Abstract

In the present paper, a model of a trimaran cross section is taken as the research object to study the slamming phenomenon. The trimaran is released from a height above the water surface and falls into the water along a slide-way to keep the vertical entry attitude. Then the falling height is altered to study the different extent of slamming impact. From the experiment study, it is found two times slamming can be observed during one water entry test due to the special shape of the trimaran cross section. When the main hull splashes into the water, the first slamming is produced. Then the cross structure enters the water, and the second slamming will occur. Thus, this double-slamming phenomenon is investigated in detail. The relationship between the distribution of the slamming pressures and the velocity is analyzed, which provides the theoretical basis for the load prediction and structural design of the cross bridge of trimarans.

INTRODUCTION

With the continuous development of marine resources and ship and ocean engineering, the requirements for ships are higher and higher, therefore various types of high-performance ships have emerged, trimaran is one of them. It is composed of the middle main hull and two slender hulls on both sides. It is connected by the middle connecting bridge. Due to its good transverse stability, seakeeping, small navigation resistance and strong survivability, trimaran has attracted much attention at home and abroad. Although the design and construction of trimaran are more complex than conventional ships, its superior performance makes its development prospect very broad.

When a trimaran is sailing at high speed in bad sea conditions, the relative motion between the hull and the sea wave will induce severe slamming. At the moment of slamming, the ship will experience a huge impact force, and then high-frequency vibration will appear. This is very unfavorable for the strength of the hull structure. At the same time, the structure of the cross bridge connecting the main hull and the sheet is subjected to the large stress, which is easy to produce stress concentration. The line is flat and open, so the slamming problem is especially true for the cross structure and must be considered in the design of the trimaran.

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