Objective Taking the free-flooding non-pressure hull structures of submarines and the double-bottom structures of surface ships as engineering backgrounds, this study investigates the blast resistance characteristics of a typical orthogonal grid sandwich panel structure under different service conditions.
Method A planar shock-wave boundary loading method based on the coupled Eulerian−Lagrangian (CEL) method is proposed. The deformation and failure modes of grid sandwich panel structures subjected to different intensities of blast loading are investigated under three underwater conditions: water only outside the blast-facing plate, water outside the blast-facing plate and within the interlayer, and a fully water-filled configuration. In addition, the influence of water on the structural dynamic response is analyzed from the perspectives of energy absorption and shock-wave transmission.
Results Under blast loading, the face sheets exhibit bending deformation or edge tearing, whereas the grids undergo compression-bending deformation, local wrinkling, or crushing failure. In terms of energy absorption, the water layer between the face sheets reduces the structural strain energy by 18.9%, while the water behind the rear plate reduces it by 91.9%. Under fully water-filled conditions, the stress distribution within the structure becomes more uniform. Furthermore, the presence of water weakens shock-wave reflection at structural walls, enabling most of the incident energy to be transmitted into the water domain behind the plate.
Conclusion The findings elucidate the differences in impact response, damage extent, and failure modes of grid sandwich panel structures under different water-medium conditions, providing a basis for structural design in relevant engineering applications.
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