毕业设计题目：工字钢焊接顺序对变形影响的研究院(系)别：机电及自动化学院专业：机械电子届别：2011届学号：***********名：**指导老师：周广涛讲师华侨大学教务处2011年6月摘要铝合金簿板结构在焊接是存在焊后残余应力大和焊接变形严重等问题，从而限制其应用范围。
因此减小结构上的焊后残余应力和焊接变形具有重要意义。
本文利用有限元模拟铝合金薄板的焊接变形，对厚度为2mm的铝合金薄板焊后变形结果进行分析。
在焊接过程中，焊接区域经历一个复杂的不均匀快速加热和冷却过程，这必然引起焊缝和热影响区发生不均匀的应力应变变化，这种不均衡的应力应变导致焊后形成残余应力和变形的主要原因。
薄壁构件在焊接过程中的变形表现出了特殊性，由于薄壁构件的弯曲刚度小，因此焊后薄壁构件易出现挠曲变形。
焊接热源的局部加热使得焊缝和周围金属产生不均匀的膨胀和收缩，形成残余应力。
对于对接焊缝，纵向残余应力的分布为焊缝附近一定宽度区域为拉应力、两侧区域为压应力，薄板在压应力作用下会发生压曲失稳，当两侧焊接残余压应力大于焊件失稳临界压应力时就会造成焊件的失稳变形。
焊接过程的数值模拟有助于人们从更深层次上理解焊接过程的物理实质，模拟的结果有利于实现对焊接过程的控制。
利用数值方法计算焊接热过程，还可为合理选择焊接方法和工艺参数以及进一步进行冶金分析和动态应力应变分析奠定基础。
模拟铝合金薄板焊接，采用双椭球热源分布模式，基于Marc软件平台，建立了运动电弧作用下焊接过程的有限元数值分析模型，较好的模拟了铝合金薄板焊接变形和整个温度场的变化，对模拟的动态过程进行分析，为以后焊接变形的准确分析起到了参考作用。
关键词：铝合金薄板，焊接变形，温度场，数值模拟ABSRACTAluminum alloy thin plate welding in the welding residual stress exists in Congress and the weiding deformation of serious problems, limiting its scope of application. Therefore reduce the structural welding residual stress and welding distortion is important. Using the finite element simulation of welding deformation of aluminum alloy sheet of shickness of 2mm aluminum plate after welding deformation analysis of the results.In the welding process,welding through a complex uneven regional rapid heating and cooling process, which inevitable lead to weld and heat affected zone of uneven changes in stress and strain, this imbalance in the stress strain caused the formation of residual stress after welding and deformation of the main reasons.Thin-wall components in the welding process of deformation showed specificity, since the bending stiffness of thin-walled components is small, so after welding thin-walled structures prone to deflection. Welding heat source and the local heating around the weld metal makes the non-uniform expansion and contraction, the formation of residual stress. For butt welds, the longitudinal residual stress distribution of a certain width of the region near the weld tensile stress, compressive stress on both sides of the region, sheet in compressive stress occurs under the buckling instability, when both sides of welding residual stress is greater than Weldment instability when the critical stress will cause instability of deformation of weldments.Numerical simulation of welding process helps people from higher level to understand the physical essence of the welding process, the simulation results are conducive to the control of the welding process.Numerical method used welding thermal process, can also be a reasonable choice for the welding method and process parameters as well as further metallurgical analysis and lay the foundation for the dynamic stress and strain analysis. Simulation of welding aluminum alloy sheet, using double ellipsoid heat source distribution model, based on Marc software platform, set up under the action of the movement arc welding process, finite element analysis model, a better simulation of the aluminum alloy sheet welding deformation and the temperature field , on the analysis of dynamic process simulation for accurate analysis ofthe deformation after welding plays a reference.Keywords: thin aluminum alloy plate, the welding deformation, temperature field, numerical simulation目录第一章绪论 (3)1.1课题背景 (3)1.2焊接变形数值模拟的基础 (3)1.2.1焊接变形数值模拟概述 (3)1.2.2焊接变形数值模拟分析的方法 (4)1.2.3焊接变形数值模拟的意义 (5)1.3有限元方法介绍 (5)1.4焊接温度场数值模拟发展研究现状 (6)1.5焊接变形数值模拟发展研究现状 (7)1.6薄板结构的焊接残余应力及变形研究 (7)1.7控制焊接应力和焊接变形的方法研究 (8)1.8主要研究内容 (8)第二章焊接数值模拟建模 (9)2.1实验材料 (9)2.2焊接数值模拟建模 (9)2.2.1有限元模型的建立 (9)2.2.2有限元网格划分 (10)2.2.3施加材料性能 (10)2.2.4建立焊接路径...． (11)2.2.5初始条件和边界条件 (11)2.2.6焊接热输入边界条件 (12)2.2.7散热边界条件 (13)2.2.8力学边界条件 (13)第三章焊揍残余应力和变形数值模拟分析 (16)3.1铝合金薄板焊接温度场的模拟分析 (16)3.2铝合金薄板焊件残余应力的模拟结果分析 (18)3.3铝合金薄板焊件残余变形模拟结果分析 (20)3.4其他变形计算 (21)3.4.1横向收缩量的计算 (21)3.4.2纵向收缩量的计算 (22)第四章常规焊接残余应力和变形实验分析 (23)4.1焊接工艺的确定 (23)4.2常规焊对残余应力的影响 (23)4.3常规焊对纵向挠曲变形的影响 (24)4.4常规焊对焊缝两侧横向位移的影响..............................．26 第五章结论 (29)致谢参考文献附录第一章绪论1.1课题背景近几年来，随着科学技术的迅速发展，焊接工字钢由于较混凝土结构具有施工周期短、结构简单、经济美观的优点，在工业及民用建筑中的应用越来越广泛。
