Buckling Load Prediction of Oblate Ellipsoidal Shells Using Force–Stiffness Technique

Abstract

Abstract. Nondestructive evaluation techniques are increasingly applied to estimate the buckling load of shell structures without inducing failure. This study employs the force–stiffness (F–s) method to evaluate the buckling load of oblate ellipsoidal shells subjected to external pressure. Experiments are conducted on five steel shells with comparable R/t ratios, recording pressure, strains, and crown deflections up to failure. Using deflection data up to 80% of the buckling load, the F–s technique predicts buckling with ∼90% accuracy, while incorporating crown strain data improves accuracy to ∼95%. All shells fail within a pressure range of 2.7–3.4 MPa. The method is further validated on 3D-printed aluminum shells, showing promising consistency, though additional testing is required to refine accuracy. Finally, the F–s approach is demonstrated for real-time prediction of a large-scale shell, nearly three times larger than the experimental models, highlighting its scalability and potential for structural applications.