【作者】 黄浩；

【导师】 刘玉君；

【作者基本信息】 大连理工大学 ， 船舶与海洋结构物设计与制造， 2010， 硕士

【摘要】 提高船舶建造的质量,降低生产成本,缩短施工时间,是船舶行业经济发展到一定阶段的必然要求,而改进造船工艺水平又是实现这个目的的主要手段。船舶建造过程应力的研究是改进造船工艺水平的基础,深入研究船舶建造中的应力问题,从力学角度分析船舶建造过程中各项工艺的科学性和合理性,为发现工艺中的问题和施工工艺的改进提供理论基础和技术支持。氧气切割普遍运用于船舶建造中钢板的边缘成形和修造中的切割开孔,为了保证切割构件的安全可靠,准确的推断切割工艺中的力学行为具有重要的理论和工程意义。本文旨在通过研究氧气切割残余应力场的分布规律并通过实验验证,为改善切割工艺和减小切割残余应力的研究提供理论基础。本文首先采用有限元软件进行了平板直线和圆形氧气切割的数值模拟计算,研究了切割过程中对流系数、双热源模型、移动热源的处理以及“生死”单元的实现等问题,分析了切割温度场以及热循环曲线,并得到了氧气切割的残余应力的大小和分布。其次,为了验证有限元数值模拟结果的可靠性和准确性,确定气体火焰高斯热源和铁-氧反应生热率的热效率,本文采用非接触式红外测温技术及测量残余应力的压痕应变法进行钢板的氧气切割实验研究。对比分析了数值模拟结果和实验所测得的数据,结果表明二者比较符合。最后,本文应用经过前文验证的平板直线切割有限元模型,针对不同切割工艺参数进行了参数敏感性分析,研究了切割模型长度、模型边界约束条件、切割速度等因素对切割工艺的影响,总结了温度场和残余应力场随这几种常见影响因素的变化规律。更多还原

【Abstract】 Improving manufacturing quality, reduce the production costs and decreasing labor productivity are inevitable results and requests of the development of shipbuilding economic. It is an important method for advancing quality to improve shipbuilding processes. Researching deeply of the stress problem and analyzing the scientifically in shipbuilding from the mechanical point are to providing a theoretical basis and technical support for discovering the problem of ship construction process and identifying improvement measures.Oxygen cutting is widely used in the edge forming of the steel plates and cutting holes of shipbuilding processes. To ensure the safety and reliability of cutting elements, it has important theoretical and engineering significance to inference accurately of mechanical behavior during cutting process. This paper aims at providing a theoretical basis for improving the cutting process and reducing the residual stress of cutting by researching the distribution of residual stress field of the oxygen cutting and experimental verification.Firstly, this paper does numerical simulation of the line and circle oxygen cutting process using finite element software, and studies convention coefficient and dual heat source model, mobile heat source treatment in cutting process, "life and death" element and so on, analyzes the temperature field of cutting and the thermal cycle curve. The size and distribution of residual stress in oxygen cutting process are obtained finally.Secondly, in order to validate the reliability and accuracy of the finite element simulation results, and to determine the thermal efficiency of Gauss heat source, this paper does oxygen cutting experiments of steel plates using non-contact infrared temperature measurement and the measurement of the indentation residual strain method. The comparative analysis of the numerical simulation results and the experimental results indicate that they are consistent.Finally, this paper does sensitivity analysis for different parameters of cutting process. Study the impact to cutting process of the length of the cutting model, the model boundary conditions, cutting speed, and so on. The variation laws of temperature field and residual stress field is summarized with several common factors.更多还原