Investigation on the dynamic behavior of the ring-stiffened double-shell structure due to subsea collisions

The ring-stiffened double-shell structure is currently widely utilized in the equipment for ocean engineering, of which the response analysis under subsea impact is important to accomplish the safety and highly difficult Marine missions. However, due to the complex characteristics of the research object including fluid-solid coupling contact, large deformation, short response time, and multiplet structure, the dynamic behavior of the impacted ring-stiffened double-shell structure is hard to analyze accurately by traditional numerical methods. To overcome challenges, a fresh modeling and solving approach for the impacting mechanism of the structure body is put forward by this paper. The method is based on the Arbitrary Lagrange-Euler and Fluid-Structure-Interaction (ALE-FSI) theory. A stiffness matrix of a penalty function and steady outer pressure setting is presented to build the underwater interaction model. Then, the ALE-based description method is proposed to simulate the collision process. The results indicate that the adopted modeling and solving methods for the subsea structural collision have better revealed the dynamic response process of subsea structure to impact. There isn’t any evident damage spreading to the surrounding region, and the structural damage is primarily contained in the collision area. When an underwater impact is applied to the double shell structure, the non-pressure shell provides better protection. The core academic achievement of this work is providing an effective approach for subsea impacting mechanism and nonlinear dynamic response of ring-stiffened double-shell structure which can be used in different scenarios. It can offer universal references to optimize the construction of underwater equipment and determine the level of impact damage to submarines.