Effects of the ballast water state on the dynamic response of cabin structure subjected to underwater explosion

This paper investigates the dynamic response of cabin structure under different ballast states in different underwater explosion (UNDEX) scenarios, aiming to provide references for enhancing the damage capability of underwater weapons and the protective design of ship structures. A 1: 3 scale model of the midship cabin of a certain type of frigate was used as the research object. Far-field and close-in UNDEX experiments were conducted under different ballast states of the cabin structure. A finite element model of the close-in UNDEX was established and its validity was verified, and the evolution of the internal flow field loads and the structural damage process were obtained. The results show that under far-field explosion loads, the cabin is in the elastic response stage, and the peak strain, spectral displacement, and spectral velocity are the largest when it is in full load. Under close-in UNDEX loads, the ballast state first affects the response form of the cabin's outer plate, and then determines the transmission and evolution of the loads in the internal flow field. When the cabin is in full load, the inner plate is subjected to transmitted shock wave load and compression load, and the damage degree of the cabin is the smallest. When the cabin is in half load, the inner plate is subjected to water impact load and compression load, and the damage degree is moderate. When the cabin is in empty load, the inner plate is mainly subjected to the pushing force of the petal crevasse of the outer plate, and the damage degree is the severest.