Vibration correlation technique: Methodology applied to buckling of large-scale sandwich cylindrical shell

Abstract

This paper assesses the Vibration Correlation Technique's (VCT) applicability within the context of sandwich cylindrical shells through detailed numerical investigation. The study utilizes a sandwich shell from NASA's Shell Buckling Knockdown Factor project. Finite element models are implemented, incorporating initial mid-surface and thickness imperfections to replicate NASA's buckling test campaign. The numerical results are compared to the experimental data, validating the nonlinear solution with an approximate deviation of 1%. Subsequently, the VCT experimental campaign is numerically conducted through free vibration analyses at different load levels, enabling a comprehensive evaluation of VCT's applicability. The results verified the effectiveness of the VCT, demonstrating a deviation of less than 10% when estimating the buckling load for load levels below 65% of the nonlinear buckling load. Overall, the findings confirm the non-destructive nature of the VCT when employed on such structures, supporting future practical applications.