Buckling and Post-Buckling Response of 3D Printed Cylindrical Shell with Circular Cutout under Axial Compression

Thin cylindrical shells are ubiquitous structural elements in aerospace structures, and they experience catastrophic buckling under axial compression. The recent advancements in theoretical and numerical studies aided in realising the role of localisation in shell buckling. However, the instantaneous buckling made it unfeasible for the experimental observations to corroborate the numerical results. This necessitates high-fidelity shell buckling experiments using full-filed measurement techniques. Cutouts are deliberate and inevitable geometrical imperfections in actual structures that could dictate the buckling response. Additive manufacturing makes fabricating shells with tailored imperfections and studying various conceivable designs feasible. Consequently, to comprehend the effect of circular cutout on the buckling response, cylindrical shells are 3D printed in thermoplastic polyurethane (TPU) with a circular cutout of a specific size that could significantly shorten the buckling resistance and tested under axial compression. The full-field response during the pre-buckling, buckling and post-buckling is captured using a Multi-Digital Image Correlation (mDIC) setup. The flexibility of TPU allows repeatability of the experiments, and the viscous characteristic of TPU slows down the pace of the buckling phenomenon, allowing the mDIC setup to capture the full-filed buckling and post-buckling even at a lower frame rate. The effect of loading imperfections on the final stable mode shape in the post-buckling regime is also captured. The acquired mode shapes and the strain fields can be used to develop accurate digital twin models to investigate the response of cylindrical shells with specific imperfection signatures and circular cutouts.