• CN:11-2187/TH
  • ISSN:0577-6686

›› 2011, Vol. 47 ›› Issue (24): 74-82.

• 论文 • 上一篇    下一篇

钛合金激光直接成形过程中热力耦合场的数值模拟

孔源;刘伟军;王越超;卞宏友;赵宇辉   

  1. 中国科学院沈阳自动化研究所;中国科学院研究生院
  • 发布日期:2011-12-20

Numerical Simulation of Temperature Field and Stress Field of Direct Laser Metal Deposition Shaping Process of Titanium Alloys

KONG Yuan;LIU Weijun;WANG Yuechao;BIAN Hongyou;ZHAO Yuhui   

  1. Shenyang Institute of Automation, Chinese Academy of Science Graduate School, Chinese Academy of Sciences
  • Published:2011-12-20

摘要: 为控制成形过程的热应力,根据有限元法中的生死单元技术,利用ANSYS参数化设计语言编程实现对多道多层激光金属沉积成形过程三维温度场和应力场的数值模拟,并对熔池与粉末、激光与粉末的相互作用进行能量补偿,更加准确地计算成形过程中温度场和应力场的动态变化,得到成形过程中模型温度场、温度梯度、热应力场和残余应力的分布规律。结果表明,成形件不同层上的各节点虽然被激活的时间不一样,但它们具有相似的温度变化规律;试样内的温度梯度主要沿z 轴方向分布,熔池区的温度梯度非常大,但其他方向不明显;瞬态热应力集中在温度梯度变化较大的区域,这与热应力形成的机理是一致的;通过对成形件中各方向的残余应力分析,从温度梯度的角度总结各方向残余应力变化规律,侧面验证残余应力的形成机理。通过相同工艺参数下的试验验证,证明上述分析与实际情况是基本吻合的。

关键词: 残余应力, 激光金属直接成形, 数值模拟, 瞬态温度场, 瞬态应力场

Abstract: In order to control the thermal stress of forming process, based on “element birth and death” technology of finite element method, a numerical simulation of three-dimensional temperature field and stress field during multi-track and multi-layer laser metal deposition shaping(LMDS) process is developed with ANSYS parametric design language (APDL). The dynamic variances of temperature field and stress field of forming process are calculated with the energy compensation of interaction between molten pool- powder and laser-powder. The temperature field, temperature gradient, thermal stress field and distribution of residual stress are obtained. The results indicate that although the nodes on different layers are activated at different time, their temperature variations are similar. The temperature gradients of samples are larger near the molten pool area and mainly along z-direction. The transient thermal stress has concentrated in large temperature gradient area, which is in accordance with thermal stress forming theory. Through analyzing the residual stress of the as-formed samples in different directions, distribution rule of residual stress is achieved from temperature gradient perspective. And formation mechanism of residual stress is verified with an indirect way. Finally, it’s verified that the analysis results are consistent with actual situation by the experiments with same process parameters.

Key words: Residual stress, Laser metal deposition shaping, Numerical simulation, Transient temperature field, Transient thermal street field

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