Water impact is a highly nonlinear dynamic problem. It can cause severe damage on floating marine structures especially on the trimaran which has large wet-deck. In order to investigate the slamming load distribution and the relationship between the impact velocity and the slamming load, a small scale trimaran model test campaign of water entry from a series of heights is performed based on the similarity theory, and the peak pressure of the main hull, side hull and wet-deck are obtained. Meanwhile, a numerical study on the experiment process is carried out through the nonlinear finite element software MSC.DYTRAN. The results of simulation analysis are compared with the experiment results, and help to determine the relevant parameters used in numerical simulation. The emphasis in the present paper is to put forward a reasonable and effective prediction method of the trimaran slamming loads.
Slamming is caused by impact between a running vessel and the water. Especially for high-speed trimaran, the response include not only main hull bottom slamming, but also consists of harm to the cross structure between main hull and side hulls. In most cases, it is the large pitch and heave motions that force part of the vessel bottom to emerge out of water and subsequently reentery into the water. The generated load is typically characterized by very short-duration, small load acting surface and high peak pressure. The impact can cause severe local damage to the hull, injury to occupants due to high acceleration. What is more, slamming-induced whipping can have a significant impact on both the ultimate bending moment and the fatigue loading of ship structure. Due to the severity and significance of such phenomena on hull, much research effort has been devoted to this area in the past years.