Single and two-layer water-separated plates are typical structural forms of warships. Studying the underwater shock wave propagation in such structures is of great significance to explore the shock resistance of warships. This paper aims to reveal the non-contact underwater explosion shock wave propagation characteristics in the single and two-layer water-separated plate model. The non-dimensional analytical models are built for both water-backed freestanding single plate and elastically supported water-backed plate. For the two-layer water-separated plate, a Eulerian compressible fluid model combined with the Newton second law is established to analyze the fluid-solid coupling response. The shock wave reflection and transmission characteristics and dynamic response of plate are analyzed. The results indicate that the fluid-structure interaction parameter ψ significantly influences the propagation of shock waves through a freestanding plate, where the incident wave can be considered completely penetrating the structure for large ψ (ψ > 20, thin plate) while the peak pressure is weakened but impulse is unchanged for small ψ (thick plate). Unlike the freestanding plate, the transmitted wave behind the plate weakens a lot for an elastically supported water-backed plate, because the elastic support restricts the plate motion and makes it rebound. The response of two-layer water-separated plate is much difference with that of single plate. The stiffness of the inner plate support spring Ks plays a key role during the shock wave propagation. The research results are useful in analyzing shock resistance of typical double shell submarines.
During underwater explosion, a highly compressed explosion gas generates strong discontinuous shock wave in the surrounding water (Cole, 1948). The shock wave is characterized by a high steep shock front followed by the attenuated pressure and subsequent oscillations of gas bubbles. During middle/far field underwater explosion, the main damage to the warships is caused by the shock wave. When the incident wave impinges on structures, it will reflect and the structure will begin to move and deform. This process consists of complicated sequence of physical phenomenon, including structure deformation (Chen et al., 2009; Gupta et al., 2010; Feng et al., 2019; Jiang and Olson, 1995), fluid cavitation (McMeeking et al., 2008; Kennard, 1943; Bleich and Sandler, 1970; Jin et al., 2021) and fluid-solid interactions (Geers, 1978, 1994a, 1994b, 2000).