【作者】 韩绍华；

【导师】 刘雪松；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2008， 硕士

【摘要】 针对高速列车铝合金车体焊后出现的变形问题,开展了车体焊接应力、变形分析以及焊后矫形技术的研究。通过对车体焊接装配过程和火焰矫形过程的有限元模拟,揭示了车体的变形规律,从而为优化焊接工艺,确定变形控制措施奠定基础。本文首先对小尺寸车体结构模型的焊接进行了有限元数值模拟,并对其计算结果进行了实验验证。结果表明模拟结果与测量结果吻合良好,证明了模型的建立以及求解条件施加的合理性。但是这种车体型材结构不但会使得建模的时间大大增加,还会使整个车体模型的单元数量巨大而使现有计算机硬件水平无力承担。因此,本文提出了两种简化结构,并与小尺寸的实际结构模型进行了静力与焊接情况下的等效分析。结果表明,这两种结构不但能够保证与原结构在刚度、焊接残余应力等方面达到等效,而且能够大大减少单元数量从而提高运算速度。利用简化结构建立了整个车体的模型并对其进行了虚拟装配焊接。在对车体八条主要焊缝焊接后,产生了与实际焊接出现的趋势一致的挠曲变形,即两个侧墙均向车体外凸出,中部凸出最为严重,极大破坏了纵向母线直线度。针对这一现象,本文采用了优化焊接次序和焊后火焰矫形的方法来减小车体焊后挠曲变形,并在火焰矫形的模拟计算中采用自行设计的子程序来实现水枪断续行走的动态过程。结果表明,优化的焊接次序和火焰矫形都可以在一定程度上改善焊后挠曲变形。本文还模拟了实际火焰矫形工作中由于不规范操作而出现的压曲失稳变形,研究了火焰加热位置、角度、加热温度等对其影响规律,以此来指导实践生产,保证既可实现对焊后变形的合理调控,又能避免矫形过程中可能出现的压曲失稳变形。更多还原

【Abstract】 This article is mainly analyzing the welding stress and distortion behavior of the aluminum alloy trains for the purpose of controlling the welding distortion and minishing the amending workload. Through the FEM simulation of welding processing of the whole trains’assembling, find out the distortion rules, consequently optimizing the welding technics.The article first simulates the welding processing of small scale plate and validates the simulation results. The validation shows that the simulation result is preferably tally the test result, the established model, the material performance and fixed boundary condition are all advisable. Considering this kind of model will be highly increase the establishing time because of the complicate configuration and the huge number elements of the model even can’t be compute in the present hardware condition. Thereby, bring up two simple configurations to replace the complicate one, and analyze the equivalence of the three configurations. The result indicates that both the two predigestion configurations are equal to the original, and both largely cut down the element number.Establishing the train model by using the predigestion configurations, and assembling it by welding four main parts. After welding the 8 welds including 2 discontinuity fillet weld, appears the same deflection as actual production: both the side walls protrude to the outside of the train, seriously damage the lineless of the vertical- generatrix. Against this phenomenon, this article adopts optimized welding consequence and flame-correction to amend weld deflection, and programmes the process of water-cooling. The result shows that both the two ways could amend the deflection a certain extent. Then simulates the wave transformation because of the improper manipulation during the flame-correction, certificate the effect of some factors, for instance , calefaction position, angle, temperature and so on. This work not only realizes the amending of distortion by optimized welding consequence and flame-correction, but also insures that the flame-correction won’t bring any new distortion.更多还原