【作者】 任凤华；

【导师】 党惊知；

【作者基本信息】 中北大学 ， 材料加工工程， 2008， 硕士

【摘要】 铸造凝固过程的计算机模拟仿真是学科发展的前沿领域,是改造传统铸造产业的必由之路。同温度场、流动场的计算分析相比,应力场模拟起步较晚,目前发展还不成熟,因此成为铸造过程宏观模拟的研究热点。铸造凝固过程应力场的数值模拟能够帮助铸造工程师预测和分析铸件裂纹、变形及残余应力,为控制应力应变造成的缺陷、优化铸造工艺、提高铸件尺寸精度及稳定性提供科学的依据。本文总结了铸件凝固过程应力场数值模拟研究的进展,以及数值模拟方法、数值模拟软件的发展状况。简要介绍了铸造过程热应力场的特性,建立了瞬态温度场、热应力场弹塑性三维有限元模型,以及温度场中初始条件、边界条件、潜热处理的数学模型。选取有限元分析软件ANSYS进行热应力场数值模拟研究,考虑了材料性能随温度变化的特性,采用非线性分析,对典型铸件——应力框三维温度场、热应力场进行有限元分析。计算结果表明三维温度场的数值模拟能反映铸件冷却过程温度场的动态变化,同时把相变应力加入到应力计算过程中,得到了同理论分析和参考文献一致的应力场模拟结果,验证了处理方法的可靠性。最后,本文运用该模拟方法对实际生产中的座体铸件进行了应力场模拟分析,模拟结果与实际生产情况相吻合,表明所建立的应力场模拟方法能够胜任实际工程应用。更多还原

【Abstract】 Numerical simulation of casting’s solidification processes is the advanced region in foundry develop, it is also the only way via which to modernize the traditional foundry industry. Compared with temperature field simulation and fluid field computation, the stress/strain field analysis starts up later and presently is yet immature, so becomes the hot spot of macro simulation. Stress field calculation can help foundry engineers predict and analyze flaws such as crack, deformation and residual stresses so as to present scientific reference to eliminate defects caused by stress and strain, optimize foundry technology and increase dimensional precision and stability of castings.In this thesis, the development of numerical simulation of thermal stress field during casting process, the method of numerical calculation and the application trend of simulation software are summarized. The character of thermal-stress field during casting process has been introduced in brief. An elastic-plastic 3D FEA model of the transient temperature field and thermal-stress field is theoretically built. And a mathematical model of the initial condition, boundary condition, and latent heat disposal is built as well.Select the FEM software—ANSYS, carry out the study on numerical simulation of thermal-stress field. Considering to the character that the material’s performance changes along with temperature, nonlinear analysis in the procedure is adopted. An FEA analysis is finished for the stress frame 3D temperature field and thermal-stress field of the typical casting-stress frame. The result indicates that the numerical value simulation of 3D temperature field can basically reflect the dynamic change of the temperature field in the casting cooling process. With considering the phase change stress, the results of thermal-stress field calculation are fairly approach to the theory analysis and the references literature. Treatment methods of eutectoids phase and casting-sand boundary are verified well.At last, for engineering application, a piece of seat casting has been analyzed by using the thermal-stress field simulation methods in this thesis. The calculated results are in agreement with the practical results, which demonstrates that methods are competent for the practical application of engineering.更多还原