Buckling and Post-Buckling Response of 3D Printed Cylindrical Shell with Circular Cutout Under Axial Compression 2024-26-0418

Despite being ubiquitous elements in aerospace structures, thin cylindrical shells’ catastrophic buckling response under axial compression has still remained an enigma. The recent advancements in theoretical and numerical studies aided in realising the role of localisation in shell buckling. However, the buckling being instantaneous made it unfeasible for the experimental observations to corroborate the numerical results. This necessitates high-fidelity shell buckling experiments using full-filed measurement techniques. Cut-outs are deliberate and inevitable geometrical imperfections in actual structures that could dictate the buckling response. Additive manufacturing makes it feasible to fabricate shells with tailored imperfections and study various conceivable designs. 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 certain 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 sequence of propagation of the dimples in the azimuthal direction is also captured. The acquired mode shapes and the strain fields are used to develop a robust Finite Element framework. This can provide accurate digital twin models to investigate the response of cylindrical shells with certain imperfection signatures along with circular cutouts.