船体典型构件焊接工艺仿真及分段装焊变形预测研究

发布时间：2018-10-24 18:51

【摘要】：焊接是船舶建造的主要加工手段,焊接水平的高低在很大程度上决定了船舶的建造质量和效率。传统的船体焊接工艺设计过程中主要依靠大量的焊接试验和焊接工人的经验,不仅设计效率低、成本高,而且对焊接参数与焊接性能之间的影响关系也很难掌握。同时,在船体分段装焊过程中,焊接变形的存在不仅造成了分段结构尺寸精度下降和承载能力降低,而且在工作荷载作用下引起的附加弯矩和应力集中现象也是船舶结构早期失效的主要原因,因此,对焊接变形的预测及控制已成为船舶生产中迫切需要解决的重要课题。针对上述问题,本文提出小构件的热弹塑性法和大分段的固有应变法,以热弹塑性有限元法为基础对船体典型构件的焊接工艺过程进行仿真分析,结合固有应变理论对大型船体分段装焊变形进行仿真预测研究,并通过焊接试验验证仿真结果的可靠性,为实际船体焊接工艺的设计提供理论指导。论文主要研究工作如下:(1)针对传统焊接工艺制定过程需要大量试验以及成本高等问题,提出基于热弹塑性有限元法的船体典型构件焊接工艺数值仿真研究。分析船体典型构件多层多道焊接的温度场、变形和应力场的变化规律,设计与数值模拟相同焊接工艺的焊接试验,分别从焊后变形和残余应力两方面验证仿真结果的可靠性。(2)针对目前焊接工艺参数缺乏有效的优化手段等问题,提出单因素控制法的船体典型构件焊接工艺优化。在对船舶焊接工艺深入分析的基础上,基于热弹塑性有限元法对船体典型构件的焊接工艺过程进行仿真优化计算,得到焊接速度、焊接电流和焊接顺序对焊接温度场、变形和应力场的影响关系,为建立焊接工艺参数数据库奠定了基础。(3)针对大型船体分段装焊工艺仿真及变形预测困难等问题,提出基于固有应变法的大型船体分段整体焊接变形仿真预测研究。通过建立固有应变数据库,实现大尺寸、多焊缝的船体分段整体焊接变形仿真预测。为了获得船体分段的最佳装焊顺序,以整体最小变形量为优化目标,对船体分段装焊顺序进行仿真优化计算,并通过船体分段装焊试验验证了优化结果的可靠性。
[Abstract]:Welding is the main processing method of ship construction. The level of welding determines the quality and efficiency of ship construction to a great extent. Traditional hull welding process design mainly depends on a large number of welding tests and welding workers' experience. It is not only low efficiency and high cost, but also difficult to master the relationship between welding parameters and welding performance. At the same time, the welding deformation not only reduces the dimensional accuracy and the bearing capacity of the segmented structure, but also decreases the bearing capacity of the hull. Moreover, the phenomena of additional bending moment and stress concentration caused by working load are also the main causes of early failure of ship structure. Therefore, the prediction and control of welding deformation has become an urgent problem to be solved in ship production. In order to solve the above problems, the thermoelastic-plastic method and the large segment inherent strain method are proposed in this paper. Based on the thermoelastic-plastic finite element method, the welding process of typical hull members is simulated and analyzed. Based on the inherent strain theory, the simulation and prediction of the deformation of large hull segment assembly welding are carried out, and the reliability of the simulation results is verified by welding test, which provides theoretical guidance for the design of actual hull welding process. The main work of this paper is as follows: (1) aiming at the problems of high cost and large amount of experiments in the traditional welding process, a numerical simulation study on the welding process of typical ship hull members based on thermoelastic-plastic finite element method is proposed. The variation law of temperature field, deformation and stress field of multi-layer and multi-pass welding of typical hull member is analyzed, and the welding test of the same welding process as numerical simulation is designed. The reliability of the simulation results is verified from the two aspects of post-welding deformation and residual stress. (2) aiming at the lack of effective optimization methods for welding process parameters at present, a single-factor control method is proposed to optimize the welding process of typical hull members. Based on the deep analysis of ship welding technology, the welding process of typical hull members is simulated and optimized based on thermoelastic-plastic finite element method, and the welding speed, welding current and welding sequence are obtained. The relationship between deformation and stress field lays a foundation for establishing the database of welding process parameters. (3) aiming at the difficulties of simulation and deformation prediction of large hull assembly and welding process, Based on the inherent strain method, the simulation and prediction research on the welding deformation of large hull segment is presented. Through the establishment of inherent strain database, the simulation prediction of hull segment integral welding deformation of large size and multi weld seam is realized. In order to obtain the optimal assembly and welding sequence of the hull segment, the optimal sequence of the hull segment assembly and welding is calculated with the overall minimum deformation as the optimization objective, and the reliability of the optimized result is verified by the hull segment assembly and welding test.
【学位授予单位】：江苏科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U671.8;TG404

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