【作者】 张桃；

【导师】 王传洋；

【作者基本信息】 苏州大学 ， 机械制造及其自动化， 2011， 硕士

【摘要】 在焊接过程中由于急剧的非平衡加热及冷却,焊接构件将不可避免地产生不可忽视的焊接残余变形。焊接残余变形是影响结构设计完整性、制造工艺合理性和结构使用可靠性的关键因素。然而焊后变形矫正,既不经济又严重伤害其工作可靠性。因此,科学地、定量地预测焊接变形规律,并在此基础上给予控制,对指导焊接制造工艺具有重要的工程意义。本文的主要工作与研究成果概括为以下几个方面:(1)由于推铲的焊缝比较多,以及焊接时间长,因此焊接顺序对残余应力产生的影响极大,本文以推铲焊接为例,首先制定了两种焊接顺序,并根据中性轴对焊接的影响,分析和制定出第三种焊接顺序。(2)采用有限元分析软件ANSYS对焊接过程产生的应力场和变形进行了模拟研究,建立推铲焊件的有限元模型,利用生死单元法模拟焊接过程。对三种不同的焊接顺序进行有限元模拟,得到不同焊接顺序下的焊接残余应力分布及焊接变形。(3)对推铲按照三种焊接顺序进行焊接,并对焊接冷却后的推铲运用了平尺以及高精度三坐标测量仪对三种焊接顺序焊接后的推铲进行实物测量,分析它们的焊接变形情况。(4)最后本文对三种焊接顺序下的有限元模拟结果与实验测量结果进行了比较和分析,结果显示仿真结果与实验测量结果相吻合。证明了中性轴对焊接顺序选择与优化的重要性,具有一定的应用价值。通过研究和实例验证,本文建立了可行的推铲焊接残余应力的动态模拟分析方法,为复杂焊接结构进行三维焊接残余应力和变形的分析提供了理论和指导。更多还原

【Abstract】 Welding residual stress and deformation occurred inevitably in the welding process because of the rapid non-equilibrium heating and cooling, and it can’t be ignored. Residual deformation is a key factor affects the structural design integrity, manufacturing process and the use of structure reliability. The post-weld correction, both diseconomy and injure severely its operational reliability. It is very important to weld engineering if we can scientific, quantitative prediction of welding deformation and give some control on this basis.The main work and research results of this paper summarized as follows:(1) As there are too many weld seams on the shovel, and cost a long time to weld, so the weld sequence impact the welding residual stress highly. This article take shovel welding as an example, developed two welding sequence first, and then analyzed and developed the third welding sequences according to the affects of neutral axis.(2) Finite element analysis software ANSYS used to establish the 3-D model for shovel, simulate the tress field which generated by the welding, establish finite element welding model for shovel, then simulate the welding process by birth and death element technology. Three different welding sequences were carried on the finite element to simulate, obtained the welding residual stress distribution and the welding deformation.(3) Weld the shovel according to the three different sequences, and then this article has also utilized the straight edge and the high accuracy measuring instrument CMM (Coordinate Measuring Machining) measure the shovel after the actual welding, compared and analyzed their welding deformation.(4) Finally we compared and analyzed the simulation results and the measurement results, and it showed that simulation results coincide with experimental results. It proved the important of neutral axis in the welding sequence optimization, and had certain application value.Verified through research and examples, this paper establishes a viable shovel thermal stress dynamic simulation and analysis, provided a theoretical and guidance for three-dimensional structure for complex welding temperature field, residual stress analysis.更多还原