A new experimental configuration is designed for large scale Y shape stiffened panels under lateral impact load, which can avoid second impact during test and could be conducted in laboratory condition. The specimens consist of three Y shape stiffeners with one span in the longitudinal direction. The permanent deflections of the steel sandwich were measured by 3D-scan technology. High speed camera is introduced to obtain the velocity history of pendulum bar. Acceleration sensor is set on the indenter to record its acceleration history, which is transferred as the impact force according to Newton second law. The impact force - penetration relationships based on experimental result are compared to existing analytical method.


The collisions between ships would cause the damage of ship structures, and then result in loss of human lives and severe environmental pollutions. There exist two type analysis methods for the ship collision: external and internal mechanics. The external mechanics deals with the global motion of the ship under the action of the collision force and the hydrodynamic pressure exerted on the wetted surface (Petersen, 1992). On the other hand, the internal mechanics concentrates purely on the structural response, evaluating the structural crashworthiness of the ship during accidents (Reckling, 1983).

The response of a ship structure struck by another vessel is usually nonlinear, which depends on the structural arrangement of the ship side and the location of the strike relative to the transverse web frames and bulkheads and on the strength of a striking bow compared with the strength of the struck side. Many parameters associated with the ship collision problem influence the results, including different ship types, drafts, striking bow angles and rakes are considered. (Jones, 1983)

The concept of Y shape stiffener was introduced by Ludolphy (2001), which was used in double hull structure by Damen Schelde Naval Shipbuilding as shown in Fig.1 (a). Practical application of Y shape stiffener in side structure is shown in Fig.1 (b). Using numerical analysis, Klanac et al. (2005) compared the crashworthiness for ten different steel sandwich structures. Naar et al. (2002) and Hu et al. (2005) conducted a series of nonlinear numerical simulations for Y shape structure under lateral impact. These studies found that the double Y type structure can effectively improve the impact resistance ability. It was found that the Y shape structures offered around 40 % higher capacity to absorb collision energy relative to conventional double side. In structural design of ship and offshore structures, it is of high importance to predict the damage caused by collision or grounding.

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