Full-field deformation reconstruction for large-scale cryogenic composite tanks with limited strain monitoring data

Online deformation monitoring, while of paramount importance in safety evaluation for aerospace composite tanks, is highly challenging due to the complex strain distributions in the composite tank and the strict restrictions of sensor placement. In this study, full-field deformation of large-scale cryogenic composite tanks were reconstructed under thermo-mechanical coupling conditions. In essence, the inner surface strains in the junction area of the head and cylindrical shell of the tank, defined as the 'H-C portion', was derived theoretically based on outer-surface strain measurement. The inverse finite element method (iFEM) was then applied using the measured and derived strains to reconstruct the full-field deformed shape of the tank. A systematic and efficient parametric discussion was conducted using an orthotropic model equivalent with composite laminated models with different lay-ups. The influences of various factors relevant to the material and geometries of the tank on the accuracy of deformation reconstruction were unveiled. Finally, a numerical experiment was carried out to reconstruct the full-field deformation of a large-scale aerospace composite tank with a specific lay-up, where limited strain data analogous to those sparely measured using distributed optical fiber sensors was used. It was found that the sensor placement strategy markedly affects the accuracy of deformation reconstruction.