对船舶与海洋工程结构物进行疲劳评估，首先要通过子模型技术解决复杂应力场中裂纹应力强度因子（SIF）的计算问题。针对子模型技术实现过程繁杂且效率较低的问题，分别提出“逐周分层法”，“转换矩阵法”及“映射划分法”并基于VBA及APDL语言编写插件MPC_arranger_V1.0，FEM_coor_transfer_V1.0及Crack_ mapper_V1.0，解决从Patran整体有限元模型到Ansys子模型时壳体单元间MPC创建低效、不同坐标系间节点位置转换困难及裂纹自由划分的局限性问题。基于DNV及ABS相关规范，以某B型LNG燃料舱的疲劳热点为例，对改进的子模型技术进行验证，结果表明经改进的子模型技术可成功施加合理边界条件并实现SIF的求解，可为子模型技术快速实现复杂载荷下裂纹SIF的准确计算提供参考。
Accurate calculation of the stress intensity factors (SIF) of cracks under complex loads must be done firstly using sub-modeling technique in order to evaluate the fatigue behaviour of navel architecture and ocean engineering structures based on fracture mechanics. In view of the complicated and low efficiency problems in adopting sub-modeling technique, the Circumferentially-layering method, Transition matrix method and Crack mapping method are respectively proposed in order to improve the process of creating sub-models in Ansys based on the overall FEM model in MSC.Patran. Plug-ins MPC_arranger_V1.0, FEM_coor_transfer_V1.0 and Crack_mapper_V1.0 are respectively writen in VBA or APDL to accelerate the MPC creation between shell and solid elements, nodes location conversion between different coordinate systems and crack meshing improvement. Based on the related DNV and ABS rules, taking the fatigue hotspot of a B-type LNG fuel tank as an example, the rationality verification of the above methods was performed. The results showed that the plug-ins can greatly and reasonably improve the efficiency of sub-modeling technique. The methods proposed in this article could provide a reference for rapid realization of sub-modeling technique in accurate calculation of the SIF of cracks under complex loads.
2021,43(3): 6-13 收稿日期：2020-01-03
DOI：10.3404/j.issn.1672-7649.2021.03.002
分类号：U661.4
作者简介：黄小平(1963-)，男，博士，副教授。研究方向为船舶与海洋结构物疲劳与断裂
参考文献：
[1] 闫小顺, 黄小平, 梁园华, 等. 波浪载荷作用下海洋结构焊趾表面裂纹的SIF计算[J]. 上海交通大学学报, 2014, 50(2): 288–293
YAN Xiao-shun, HUANG Xiao-ping, LIANG Yuan-hua, et al. Stress intensity factor calculation for surface crack at weld toe of ocean engineering structures under wave loads[J]. Journal of Shanghai Jiaotong University, 2014, 50(2): 288–293
[2] NEWMAN JR J C, RAJU I S. An empirical stress-intensity factor equation for the surface crack[J]. Engineering Fracture Mechanics, 1981, 15(1–2): 185–192
[3] RHEE H C, HAN S, GIPSON G S. Reliability of solution method and empirical formulas of stress intensity factors for weld toe cracks of tubular joints[C]//Offshore Mechanics and Arctic Engineering. 1991, 3: 441−452.
[4] D. BOWNESS, M. M. K Lee. Prediction of weld toe magnification factors for semi-elliptical cracks in T–butt joints[J]. International Journal of Fatigue, 2000, 22(5)
[5] BS7910. Guide to methods for assessing the acceptability of flaws in metallic structures[M]. British Standards Institution, 2005.
[6] VERITAS D N. Strength analysis of liquefied gas carriers with independent type B prismatic tanks, Classification notes No. 31.12[J]. DNV: Høvik, 2013
[7] SRACIC M W, ELKE W J. Effect of boundary conditions on finite element submodeling[M]//Nonlinear Dynamics, Volume 1. Springer, Cham, 2019: 163−170.
[8] CURRELI C, DI PUCCIO F, MATTEI L. Application of the finite element submodeling technique in a single point contact and wear problem[J]. International Journal for Numerical Methods in Engineering, 2018, 116(10–11): 708–722
[9] STRANG G, FIX G J. An analysis of the finite element method[M]. Englewood Cliffs, NJ: Prentice-hall, 1973.
[10] SUN C T, MAO K M. A global-local finite element method suitable for parallel computations[J]. Computers & Structures, 1988, 29(2): 309–315
[11] CORMIER N G, SMALLWOOD B S, SINCLAIR G B, et al. Aggressive submodelling of stress concentrations[J]. International Journal for Numerical Methods in Engineering, 1999, 46(6): 889–909
[12] SUN Y, ZHAI J, ZHANG Q, et al. Research of large scale mechanical structure crack growth method based on finite element parametric submodel[J]. Engineering Failure Analysis, 2019, 102: 226–236
[13] SAINT-VENANT B. Mémoire sur la torsion des prismes[J]. Mémoires des Savants étrangers, 1855, 14: 233–560
[14] MISES R V. On saint Venant's principle[J]. Bulletin of The American Mathematical Society, 1945, 51(8): 555–562
[15] 博嘉科技. 有限元分析软件—Ansys融会与贯通[M]. 北京: 中国水利水电出版社, 2002.
[16] 夏伟, 胡成, 瞿尔仁. Ansys子模型分析技术在处理应力集中时的应用[J]. 工程与建设, 2006(02): 92–94
[17] SHAHANI A R, HABIBI S E. Stress intensity factors in a hollow cylinder containing a circumferential semi-elliptical crack subjected to combined loading[J]. International Journal of Fatigue, 2007, 29(1): 128–140
[18] MARENIĆ E, SKOZRIT I, TONKOVIĆ Z. On the calculation of stress intensity factors and J-integrals using the submodeling technique[J]. Journal of Pressure Vessel Technology, 2010, 132(4): 041203
[19] PERIĆ M, TONKOVIĆ Z, MAKSIMOVIĆ K S, et al. Numerical analysis of residual stresses in a T-joint fillet weld using a submodeling technique[J]. FME Transactions, 2019, 47(1): 183–189
[20] Guide for building and classing liquefied gas carriers with independent tanks[Z]. ABS, 2017.
[21] 季林帅. 深潜耐压圆柱壳极限承载力研究[D]. 镇江: 江苏科技大学, 2015.
[22] 梁园华, 杨清峡, 闫小顺, 等. 老龄半潜式钻井平台节点疲劳裂纹扩展寿命预报[J]. 海洋工程, 2015, 33(6): 20–25
LIANG Yuan-hua, YANG Qing-xia, YAN Xiao-shun, et al. Fatigue crack growth life prediction for a welded detail on an ageing semi-submersible platform[J]. The Ocean Engineering, 2015, 33(6): 20–25
[23] 方敏. 环肋椭圆柱壳振动特性研究[D]. 武汉: 华中科技大学, 2018.
[24] 薛鸿祥, 唐文勇, 曲雪, 等. 4500米级载人深潜器耐压球壳疲劳可靠性分析[J]. 船舶工程, 2013, 35(6): 112–115
XUE Hong-xiang, TANG Wen-yong, QU Xue, et al. Fatigue and reliability analysis of spherical shell for 4500m manned submersible[J]. Ship Engineering, 2013, 35(6): 112–115
[25] 祝慧钞. 潜艇耐压球柱组合壳体极限强度可靠性分析[D]. 哈尔滨: 哈尔滨工程大学, 2016.
ZHU Hui-chao. Reliability analysis of ultimate strength of submarine sphere-cylinder combined pressure shell[D]. Harbin: Harbin Engineering University, 2016.
[26] 姜筠. 晃荡载荷下MOSS型LNG船支撑系统强度分析[D]. 大连: 大连理工大学, 2014.
[27] 孔小兵, 黄小平, 罗盼. 集装箱船纵骨端部焊趾处表面裂纹应力强度因子计算[J]. 中国造船, 2016, 57(2): 67–77
KONG Xiao-bing, HUANG Xiao-ping, LUO Pan. Calculation of stress intensity factors of surface cracks at weld toe of longitudinal stiffener joints in a container ship[J]. Shipbuilding of China, 2016, 57(2): 67–77
[28] 陈景杰, 黄一, 刘刚. 基于奇异元计算分析裂纹尖端应力强度因子[J]. 中国造船, 2010, 51(3): 56–64
[29] 刘帆, 黄小平. 集装箱船典型疲劳评估节点应力强度因子计算[J]. 中国造船, 2015, 56(1): 27–40
LIU Fan, HUANG Xiao-ping. Calculation of stress intensity factor in typical fatigue assessment for container ships[J]. Shipbuilding of China, 2015, 56(1): 27–40
