Research on the progressive sagging damage and plastic hinge line mechanism of basic simplified hull girder subjected to near-field underwater explosion bubble

Near-field underwater explosion bubbles are a major threat to the survivability of ships and may lead to severe and destructive accidents. Therefore, in this study, the damage mechanism of a basic simplified hull girder(SHG) under a near-field underwater explosion load is analysed using the Coupled Eulerian-Lagrangian (CEL) method. First, the calculation accuracy of the established finite element model is verified. Then, the damage development process of SHGs to near-field underwater explosions is investigated from the perspective of progressive sagging damage and plastic hinge lines. In addition, theoretical derivations are carried out based on the constructed plastic hinge line mode. Finally, some laws on the simulation data are discussed in terms of the plastic absorption energy and bending moment. The results show that a stable crease mode will appear in the midship when the SHGs are sagging damage under the near-field underwater explosion bubble load. These creases are necessary conditions for sagging damage, which are mainly W-shaped in this study. The analytical solutions of the W-shape size agree well with the simulation results.

Automated summary

In this study, the damage mechanism of a simplified hull girder (SHG) under near-field underwater explosion is analyzed using the Coupled Eulerian-Lagrangian (CEL) method. The finite element model is verified for accuracy. The progressive sagging damage and plastic hinge lines of SHGs under near-field explosions are investigated, and theoretical derivations based on the plastic hinge line model are carried out. The results show that stable creases, mainly in a W shape, appear in the midship when the SHGs experience sagging damage from the near-field underwater explosion bubble load.