﻿ 碰撞凹陷对导管架屈曲及疲劳强度的影响
 舰船科学技术  2023, Vol. 45 Issue (19): 25-30    DOI: 10.3404/j.issn.1672-7649.2023.19.004 PDF

The influence of collision depression on buckling characteristics and fatigue strength of jacket
CHEN Bang, SUN Li-qiang, WU Huo-gui, SUN Xiao-fei, MA Jun
Mingyang Smart Energy Group Limited, Zhongshan 528400, China
Abstract: Basing on the jacket leg which has been collision depression under the influence of a typhoon in offshore wind part.Bulid the model of jacket leg,according to worker's field measurment which measured the length,the width and the depth of the jacket leg collision depression, aslo, considering the actual cosllision depression picture. based on the Newton-Simpson method, the impact of the collision depression on the buckling bearing capacity and fatigue strength of the circular tube was studied by using Ansys software.The results show that the critical buckling bearing capacity of the circular tube decreases by 45.87% after considering the collision depression. Under the critical buckling load, the displacement of the complete circular tube increases outward along the radial direction of the circular tube, but the local area of the displacement of the depressed circular tube is inward along the radial direction of the circular tube. After the collision depression, the fatigue damage value of the depression circular tube increases as a whole, comparing with complete circular tube, and also,the maximum fatigue damage area is transferred to the depression area in the middle of the dent.
Key words: jacket leg     collision depression     nonlinear buckling     fatigue damage     depression edge
0 引　言

1 有限元模型 1.1 结构几何模型

 图 1 有限元结构几何模型 Fig. 1 Structure model

 图 2 DH36钢应力-应变曲线图 Fig. 2 The stress-strain curve of DH36
1.2 网格划分及边界条件

 图 3 模型网格划分 Fig. 3 The mesh of jacket model
2 圆管屈曲分析 2.1 屈曲分析理论和流程

 ${F_a} = \frac{{\left[ {1 - \dfrac{{{{\left( {{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r}} \right)}^2}}}{{2C_c^2}}} \right]{F_y}}}{{{5 \mathord{\left/ {\vphantom {5 {3 + \dfrac{{3\left( {{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r}} \right)}}{{8{C_c}}} - \dfrac{{{{\left( {{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r}} \right)}^3}}}{{8C_c^3}}}}} \right. } {3 + \dfrac{{3\left( {{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r}} \right)}}{{8{C_c}}} - \dfrac{{{{\left( {{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r}} \right)}^3}}}{{8C_c^3}}}}}},{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r} < {C_c} ，$ (1)
 ${F_a} = \frac{{12{{\text{π}} ^2}E}}{{23{{\left( {{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r}} \right)}^2}}},{{Kl} \mathord{\left/ {\vphantom {{Kl} r}} \right. } r} \geqslant {C_c} ，$ (2)
 ${C_c} = {\left[ {\frac{{2{{\text{π}} ^2}E}}{{{F_y}}}} \right]^{{1 \mathord{\left/ {\vphantom {1 2}} \right. } 2}}} 。$ (3)

 图 4 非线性屈曲分析流程图 Fig. 4 The drawing of non-linear buckling analysis
2.2 屈曲分析结果

 图 5 圆管位移云图 Fig. 5 The displacement contour of circular tube

 图 6 圆管载荷-位移曲线图 Fig. 6 The load-displacement curve of circular tube

3 圆管疲劳分析 3.1 疲劳计算理论与方法

 $\log N = \log \overline a - m\log \left( {\Delta \sigma {{\left( {\frac{t}{{{t_{ref}}}}} \right)}^k}} \right) 。$ (4)

3.2 疲劳计算结果

 图 7 圆管疲劳损伤云图 Fig. 7 Fatigue damage contour of circular tube

 图 8 凹陷边界疲劳损伤曲线图 Fig. 8 Fatigue damage curve of depression edge

4 结　语

1）在轴向载荷作用下，碰撞凹陷会导致圆管的屈曲承载能力降低，本文圆管发生碰撞凹陷后，屈曲承载能力降低了45.87%。

2）完整圆管在轴向临界屈曲载荷作用下，圆管径向位移沿圆管径向发生鼓曲；凹陷圆管由于发生偏心效应，导致圆管径向位移局部呈沿圆管径向向内凹陷和向外鼓曲的现象。

3）碰撞凹陷后，凹陷区域圆管应力发生重分布，中间凹痕及凹陷边界起主要承受载荷的作用，疲劳损失值较大。

4）碰撞凹陷后，圆管凹陷边界上的疲劳损伤值显著增加，且最大疲劳损伤区域由顶部A点区域转移至凹陷圆管中间凹痕的C、D点区域。凹陷边界上，疲劳损失值呈现从中间凹痕处（C、D点）向凹陷顶部（A点）及底部（B点）逐渐降低的趋势，并且在凹陷底部B点区域疲劳损伤值局部升高。

 [1] 王黎辉, 李其凡, 张建等. 轴压柱形壳非线性屈曲试验与理论研究[J]. 船舶力学, 2021, 25(5): 645–651. WANG Li-hui, LI Qi-fan, ZHANG Jian et al. Experimental and theoretical study on nonlinear bucklingof axially compressed cylindrical shells[J]. Journal of Ship Mechanics, 2021, 25(5): 645–651. [2] 陈斌斌. 圆环耐压壳屈曲特性及试验研究[D]. 镇江: 江苏科技大学, 2019. [3] 武行, 赵海盛, 李昕等. 非对称局部壁厚减薄海底管道的屈曲分析[J]. 海洋工程, 2021, 39(3): 72–82. WU Hang, ZHAO Haisheng, LI Xin. Buckling analysis of pipes with asymmetric local wall thinning[J]. The Ocean Engineering, 2021, 39(3): 72–82. [4] 刘桢. 考虑碰撞凹陷的钛合金耐压壳屈曲研究[D]. 镇江: 江苏科技大学, 2020. [5] 余建星, 薛陆丰, 余扬等. 动态加载模拟凹坑对管道模型压溃影响[J]. 天津大学学报, 2018, 51(7): 667–674. YU Jianxing, XUE Lufeng, YU Yang et al. Influence of denting under dynamic loading on subsea pipeline buckling[J]. Journal of Tianjin University(Science and Technology), 2018, 51(7): 667–674. [6] BARDI F C, Kyriakides. S. Plastic buckling of circular tubes under axial compression partⅠ: Experiments[J]. International Journal of Mechanical Sciences, 2006, 48(8): 830–841. [7] BARDI F C, KYRIAKIDES S. Plastic buckling of circular tubes under axial compression part Ⅱ: Analysis[J]. International Journal of Mechanical Sciences, 2006, 48(8): 842–854. [8] WANG Wei, QIU XinMing. An analytical study for global buckling of circular tubes under axial and oblique compressiong[J]. International Journal of Mechanical Sciences, 2017, 17: 120-129. [9] WANG Yujin, FAN Feng, LIN Shibin. Experimental investigation on the stability of aluminium alloy 6082 circular tubes in axial compression[J]. Thin-Walled Structures, 2015, 89: 54-66. DOI:10.1016/j.tws.2014.11.017 [10] 郭伟国, 史飞飞, 刘风亮. 高强度船体结构钢DH36的动态力学性能研究[C]// 第九届全国冲击动力学学术会议论文集. 2009. GUO Weiguo, SHI Feifei, LIU Fengliang. Investigation on Dynamic Mechanical Performances of DH36 High Strength Shiphull Steel[C]// The 9th National Conference on Impact Dynamics. 2009. [11] SHI Gang, JIANG Xue, ZHOU Wenjing, et al. Experimental study on column buckling of 420 MPa high strength steel welded circular tubes[J]. Journal of Constructional Steel Research, 2014, 100: 71-81. DOI:10.1016/j.jcsr.2014.04.028 [12] DNVGL-RP-C203Fatiguedesignofoffshoresteelstructures[S]. DNVGL. 2020. [13] 孔杰灵. 导管架平台管状构件碰撞受损后的剩余强度研究[D]. 武汉: 武汉理工大学, 2019.