【作者】 李振江；

【导师】 韩建民；

【作者基本信息】 北京交通大学 ， 材料加工， 2010， 硕士

【摘要】 焊接是一个涉及到电弧物理、传热、冶金和力学的复杂过程。焊接现象包括焊接时的电磁、传热过程、金属的熔化和凝固、冷却时的相变、焊接应力和变形等。随着计算机计算能力的不断提高和数值计算技术的发展,有限元数值模拟成为研究各种焊接现象的重要手段。本文系统地论述了焊接过程的有限元分析理论,并以非线性有限元分析为平台,以对接接头为对象,采用SYSWELD软件对TCS345不锈钢对接焊的焊接过程进行了模拟仿真。首先根据不锈钢焊接的试验结果,采用FORTRAN语言,对软件热源进行了二次开发,得到针对本文接头形状热源模型,利用二次开发的热源模型对对焊接过程产生的温度场、残余应力场进行了实时动态模拟仿真。然后进行温度场测试和残余应力场测试,证明得到的热源模型是可行的。利用测温系统,采用在焊接工件表面布置热电偶的方式对焊接过程一些点进行了测量。结果表明在所测点位置温度的计算结果和实测结果符合良好,得到焊接接头的温度变化规律,而且验证了模型的实用性。温度场的数值模拟为进一步研究焊接的应力与组织性能等奠定了基础。对6mm不锈钢板焊接后横向、纵向残余应力进行了测量。测量结果表明,测得的横向、纵向残余应力分布规律与数值模拟结果一致,验证了焊接应力的数值模拟结果的正确性。本文通过实验研究和模拟计算相结合,建立了可行的三维焊接温度场和应力的动态模拟分析方法,为复杂焊接结构进行三维焊接温度场和应力分析提供了理论依据和指导,促进了有限元分析技术在焊接力学分析以及工程中的应用。更多还原

【Abstract】 Welding is a complicated physicochemical process which involves in electromagnetism, heat transferring, metal melting and solidifying, Phase-change, Welding stress and deformation and so on. With the Rapid improvement of computer calculating ability and the advances of numerical calculation technique, numerical simulation with finite element analysis has become the most important means for welding distortion predictions.This paper systemically discusses the welding process via the finite element analytical system. We use the heat source model in SYSWELD to simulate the process of the laser welding based on stainless steel TCS345. First, based on the stainless steel weld experimental result, take application of FORTRAN to carry out second time tap when applied for different shape of weld seam is the advanced form when people use SYSWELD. By utilizing the results to simulate the welding process of butt welding. Meanwhile, the calculation results have little difference with test result. We can prove the heat source model is correct.Via the monitoring temperature system, some points in the test model are measured during welding process by means of thermocouples. As a result, the experimental data is in perfect accordance with calculated data. In conclusion, doing by this way can firmly provide a basis for further research of stress and strain fields in the period of welding process. The welding transversally and longitudinally residual stress and distortion were also measured on 6 mm thick plate. The distributive patterns of residual stresses matched extremely well with the results of numerical simulation as well as testify the results of the numerical simulation.As it can been manifested by the research and numerical stimulation, this paper establishes a feasible dynamic simulation method on 3D welding temperature and stress fields, which provides theory evidence and instruction and promotes the application of FEA on welding mechanics analysis and engineering.更多还原