Multi-Crack Interaction and Influence on the Spherical Pressure Hull for a Deep-Sea Manned Submersible

This study investigates the interaction and influence of surface cracks on the spherical pressure hull of a deep-sea manned submersible. The finite element model of the spherical hull is established, and a semi-elliptical surface crack is inserted in the welding toe of the spherical hull as the main crack. Considering the combined effect of external uniform pressure and welding residual stress at the weld toe, the stress intensity factor (SIF) is obtained based on the M-integral method. Inserting disturbing cracks at different positions on the spherical hull surface, the interaction and influence between multi-cracks are revealed by numerical calculation. The results show that the existence of the disturbing crack has a great influence on the stress intensity factor of the main crack, and the influence is different with the different location of disturbing crack. The study of the interaction of multiple cracks under different interference factors and the influence of disturbing cracks on the main crack can provide some reference for future engineering applications.