Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
6
材料加工的计算机模拟与仿真
Multipass submerged arc welding
Comparison of transverse residual stresses between simulation and X-Ray diffraction
Monte Carlo Simulation of Grain Growth in Metals
• 2-D simulation • 3-D simulation
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
疲劳性能等）与可靠性分析等等
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
3
材料加工的计算机模拟与仿真
焊接数值模拟：其他焊接方法
• 电阻点焊
– 熔核的形成与控制，性能预测与分析
• 扩散焊
13
材料加工的计算机模拟与仿真
Resistance Welding Temperature Distribution (thermal-electrical interactions)
The following quicktime movie shows typical heating and cooling during resistance welding process in a steel sheet. The movie shows only 1/4th of the geometry due to symetry.
11
材料加工的计算机模拟与仿真
Neural Network for Pulsed - Laser Welding Process
• There are four variables that appear to control the weld pool shape are laser power, welding speed, laser pulse power and laser pulse duration. The interaction between these variables were experimentally studied and an artificial neural network was constructed. Typical calculations from the neural netwrok are shown below.
• Effect of welding speed • Effect of laser power • Effect of laser pulse energy • Effect of laser pulse duration
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
Figure: BMW series 5 rear suspension system
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
8
材料加工的计算机模拟与仿真
Hypermesh modeling of the wing of rear axle system
熔池中气体的吸收 各种氧化物氮化物的形成及其作为非均质核心的可能 凝固－熔质元素分布（偏析）凝固组织大小，结晶路径，BTR区间等
• 结构部分
– 热过程－温度分布，预测热影响区大小，冷却时间，Tmax，th，t8/5等 – 力过程－应力应变过程，残余应力和变形，预测裂纹，控制残余应力和变形 – 冶金过程－晶粒长大，相变，氢扩散，接头组织性能预测，冷裂敏感性预测等 – 接头性能与服役行为－不均质、存在缺陷、残余应力－断裂行为（韧性，强度，
• Simulation with flat electrode Simulation with radius of electrode = 156 mm Simulation with radius of electrode = 35 mm Simulation with radius of electrode = 35 mm (but with 0.1 times contact resistance)
2019/11/3
Figure: Solid Hypermesh model of the part
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
9
材料加工的计算机模拟与仿真
Simulation of welding distortion and residual stresses
14
材料加工的计算机模拟与仿真
Thermal - Electrical - Mechanical Interactions of RSW
Three way coupled model allows one to depict the effects of electrode curvature on the weld development.
2
材料加工的计算机模拟与仿真
焊接数值模拟的研究：电弧焊
• 电弧部分
– 流场、温度场、电场 – 研究各种工艺参数（电流、电压、弧柱气氛，电极伸出长度等等）对温度场，电
流密度，压降分布以及熔滴过渡过程的影响规律
• 熔池部分
– 熔池形状 – 流场、温度场，主要研究成分和工艺因素对熔池形状的影响，针对焊缝形状控制 – 冶金过程
1
材料加工的计算机模拟与仿真
焊接数值分析的内容
• 焊接熔池中的流体动力学和热过程 • 热源与金属的相互作用
– 焊接电弧物理，焊接电弧的传热与传质
• 电弧作用于熔池表面的热能和压力分布 • 熔池表面的变形 • 液态金属的蒸发 • 氢及氮氧等在熔池及环境之间的分配
• 焊接冶金和焊接接头组织性能的预测，包括相变过程 • 焊接应力与变形 • 焊接过程中的氢扩散 • 特种焊的数值模拟
4
材料加工的计算机模拟与仿真
焊接数值模拟：其他加热工艺
• 热处理
– 包括焊后热处理等对应力和变形的影响等等
• 热校核
– 焊后产生变形，用局部加热的方法校正，研 究加热部位，加热量等因素的影响
• 热成形
– 确定加热部位，热源强度，加热时间等等； 可以实现变形的精确控制
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
7
材料加工的计算机模拟与仿真
Aluminium welding of BMW suspension parts
At BMW, SYSWELD is used to predict distortions and residual stresses on welded aluminum frame parts. An example is the wing of the rear axis system of a BMW series 5. The wing is made out of three hydroformed, thick-walled aluminum parts which are welded together by 8 welding joints in a certain sequence.
材料加工的计算机模拟与仿真
焊接过程的数值模拟
• 概述
– 焊接过程数值分析的内容 – 焊接过程的特点 – 焊接过程中温度－应力和变形－组织转变
的关系 – 焊接过程数值分析的主要困难
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University
The simulation gives excellent results on distortions and residual stresses, in comparison with a large series of measurements. The predicted distortions have been within the range of the distortions accessed at the production.
5
材料加工的计算机模拟与仿真
Industrial welding processes
spot
welding
Electron beam welding GTA welding MIG welding
Laser welding
Multipass submerged istortions after unclamping, values strongly amplified
2019/11/3
Zhao Haiyan, Department of Mechanical Engineering, Tsinghua University