Reliable buckling load prediction for Ariane 6 test article: Experimental validation of the vibration correlation technique

Kurzfassung

The recent progress of the vibration correlation technique (VCT) has consolidated its viability as a non-destructive experimental procedure for determining the in situ buckling load of unstiffened and skin-dominated stiffened downscaled cylindrical shells. Building on this foundation, the present paper aims to further validate the technique for full-scale, qualification-relevant applications, assessing its robustness in the context of design-proof testing of launcher structures. The specimen investigated is a full-scale launcher tank barrel, representative of the lower section of the hydrogen tank of Ariane 6 first stage. The barrel, composed of four aluminum panels welded together, was tested for buckling at IMA Dresden under the coordination of MT Aerospace AG (MTA) as part of Ariane 6 structural qualification campaign. The experimental campaign involved the first application of the VCT to full-scale buckling tests with combined axial–bending loads, carried out in two configurations: (1) using three out of four actuators evenly spaced around the circumference, and (2) using two actuators from the same setup. For each configuration, non-contact vibration measurements were taken at various load levels. These measured natural frequency variations, along with linear buckling loads obtained from finite element (FE) models, were used to evaluate the robustness and practical applicability of the VCT. The experimental results confirm VCT as a reliable non-destructive technique for estimating the buckling load of imperfection-sensitive, full-scale cylindrical shells. To complement the experimental investigations, a numerical framework is proposed, employing high-fidelity FE models with stochastic, Fourier-based imperfections and realistic loading via a UAMP subroutine in Abaqus, enabling reliable buckling predictions even in the absence of measured imperfection data.