基于扩展有限元的大功率船用螺旋桨疲劳裂纹扩展研究

发布时间：2018-07-02 07:17

本文选题：螺旋桨 + 疲劳裂纹扩展　；参考：《华中科技大学》2015年硕士论文

【摘要】：大型海洋平台所使用的螺旋桨重达几十吨,直径达到上十米,体积庞大且桨叶曲面复杂,在其服役过程中承受着巨大的推力以及海水的冲击。在复杂海洋环境下,由于海洋平台定位的需要,导致螺旋桨所承受的载荷表现出复杂的强交变性。另外,海水的电化学腐蚀和穴蚀也将加大螺旋桨破坏失效的可能性。随着我国向深海远海进军,上述这些特点均给大功率螺旋桨的设计与制造提出了新的挑战。本文首先通过文献调研,分析总结了螺旋桨发生疲劳断裂事故的特征,提出基于扩展有限元的疲劳裂纹扩展预测模型。以中船重工461厂提供的3500kW全回转推进器为研究对象,基于计算流体力学基础理论,通过水动力学数值仿真,获得不同运行工况下桨叶上的压力分布。将此压力载荷作为边界条件,通过有限元计算得到桨叶上的应力分布,确定应力最大点,即裂纹萌生位置。最后,通过有限元软件ABAQUS中的扩展有限元模块,实现了不同工况下的大功率螺旋桨疲劳裂纹扩展及寿命预测的仿真研究。以上研究结果表明该螺旋桨在最大设计转速以内工作,无论处于何种交变工况下都不会发生疲劳断裂事故;反之,若转速超过该螺旋桨的最大设计转速,在某些恶劣的交变工况下,疲劳寿命较短、断裂事故发生几率较大。
[Abstract]:The propeller used in the large offshore platform has a weight of several tens tons, a diameter of 10 meters, a large volume and complicated blade surface, which is subjected to huge thrust and sea impact in the course of its service. In the complex marine environment, because of the need of offshore platform positioning, the loads of propeller show complex strong alternation. In addition, electrochemical corrosion and cavitation corrosion of seawater will increase the possibility of propeller failure. With the advance of our country to the deep sea, these characteristics pose a new challenge to the design and manufacture of high power propeller. In this paper, the characteristics of propeller fatigue fracture accidents are analyzed and summarized through literature investigation, and a prediction model of fatigue crack growth based on extended finite element method is proposed. Based on the basic theory of computational fluid dynamics and hydrodynamic numerical simulation, the pressure distribution on the blades under different operating conditions was obtained by taking the 3500kW full rotary propeller provided by Zhongzhou-Shipyard 461 Plant as the research object and based on the basic theory of computational fluid dynamics (CFD). Taking the pressure load as boundary condition, the stress distribution on the blade is calculated by finite element method, and the maximum stress point, that is, the location of crack initiation, is determined. Finally, the fatigue crack propagation and life prediction of high-power propeller under different working conditions are simulated by the expanded finite element module in the finite element software Abaqus. The above results show that fatigue fracture will not occur under the maximum design speed of the propeller, and if the speed exceeds the maximum design speed of the propeller, the fatigue fracture will not occur under any alternating conditions. Under some bad alternating working conditions, the fatigue life is shorter and the probability of fracture accident is higher.
【学位授予单位】：华中科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：P742

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