive response. Results show that the stiffness of shorter tube drops significantly due to in-plane shear damage initiation and development. For longer tubes, the stiffness remains the same until the occurrence of local buckling failure, owing to sudden release of strain energy upon arrival of critical force. The main idea in this work is to predict the buckling model and behavior in extremely large aerospace components. Since it would be impractical to test large structures due to the equipment limitation and high cost, the prediction models used in this study would be beneficial for practical designs and applications.
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