Analytical Models for the Response of the Double-Bottom Structure to Underwater Explosion Based on the Wave Motion Theory

Abstract

The aim of this paper is to apply the elastic wave motion theory and the classical one-dimensional cavitation theory to analyze the response of a typical double-bottom structure subjected to underwater blast. The section-varying bar theory and the general acoustic impedance are introduced to get the simplified analytical models. The double-bottom structure is idealized by the basic unit of three substructures which include the simple panel, the panel with stiffener (T-shaped), and the panel associated with girder (I-shaped). According to the simplified models, the analytical models for the corresponding substructures are set up. By taking the cavitation effect into account, the process of fluid-structure interaction can be thoroughly understood, as well as the stress wave propagation. Good agreement between the analytical solution and the finite element prediction is achieved. On the other hand, the Taylor predictions for the panel associated with girder (I-shaped) including the effects of cavitation are invalid, indicating a potential field for the analytical method. The validated analytical models are used to determine the sensitivity of structure response to dimensionless geometric parameters ( ) , ( ) , and ( ) . Based on the dynamic response of the substructures, we establish the approximate analytical models which are able to predict the response of double-bottom structure to underwater explosion.

Study on the Pressure Characteristics of Shock Wave Propagating across Multilayer Structures during Underwater Explosion

“…e shell structure is fixed around the boundary, and the transmitting condition is enforced around the fluid domain so as to overcome the nonphysical reflection. e parameters related to time hereinafter are normalized by the time decay constant θ when r � 10 in equation (8).…”

“…But the major limitation to this method is that the shock wave should be weak enough to guarantee some assumptions they adopted that rigid body motion is negligible and the variation of the wave propagation time in each medium caused by the medium deformation is negligible. Recently, Chen et al [8] applied one-dimensional cavitation theory and section-varying bar theory to discuss the propagation characteristics of stress waves in simple plates and stiffened plates (T profiles and I profiles). Considering the cavitation effect, the pressure and impulse on the wetted surface are predicted accurately by analytical solution.…”