﻿ 地质调查船月池结构局部强度评估及优化
 舰船科学技术  2018, Vol. 40 Issue (8): 45-49 PDF

1. 中国舰船研究设计中心，上海 201108;
2. 哈尔滨工程大学 船舶工程学院，黑龙江 哈尔滨 150001

Research on strength assessment and optimization of moon pool structure of a geological research ship
FENG Wei1, YU Yang-zhe2, LI Hui2
1. China Ship Development and Design Center, Shanghai 201108, China;
2. Harbin Engineering University, Harbin 150001, China
Abstract: The strength assessment of a moon pool of a geological research ship was carried out based on direct calculation. First, a three-dimensional finite element model was constructed and the moon pool structure was detailed. The wave loads were computed using linear 3D hydrodynamics associated with the design wave approach and working load was also taken into account in each load condition. Then the stress responses of the moon pool structures under different load cases were calculated. Finally, the strength of the moon pool structure was assessed in accordance with the relevant rules and suggestions were given for improving structural members where stresses exceeded the permissible stress criterion. It can be concluded that the wave load computed using the design wave approach is reasonable and direct calculation is an effective technical method for strength assessment of ships with moon pool structure.
Key words: moon pool     strength assessment     optimization
0 引　言

1 波浪载荷计算原理 1.1 波浪载荷和船体运动预报基本理论

 ${\nabla ^{\rm{2}}}\varPhi \left( {X,Y,Z,t} \right){\rm{ = 0}}\;\;({\text{整个流场}})\text{，}$ (1)

 $\varPhi tt + g\varPhi Z{\rm{ = 0}}\;\;({\text{线性自由面条件}})\text{，}$ (2)
 $\varPhi n{\rm{ = }}Un \;\;({\text{物面条件}})\text{，}$ (3)
 $\mathop {\lim }\limits_{z \to \infty } \varPhi Z = 0 \;\;({\text{底部条件}})\text{，}$ (4)
 $\mathop {\lim }\limits_{R \to \infty } \sqrt R (\varPhi R + \frac{1}{c}\Phi t) = 0 \;\;({\text{远方辐射条件}})\text{。}$ (5)

 $([ M] + [ A])\left\{ {\ddot \eta (t)} \right\} + [ B]\left\{ {\dot \eta (t)} \right\} + [ C]\left\{ {\eta (t)} \right\} = \left\{ {f(t)} \right\}\text{，}$ (6)

 ${S_M}\left( \omega \right) = {\left| {{H_M}\left( \omega \right)} \right|^2} \cdot {S_\omega }\left( \omega \right)\text{，}$ (7)

 $f\left( x \right) = \frac{x}{{{\sigma ^2}}}\exp \left[ { - \frac{{{x^2}}}{{2{\sigma ^2}}}} \right]\text{。}$ (8)

 ${\sigma ^2} \!=\! {D_M} \!=\! {m_0} \!=\! \int_0^\infty {{S_M}\left( \omega \right){\rm d}\omega } \!=\! \int_0^\infty {{{\left| {{H_M}\left( \omega \right)} \right|}^2}{S_\omega }\left( \omega \right){\rm d}\omega } \text{。}\\$ (9)

 $R_{{\rm max}} = 2{\rm{.55}}\sqrt {m_0} \text{。}$ (10)
1.2 设计波系统

 $\zeta = \frac{{R_{\max} }}{{A_0}}\text{。}$ (11)

2 全船有限元模型结构化处理 2.1 全船结构有限元模型

 图 1 全船有限元模型示意图 Fig. 1 Finite element model of the target ship

 图 2 带有消波孔月池结构有限元模型示意图 Fig. 2 Finite element model of moon pool structure

 图 3 月池上井架支座有限元模型示意图 Fig. 3 Finite element model of derrick substructure
2.2 有限元模型重量分布调整

2.3 边界条件

3 计算载荷 3.1 计算工况

3.2 计算载荷

1）波浪载荷

 图 4 水动力网格示意图 Fig. 4 Panel model of the target ship

2）工作载荷

 图 5 工作载荷施加示意图 Fig. 5 Working load applied in moon pool structure
4 月池结构强度评估 4.1 许用应力

4.2 应力计算结果

4.3 结构优化及评估结果

 图 6 优化后井架支座示意图 Fig. 6 Optimized finite model of derrick substructure

1）在4级海况下，井架支座，支座下甲板板，甲板横梁，月池壁和隔板均符合屈服强度要求且未超过许用应力的60%，说明增加板厚及优化井架支座结构的效果较好。

2）在7级海况下，井架支座，支座下甲板板，甲板横梁，月池壁和隔板均符合屈服强度要求。

5 结　语

1）本文所采用的基于三维势流理论的设计波方法所预报的带有月池结构的地质调查船的波浪载荷较为合理可信；

2）基于直接计算法对月池结构的强度进行了校核，经优化后的月池结构局部强度符合强度规范要求；

3）规范中并未对类似船型的月池结构强度校核提供具体方法，本文的校核方法可行，可为类似船型结构设计提供参考。

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