钢薄板复合热源搅拌摩擦焊温度场及应力变形数值模拟

发布时间：2018-03-04 16:27

本文选题：复合热源　切入点：高熔点材料　出处：《南京理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着焊接技术的不断发展,"绿色焊接"的理念被提出,如何减少焊接过程中的弧光、粉尘、噪音等有害物质,降低对操作人员身体的伤害,成为该理念重要研究内容。搅拌摩擦焊(FSW)正是在这一时期从发明到广泛应用迅速发展起来,搅拌摩擦焊接过程中没有电弧、粉尘颗粒和有毒臭氧及氮化物等传统熔化焊的缺点,且此焊接方法为固相连接,避免了金属熔化再凝固带来的硬质相缺陷。目前FSW主要应用于铝、镁等低熔点合金,而在高熔点金属材料方面的实际工程应用几乎没有。为拓展搅拌摩擦焊在高熔点材料方面的应用,本文针对高熔点材料Q235A钢薄板复合热源搅拌摩擦焊展开数值模拟计算的研究,具体内容如下:(1)针对无针光轴肩搅拌头的搅拌摩擦机理,提出中心到边缘热输入非线性增大的反高斯搅拌摩擦焊热源模型。利用有限元分析软件ANSYS对TIG电弧+搅拌摩擦焊+底部预热复合热源高熔点材料钢薄板对接焊先进行温度场的热分析计算,得出焊接中温度全过程。利用自主设计的热电偶测温系统测量工件上特征点的热循环曲线,并与模拟值曲线进行对比,拟合程度非常高,验证了热源模型与散热条件处理的正确性。(2)利用顺序(间接)耦合方法将热分析结果通过载荷形式施加到结构求解计算中,求解计算高熔点材料钢薄板复合热源焊接过程中的应力变化与残余应力分布,得到焊接过程应力变化的规律。通过热弹塑性法计算出薄板的焊后变形量,利用百分表测量出对接板的相对变形量,对比试验变形测量值基本吻合,验证了结构计算方式与约束载荷的正确。(3)通过单因素变化试验对比与正交模拟试验的方法,分析了不同焊接工艺参数对高熔点材料钢薄板复合热源焊接过程中焊缝温度变化影响规律和程度,研究表明:工艺参数的变化使得焊缝上峰值温度出现整体上升或下降趋势,且各因素对焊接温度的影响程度大小排列为焊接速度TIG电弧焊电流搅拌头转速。
[Abstract]:With the continuous development of welding technology, the concept of "green welding" has been put forward, how to reduce the arc, dust, noise and other harmful substances in the welding process, and reduce the damage to the operator's body. It is in this period that FSW has developed rapidly from its invention to its wide application. In the process of FSW, there is no arc, dust particles, toxic ozone, nitride and other shortcomings of traditional fusion welding. This welding method is solid phase bonding, which avoids the hard phase defect caused by melting and solidification. At present, FSW is mainly used in low melting point alloys such as aluminum, magnesium, etc. In order to expand the application of friction stir welding in high melting point material, the numerical simulation of high melting point material Q235A steel sheet composite heat source friction stir welding is carried out in this paper. The specific contents are as follows: 1) the friction mechanism of the shoulder stir head without a needle, A heat source model of anti-#china_person0# friction stir welding with nonlinear heat input from center to edge is proposed. The heat source of high melting point steel sheet with preheated composite heat source at the bottom of TIG arc friction stir welding is first welded by finite element analysis software ANSYS. Thermal analysis and calculation of the temperature field, The whole process of welding temperature is obtained. The characteristic point thermal cycle curve of workpiece is measured by the self-designed thermocouple temperature measuring system, and compared with the simulated value curve, the fitting degree is very high. The correctness of heat source model and heat dissipation condition treatment is verified. The sequential (indirect) coupling method is used to apply the results of thermal analysis to the structural solution by means of load form. The stress variation and residual stress distribution in the welding process of high melting point steel sheet are calculated, and the variation of stress in welding process is obtained. The deformation of the plate after welding is calculated by thermoelastic-plastic method. The relative deformation of the butt plate is measured by using the percentile, and the measured value of the deformation in the contrast test is basically consistent, which verifies that the calculation method of the structure is correct and the constraint load is correct. The method of comparing the single factor variation test with the orthogonal simulation test is verified. The influence of different welding process parameters on weld temperature variation during welding of high melting point steel sheet with composite heat source is analyzed. The results show that the peak temperature of weld increases or decreases with the change of process parameters. The influence of various factors on welding temperature is arranged as welding speed, TIG arc welding current stirring head speed.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG453.9

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