中文摘要：

薄壁镁合金件裂纹缺陷制约着其应用，其成因受多方面因素影响。通过虚拟仿真技术，考察了某薄壁镁合金件压铸充型凝固过程的温度场，凝固过程中产生的热应力，及其对裂纹成因的影响。通过数值分析得出AZ91D铸件裂纹的产生与铸件孔洞类缺陷及凝固收缩不一致产生的应力有关，分析结果与实验一致。以数值分析结果为依据，提出了改进方案。

英文摘要：

The crack defects of thin-walled magnesium components can restrain the development of magnesium alloys＇ application, which are influenced by many factors. By virtue of simulation, the component＇s temperature distributions were shown and discussed, The thermal stress distributions in solidification process were obtained, and the influence facts of crack were investigated. The observation v/a numerical simulation illustrates that the crack behaviour of die cast AZ91D is influenced by porosity defects and inconsistent solidification tensile stresses. The resuits of simulation are in good agreement of the product from the experimentation. According to the results, some suggestions are given to improve the qualities of the components.