﻿ 砰击载荷作用下船体局部结构优化设计
 舰船科学技术  2019, Vol. 41 Issue (2): 31-35 PDF

Optimization design on ship local structure under slamming load
SI Hai-long, JIANG Cai-xia, ZHAO Nan
China Ship Scientific Research Center, Wuxi 214082, China
Abstract: In order to do research on ship response induced by slamming load, this paper calculated the slamming coefficient and relative velocity between ship and wave when slamming occur with the software FLUENT and SESAM. " Two-step” method was used to calculate slamming pressure of bow bottom and bow flare. Take into account the distribution of slamming pressure, this paper calculated the ship structure response induced by slamming pressure. This paper revealed that the more close to bow, the higher velocity between ship and wave when slamming occur. Velocity will increase first and then decrease when ship entry water. Optimization design about local bow structure was carried out based on the calculated results.
Key words: slamming loads     structure response     optimization design
0 引　言

1 砰击载荷

 $p = k{v^2}{\text{。}}$ (1)

1.1 砰击系数的确定

 图 1 船首入水模型 Fig. 1 Water entry model of bow

 图 2 P1砰击压力时历曲线 Fig. 2 Slamming pressure

1.2 船体与波浪相对速度

 图 3 SESAM三维计算模型（湿表面） Fig. 3 Wetted surface

 \left\{ {\begin{aligned} & {{Z_R} = d}\text{，} \\ & {{{\dot Z}_R}\text{≤} - {{\dot Z}_{R * }}} \text{。} \end{aligned}} \right. (2)

1.3 砰击压力时历曲线

 $P\left( t \right) = {P_0}\left( t \right){V^2}/V_0^2\text{。}$ (3)

 图 4 砰击压力时历曲线 Fig. 4 Slamming pressure
2 船体结构响应 2.1 砰击压力加载区

 图 5 砰击压力加载区及区域划分 Fig. 5 Domain of slamming pressure

 图 6 船首有限元模型 Fig. 6 Finite element model of bow

3）砰击压力加载方法

4）约束条件

2.2 船体结构响应
 图 7 外板应力云图 Fig. 7 Stress distribution of ship hull plate

 图 8 03甲板以下纵舱壁应力云图 Fig. 8 Stress distribution of longitudinal bulk head under 03 deck

3 船体结构优化设计

 图 9 有限元模型（包含2个肋位） Fig. 9 Finite element model

 图 10 有限元模型（包含5个肋位） Fig. 10 Finite element model

 图 11 有限元模型（包含8个肋位） Fig. 11 Finite element model

4 结　语

1）砰击瞬时，各点的相对入水速度有较大的差异。在船体纵向方向，越靠近船首的位置，相对入水速度越大；在垂向方向，入水速度呈现先增大后减小的趋势；

2）对于原始结构，在177#肋位船体剖面出现突变，因为应力集中，03甲板以下纵舱壁的结构响应较大，达到了580 MPa；

3）对船首局部结构进行优化设计，随着平滑过渡段的延长，外板、01甲板、01甲板纵舱壁、01甲板纵桁、02甲板、02甲板纵舱壁、02甲板纵桁变化并不太明显，平滑过渡段的长度对这些结构的影响并不太大；但对03甲板、03甲板纵舱壁及03甲板纵桁的影响较大，随着平滑过渡段的延长，在方案2和方案3中，这些区域的结构最大应力明显降低。对于结构设计，本文建议采用第3种方案。

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